Patent Publication Number: US-2022234397-A1

Title: System and method for tire leak detection

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 16/745,084 filed Jan. 16, 2020 which is a continuation of U.S. application Ser. No. 16/398,596, filed Apr. 30, 2019 and granted as U.S. Pat. No. 10,688,836, which is a continuation of U.S. Nonprovisional application Ser. No. 15/805,015, filed Nov. 6, 2017, and granted as U.S. Pat. No. 10,315,469, which claims the benefit of US Provisional Application numbers 62/383,919, filed Sep. 6, 2016 and 62/384,652, filed Sep. 7, 2016, all of which are incorporated in their entireties by this reference. 
    
    
     FIELD 
     The present disclosure relates generally to managing fluid pressures and to detecting leaks in a pressurized fluid system. 
     BACKGROUND 
     A problem with conventional central tire inflation systems can arise if one or more of the tires has a leak, and air can flow from the other, non-leaking tires, pressurizing the system, and thereby masking the leak. This can occur with both normally-open and normally-closed wheel-end check valves (WECVs). 
     SUMMARY 
     The present disclosure provides a method for detecting a leak in a pressure vessel of a system including a plurality of pressure vessels in fluid communication with a common header. The method comprises: reducing a fluid pressure in the common header to a first predetermined value below an operating pressure of the plurality of pressure vessels; gradually adding fluid to the common header at a first flow rate to increase the fluid pressure in the common header from the first predetermined value; monitoring, after gradually adding the fluid to the common header, the fluid pressure in the common header; and determining, based on the fluid pressure in the common header after gradually adding the fluid to the common header, a leak in at least one pressure vessel of the plurality of pressure vessels. 
     The present disclosure also provides a system for managing pressure in a plurality of tires of a vehicle. The system comprises: a manifold defining a channel and configured to distribute compressed air from a compressed air source; a common header providing fluid communication between the manifold and each of the plurality of tires; a control valve configured to control air flow from the compressed air source to the common header; a pressure sensor configured to monitor a pressure in the common header; and an electronic control unit in functional communication with the control valve and the pressure sensor. The electronic control unit is configured to: reduce a fluid pressure in the common header to a first predetermined value below an operating pressure of the plurality of tires; gradually add air to the common header to increase the fluid pressure in the common header from the first predetermined value; monitor, after gradually adding the fluid to the common header, the fluid pressure in the common header; and determine, based on the fluid pressure in the common header after gradually adding the air to the common header, a leak in at least one of the plurality of tires. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further details, features and advantages of designs of the invention result from the following description of embodiment examples in reference to the associated drawings. 
         FIG. 1  shows a schematic representation of an embodiment of a tire management system. 
         FIG. 2  shows a flowchart diagram illustrating steps in a method for managing pressure in a tire. 
         FIGS. 3A-3D  show schematic diagrams of the tire management system integrated with a manifold of a vehicle. 
         FIG. 4  shows an arrangement of control valves within a manifold of a vehicle. 
         FIGS. 5A and 5B  show illustrations of air flow in a vehicle during tire deflation and inflation, respectively. 
         FIG. 6  shows an example embodiment of a check valve. 
         FIGS. 7A-7D  show the check valve in various configurations depending on the operation of a control valve. 
         FIG. 8  shows a mounting mechanism retrofittably installed on a hubcap. 
         FIG. 9  shows a mounting mechanism. 
         FIG. 10  shows the mounting mechanism attached to a vehicle axle assembly with a barbed press-in interface. 
         FIG. 11  shows a rotary union. 
         FIGS. 12A-12B  show a rotary union allowing for misalignment between the axle and the hubcap of a vehicle. 
         FIG. 13  shows a block diagram illustrating communication between the system and a remote entity. 
         FIG. 14  shows a block diagram of a tire pressure control system. 
         FIG. 15  shows the tire pressure control system of  FIG. 14 , with a slow leak in one of the tires. 
         FIG. 16  shows a graph illustrating pressures when checking a tire pressure in a system with inflate and deflate control capabilities. 
         FIG. 17  shows a graph illustrating pressures when checking a tire pressure in a system with only inflate control capability. 
         FIG. 18  shows a flow chart illustrating steps in a method for controlling tire pressure in a system with inflate and deflate control capabilities. 
         FIG. 19  shows a flow chart illustrating steps in a method for controlling tire pressure in a system with only inflate control capability. 
         FIG. 20  shows a flow chart illustrating steps in a method for checking a tire pressure. 
         FIG. 21  shows a flow chart illustrating steps in a method for detecting a leak in a pressure vessel. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, the present invention will be described in detail in view of following embodiments. The following description is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use this invention 
     1. Overview 
     The tire management system (TMS) can include one or more control valves  110  and a check valve  120 , and can optionally include an air source  130  and an air sink  140 . The TMS functions to provide an on-vehicle tire inflation system that automatically fluidly isolates a tire  150  from the inflation system (e.g., air source  130 ) in the event of a system leak, but still allows controlled tire deflation during typical use. The TMS can further automatically fluidly isolate the tire  150  from the remainder of the fluid circuit (e.g., from other tires connected to the same fluid circuit) in the event of tire leak, but still allow controlled tire inflation during typical use. 
     The method of TMS operation includes: determining a pressure parameter value S 200 , determining an operational parameter for a valve based on the pressure parameter value S 210 , and controlling the valve based on the operational parameter S 220 . The method functions to selectively control the TMS system to avoid triggering automatic tire fluid isolation during selective tire deflation and/or inflation. 
     Variants of the tire management system (TMS) and method confer several benefits over conventional tire pressure management systems and methods. First, in some variants, the check valve seals closed at a system leak (e.g. when the vehicle is in a ‘key-off’ state), isolating the system from the tire. These variants can confer the benefit of preventing tire deflation when the vehicle is parked, which further aligns with regulations regarding minimum required inflation amounts of a tire. Second, in some variants, the system deflates a tire to a target tire pressure through dithering of the control valve. These variants can confer the benefit of controllably deflating a tire without activating a check valve seal. Additionally, some variants confer the benefits of both the first and second variant, which are traditionally at odds due to the risk of sealing a check valve during traditional deflation (non-dithered), which could be dangerous to the driver as well as require intervention at the tire to unseal the check valve. Fourth, in some variants, the check valve is bidirectional. This can confer the benefit of isolating the system from the tire in the case of a system leak as well as isolating the tire from the system in the case of a tire leak (e.g. tire blowout). Fifth, in some variants, the check valve is passive and/or the control valve is non-proportional, both of which can confer the benefit of a relatively low cost of manufacture of the system. 
     2. System. 
     As shown in  FIG. 1 , the TMS  100  includes a control valve  110  and a check valve  120 . The TMS  100  can additionally include an air source  130 , an air sink  140 , a tire  150 , a manifold  160 , a pressure sensor  170 , a controller  180 , a vehicle condition database  185 , and/or a mounting mechanism  190 . Additionally or alternatively, the TMS  100  can include any other suitable components. Each TMS can be connected to one or more tires  150  through the same or different manifold in parallel, in series, or a combination thereof. Each vehicle can include one or more TMS′  100 , wherein multiple TMS&#39; can be connected to the same or different tires. Multiple TMSs can optionally share components (e.g., control units), data (e.g., transferred from a first TMS to a second TMS), or any other suitable element. 
     2.1 Air System. 
     The system can further include any or all of an air system, wherein the air system includes the following air system elements: an air source  130 , an air sink  140 , and a tire  150 . However, the air system can include any other suitable component. 
     2.2 Air Source. 
     The air source  130  functions to provide compressed air to a tire in a vehicle (e.g. a truck). Preferably, the compressed air is only provided to a tire when the compressed air in the air source is at a higher pressure than the air in the tire. Alternatively, the compressed air can be provided to the tire at any time. Additionally or alternatively, the air source  130  can function to provide compressed air to other elements in the system or vehicle (e.g. to the braking system, suspension system, etc.). Preferably, the air source  130  is fluidly connected to a tire, wherein the air source  130  transmits compressed air to the tire during tire inflation. Alternatively, the air source  130  can be fluidly connected to a pair of tires, all the tires in a vehicle, or any number or combination of tires. Preferably, the air source  130  is also fluidly connected to a compressor, wherein the air source  130  receives compressed air from the compressor. Additionally or alternatively, the air source  130  can include a compressor and/or be fluidly connected to ambient air or any other air source. Further alternatively, the air source can be fluidly connected or otherwise connected to any other component of the vehicle, an external pump, a conduit inside or outside the vehicle (e.g. hose), or any other suitable component. Preferably, the air source  130  is a reservoir of compressed air (e.g. a compressed air tank). Alternatively, the air source  130  is a reservoir of compressed fluid, a compressor, a pump, or other suitable device. Preferably, there is a single air source  130  in the TMS  100  system. Alternatively, there can be one air source  130  per tire in the vehicle, one air source  130  among multiple vehicles, or any other arrangement of the air source(s)  130 . Preferably, the air source  130  contains compressed air at all times of vehicle operation. Alternatively, the air source  130  can operate between one or more modes. In one variation, the modes are binary, wherein the air source  130  contains compressed air in one mode (e.g. when the vehicle is in a ‘key-on’ state) and contains air at atmospheric pressure in another mode (e.g. when the vehicle is in a ‘key-off’ state). In another variation, there can be any number of operational modes for the air source  130 . 
     2.3 Air Sink. 
     The system can further include an air sink  140 , which functions to remove air from a tire in a vehicle. Preferably, air is only removed from a tire when the air in the tire is at a higher pressure than air in the air sink  140 . Alternatively, air can be transmitted from the tire to the air sink  140  at any time. Additionally or alternatively, the air sink  140  can function to remove air from other elements in the system or vehicle (e.g. from the engine). Preferably, the air sink  140  is fluidly connected to a tire, wherein air flows from the tire to the air sink  140  during tire deflation. Alternatively, the air sink  140  can be fluidly connected to a pair of tires, a set of tires, or any number or combination of tires. Preferably, the air sink  140  is or is fluidly connected to the ambient environment of the vehicle. Alternatively, the air sink  140  can be fluidly connected or otherwise connected to a filter, a reservoir/tank, a conduit inside or outside the vehicle (e.g. hose), another component of the vehicle, or any other suitable component or environment. Preferably, the air sink  140  is a conduit (e.g. hose). Alternatively, the air sink  140  is a valve, or any other suitable outlet. Preferably, there is a single air sink  140  in the TMS  100  system. Alternatively, there can be one air sink  140  per tire in the vehicle, one air sink  140  among multiple vehicles, or any other arrangement of the air sink  140 ( s ). Preferably, the air sink  140  permits air transmission at all times of vehicle operation. Alternatively, the air sink  140  can operate between one or more modes. The modes can be binary, wherein the air is open in one mode (e.g. when the vehicle is in a ‘key-on’ state) and is closed in another mode (e.g. when the vehicle is in a ‘key-off’ state). Alternatively, there can be any number of operational modes for the air source. In one example, the air sink  140  is configured to permit a specified rate of air flow depending on a tire pressure parameter (e.g. pressure value). 
     2.4 Tire. 
     The system can further include a tire  150 , wherein the tire  150  is attached to the vehicle and functions to provide traction between the vehicle and the terrain over which the vehicle travels. Additionally or alternatively, the tire  150  can function to absorb shock transferred to the vehicle from the terrain, support the load of the vehicle, and/or determine the direction of vehicle travel. Preferably, the tire  150  is attached to the vehicle and fluidly connected to both an air source and an air sink. Alternatively, the tire  150  can be fluidly connected to one of an air source and an air sink, or neither an air source nor an air sink. In one variation, the tire  150  is fluidly connected to both an air source and an air sink with a single conduit. In another variation, the tire  150  is fluidly connected to an air source with a conduit and to an air sink with a separate conduit. In one example, the conduit is an axle  168  (e.g. a pressurized axle) in a vehicle. In another example, the conduit is a hose assembly (e.g. a pressurized axle tube). Preferably, the tire  150  has a cylindrical shape formed by an external shell configured to retain air. Alternatively, the tire  150  can have a spherical shape or any other suitable shape. Preferably, the external shell is rubber (e.g. synthetic rubber, natural rubber). Alternatively, the external shell can be a fabric overlaid on a wire mesh, a carbon block compound, or any other material. Preferably, the tire  150  has a pattern of grooves (e.g. tread) arranged on all or part of the external shell which makes contact with the ground. In a cylindrical variation of the tire  150 , a tread pattern, for example, can be fabricated on the outer wall of the tire  150 . Alternatively, a pattern of grooves may be arranged on the entire 150 external shell or on any part of the external shell. In one variation, the system includes four tires  150  per axle  168  of a vehicle. In another variation, the system includes two tires  150  per axle  168  of the vehicle. In other variations, the system includes a single tire  150  or any number of tires  150 , arranged in any way with relation to each other and to the vehicle. 
     Preferably, the tire  150  further comprises a tire valve  151  configured to provide an attachment site with which to fluidly connect the tire  150  to an air source and/or an air sink. Preferably the tire valve is fluidly connected to an air source or an air sink via an intermediary component (e.g. a conduit), wherein the tire valve is attached to one end of the intermediary component (e.g. a threaded tube). Alternatively, the tire valve can be directly attached to an air source and/or an air sink. Preferably, the tire valve is a poppet valve (e.g. Schrader valve). Alternatively, the tire valve can be a check valve, a spool valve, a plug valve, or any other valve. Preferably, the tire valve is configured for two-way air flow, but can alternatively be configured for one-way air flow or any number and arrangement of air flows. Preferably, the tire valve is passive, but can alternatively be actively controlled (e.g. by a control unit). Preferably, each tire  150  has two tire valves but can alternatively have a single tire valve or any number of tire valves. 
     In one variation, the tire  150  and/or TMS further includes a pressure sensor connected to the tire  150 , wherein the pressure sensor is configured to determine a pressure parameter of the tire  150  (e.g. pressure value of air within external shell, pressure rate of flow into/out of tire  150 , etc.). In one example, for instance, the pressure sensor is coupled to the tire valve, wherein the value of the pressure parameter measured by the pressure sensor is used, at least in part, to determine the operational mode of the tire valve (e.g. open, closed, open for a specified direction of flow, etc.). In a second example, the pressure sensor is connected to manifold fluidly connected to the tire interior. This manifold can be the fluid manifold fluidly connecting the tire  150  to the air source  130 , the air sink  140 , and/or to any other suitable endpoint, wherein the tire pressure can be measured by holding the tire valve in an open position, sealing an upstream valve, arranged between the tire and the endpoint, and measuring an interstitial pressure. However, the tire pressure can be otherwise determined. 
     2.5 Manifold. 
     The system can further include a manifold  160 , which functions to direct fluid flow between air system elements. Preferably, the fluid flow is cooperatively directed by one or more valves (e.g. control valves), but can alternatively be directed independently or by any other suitable component. Additionally or alternatively, the manifold  160  functions to contain (e.g. enclose, mechanically protect) one or more system components (e.g. control valves, check valves). Additionally or alternatively, the manifold  160  can function as a substrate for attachment of system components and/or external components. 
     In a first variation, variation, the manifold  160  is a set of one or more fluid connections, wherein the fluid connections are configured to fluidly connect an air source and an air sink to a tire. The fluid connections can be flexible, rigid, or have any suitable property. The fluid connections can be hoses, tubes, lumens (e.g., axle lumens), or be otherwise configured. In one example, one hose connects the tire to an air source while another conduit connects the tire to an air sink. In another example, one hose connects the tire to an air source while a second hose connects the tire to an air sink, wherein the first and second hoses are connected with a channel. In one variation in which the TMS is a central tire inflation system, the manifold extends from a central air source (e.g., air reservoir), through or along the axles, to the wheel ends. However, the air can be otherwise routed to the wheel ends. 
     In a second variation, the manifold  160  is a centralized air routing component that accepts auxiliary fluid connections to route air to the tires. The manifold  160  is preferably made of a thermoplastic (e.g., nylon or polyvinyl toluene with a 30% glass fill), but can alternatively be made of another synthetic or natural polymer, a flexible material (e.g. rubber), metal (e.g., an axle lumen, metal tube, etc.), composite material, or any other suitable material. The manifold  160  is preferably injection molded, but can alternatively be milled out of a single block of material (e.g., metal, plastic), cast out of metal, composed of separate sub-components which are fastened together, or made using any combination of these or other suitable manufacturing techniques. 
     The manifold  160  may define one or more ports  114   a ,  114   b ,  114   c ,  114   d , which function to fluidly connect the air system elements. The ports  114   a ,  114   b ,  114   c ,  114   d  can also function to receive an external fitting and/or attachment (e.g. a threaded quick-release compressed-gas fitting, barbed fitting, hose, pressurized axle tube, etc.) that facilitates fluid connection of the port to the air system element. In one variation, each air system element has its own port. In other variations, a single one of the ports  114   a ,  114   b ,  114   c ,  114   d  may be shared among multiple air system elements. In other variations, a single air system element is connected to multiple ports  114   a ,  114   b ,  114   c ,  114   d . The port preferably defines a straight flow axis, but can alternatively define a curved flow path, a branched flow path (e.g., with at least a third end in addition to the first and second end), or any other suitable path along which air can flow through the port. In variations including a plurality of ports  114   a ,  114   b ,  114   c ,  114   d , the flow axis of each port  114   a ,  114   b ,  114   c ,  114   d  may be parallel to each of the other flow axes of each of the other ports  114   a ,  114   b ,  114   c ,  114   d . In one example, the first and second ports  114   a ,  114   b  are arranged with the respective flow axes sharing a common plane (port plane). However, multiple ports can be arranged offset from each other, at a non-zero angle to each other, or be arranged in any other suitable configuration. 
     The manifold  160  preferably includes a channel  161  (galley) which functions to provide fluid connections between ports, but can be otherwise configured. The channel  161  preferably contains compressed air from the air source that is simultaneously accessible to each of the control valves (e.g., is connected to the control valves in parallel), but can be serially connected to the control valves or otherwise connected. The channel  161  preferably intersects the ports between the respective first and second ends of each port, but can alternatively be connected by a secondary manifold  160  or otherwise connected to one or more ports of the manifold  160 . The channel  161  is preferably fluidly connected to every port of the manifold  160 , but can alternatively be connected to a first subset of ports and fluidly isolated from a second subset of ports. In one variation, the channel  161  connects one port to a second port. The pressure sensor is preferably fluidly connected to the channel  161  and measures the pressure of whichever downstream element is fluidly connected to the channel  161 , but can alternatively be arranged within a port, along a fluid connection, or be otherwise arranged. The channel  161  preferably extends normal the port, but can alternatively extend parallel to or at any other suitable angle to the port. The channel  161  preferably lies in the same plane as the ports, but can alternatively be offset from the port plane (e.g., lie above or below the port plane, extend at an angle to the port plane, etc.). The channel  161  is preferably substantially linear (e.g., define a substantially linear flow axis), but can alternatively be curved (e.g., toward or away from the second end, out from the port plane, etc.) or have any other suitable configuration. However, the channel  161  can be otherwise configured or arranged. The channel  161  is preferably connected to an output of a filter  162 , but can alternatively be connected directly to an air element. 
     In a first embodiment, the manifold  160  is the manifold  160  in the electronically controlled vehicle suspension system in U.S. Provisional Application No. 62/384,652 filed 6-Sep. 2017, which is incorporated in its entirety by this reference. In one example, the manifold  160  includes a first port  114   a  coupled to an air source, a second port  114   b  (e.g., exhaust port) coupled to an air sink, and a third port  114   c  coupled to a tire (e.g. through the tire valve), wherein the three ports  114   a ,  114   b ,  114   c  are fluidly connected through a single channel. The manifold  160  can optionally include a fourth port  114   d  fluidly connected to a suspension system  163  (e.g., air spring). However, any other suitable manifold  160  can be used. 
     2.6 Control Valve. 
     The control valves  110  may function to selectively bring a tire  150  into fluid connection with one or more air system elements (e.g.  FIGS. 3A-3D ). In some embodiments, the control valves  110  each include a two-way valve. Alternatively, one or more of the control valves  110  may include a three-way valve, or can have any number of inlets and outlets in any arrangement. The control valves  110  may be operable between an open position, permitting fluid connection between a tire  150  and an air system element, and a closed position, wherein the control valve  110  prevents fluid connection between a tire  150  and an air system element. The control valves  110  may be normally in (i.e. biased toward) an open position (e.g., they are normally-open valves). Alternatively or additionally, one or more of the control valves  110  can be normally in (biased toward) a closed position (e.g., a normally-closed valve). In some embodiments, one or more of the control valves  110  may be actively controlled (e.g. by a controller). Alternatively or additionally, one or more of the control valves  110  may be passively operable. For example, the control valves  110  may each include an electromechanically operable valve (e.g. a solenoid valve). Alternatively, one or more of the control valves  110  can be operable in any other way. In some embodiments, the control valves  110  each include a non-proportional valve. Alternatively, one or more of the control valves  110  can include a proportional valve, a servo valve, or any other type of valve. In one variation, the control valves  110  each include the actuator as described in U.S. Provisional Application No. 62/384,652 filed 6 Sep. 2017, which is incorporated in its entirety by this reference. 
     In some embodiments, one or more of the control valves  110  are emplaced in (e.g. arranged in) a flow path (e.g. a port) between a tire  150  and one or more air system elements, and controls fluid flow therethrough. Preferably, the control valve  110  is aligned with the flow path but can alternatively be oriented at an angle with respect to the flow path, located partially or wholly outside the flow path, or otherwise arranged. Preferably the TMS has one control valve  110  per air system element, but can alternatively have any number of control valves  110 . 
     In one variation, the control valves  110  are arranged in a manifold  160  (e.g.  FIG. 4 ). In a first example, the control valves  110  are arranged in the manifold  160  described in U.S. Provisional Application No. 62/384,652 filed 6 Sep. 2017, which is incorporated in its entirety by this reference, wherein the control valves  110  are arranged in ports, wherein each port is fluidly connected to a channel  161 . In another example, the control valves  110  are arranged in a manifold  160  without a channel  161 , wherein the fluid connections between air system elements remain separate. 
     In one variation, wherein the control valves  110  are arranged in the manifold as described in U.S. Provisional Application No. 62/384,652 filed 6 Sep. 2017, which is incorporated in its entirety by this reference, wherein the manifold has a channel  161 , there is one control valve  110  per air system element. 
     For example, and as shown in  FIG. 3C , the control valves  110  include an intake valve  111 ) which fluidly connects an air source  130  to the channel  161 . As also shown in  FIG. 3C , the control valves  110  may also include an exhaust valve  112  which fluidly connects an air sink  140  to the channel  161 . The exhaust valve  112  can be normally-open, such that the system is exhausted upon key-off. Alternatively, the exhaust valve  112  may be a normally-closed valve. The intake valve  111  can be normally-closed, such that initial system operation does not immediately pressurize the channel  161 . Alternatively, the intake valve  111  may be a normally-open valve. The intake valve  111  can selectively control the pressure in a fluidly connected third port  114   c  (connected to the tire  150 ), and thereby control a tire pressure in one or more tires  150  fluidly connected to the third port  114   c . As also shown in  FIG. 3C , the control valves  110  may also include an output control valve  113  which fluidly connects one or more tires  150  to the channel  161 . In this variation, the intake valve  111  and the output control valve  113  can be opened to inflate the tire  150 , and the exhaust valve  112  and the output control valve  113  can be opened to deflate the tire  150 . By selectively controlling the configurations of these control valves  111 ,  112 ,  113 , the tire(s)  150  can be in fluid communication with only the air sink  140  (e.g. during deflation), only the air source  130  (e.g. during inflation), both the air sink  140  and the air source  130 , or neither the air sink  140  nor the air source  130 . An example of a flow path during tire deflation is illustrated in  FIG. 5A . An example of a flow path during tire inflation is illustrated in  FIG. 5B . 
     2.7 Pressure Sensor. 
     The system can further include a pressure sensor  170 , which functions to determine a pressure parameter value in the TMS or elsewhere in the vehicle. Preferably, the pressure sensor  170  is a differential pressure sensor  170  but can alternatively be a gauge pressure sensor  170 , an absolute pressure sensor  170 , a sealed pressure sensor  170 , or any other sensor configured to determine a pressure parameter. Preferably, the pressure parameter is a pressure change rate between air system elements. Alternatively, the pressure parameter can be a pressure change rate within an element, a gauge pressure within an element, a difference in gauge pressures between elements, a pressure change acceleration, or any other suitable parameter. The pressure sensor  170  is preferably connected to and configured to measure a pressure parameter in an air system element (e.g. an air source, a tire, an air sink), but can alternatively be configured to measure a pressure parameter in a manifold (e.g. in a channel, port, etc.), between air system elements, or elsewhere. Preferably, the pressure sensor  170  is a piezoelectric material, but may be any other material or combination of materials configured to determine a pressure parameter. Preferably, there is one pressure sensor  170  per air system element, but alternatively there may be a single pressure sensor  170  or any number of pressure sensors  170  in the system. 
     In one variation, a pressure sensor  170  is arranged in a port of a manifold, wherein the pressure sensor  170  port is fluidly connected to a channel and configured to determine the value of a pressure parameter in the channel  161 . In one example, the pressure sensor  170  measures the absolute pressure of the compressed air in the channel  161 . In another example, the pressure sensor  170  measures the pressure change rate between an air source and a tire  150 . In alternative examples, the pressure sensor  170  can be arranged in any port, channel, or other part of a manifold, wherein the pressure sensor  170  can measure any pressure parameter associated with any air system element or combination of air system elements fluidly connected to said element. 
     In a second variation, the pressure sensor  170  is arranged within or elsewhere on an air system element. In one embodiment, a pressure sensor  170  is arranged within the external shell of a tire and configured to measure the absolute pressure within the tire. In a second embodiment, a first pressure sensor  170  is arranged within a first air system element (e.g. an air source) and a second pressure sensor  170  is arranged within a second air system element (e.g. a tire), wherein the pressure sensors  170  are each configured to determine a pressure parameter (e.g. absolute pressure), wherein these pressure parameters are further used to determine a secondary pressure parameter (e.g. pressure change rate). In one example, the secondary pressure parameter is determined using a controller. 
     In some embodiments, and as shown in  FIG. 3C , the system includes a pressure control module (PCM)  164 . The PCM  164  includes a pressure sensor  170  fluidly connected to and monitoring the pressure within a suspension system  163  (e.g., an air spring). In one example, the pressure sensor  170  is used to determine the load in the vehicle. However, the system can include any suitable number of pressure sensors arranged in any suitable configuration. In some embodiments, the PCM  164  also includes the manifold  160 , and one or more control valves  110  in a unitary package. 
     2.8 Electronic Control Unit. 
     The system can further include an electronic control unit (ECU)  180 , which functions to control the operation of one or more valves. The ECU  180  may include one or more microprocessors and/or microcontrollers. Additionally, the ECU  180  may include communications circuitry, such as CAN, LIN, Ethernet, etc. Additionally, the ECU  180  may include digital and/or analog output circuitry for providing power to operate one or more valves. Additionally or alternatively, the ECU  180  can function to control power provision to one or more valves in the system. Additionally or alternatively, the ECU  180  can function to control the operation of or the power provision to any element or combination of elements in the system or vehicle (e.g. a pressure sensor). In some embodiments, the PCM  164  also includes the ECU  180 . 
     The ECU  180  is preferably electrically connected to and controls the operation (e.g. position) of one or more control valves. The ECU  180  can store a vehicle condition database  185 , an error log, or any other suitable information. Alternatively, the ECU  180  can be wirelessly connected to and control the operation of one or more control valves. The ECU  180  is preferably a printed circuit board assembly (PCB), but can alternatively be a wire wrap circuit, a point-to-point soldered electrical circuit, or any other suitable configuration. In one variation, the ECU  180  is configured for wireless communication, and can include short range communication systems (e.g., NFC, Bluetooth, RF, etc.), long-range communication systems (e.g., WiFi, cellular, satellite, etc.), a vehicle networking system (e.g., CAN bus connection), or any other suitable communication system. In one example, the ECU  180  is configured to receive instructions from a driver, a fleet command center, or any other suitable control system. 
     In one variation, the ECU  180  is configured to communicate with a remote information source (e.g. lookup table, database, server, user device, vehicle network system, etc.), wherein the remote information source communicates commands for the operation of one or more control valves to the ECU  180 . In one example, the remote information source communicates a set of commands for the control valves to the ECU  180 , wherein the set of commands is determined using vehicle information such as the load (e.g., mass) value and distribution in the vehicle, the terrain conditions (e.g., current and/or anticipated), the location and orientation of the vehicle, and/or any other parameter. In another example, the remote information source is an operator at a fleet command center, wherein the operator communicates instructions to a driver through a display module coupled to the ECU  180 . 
     In one variation, the ECU  180  is an electronics module as described in U.S. Provisional Application No. 62/384,652 filed 6 Sep. 2017, which is incorporated in its entirety by this reference. In a second variation, the ECU  180  is a user device (e.g. mobile phone). In a third variation, the ECU  180  is an existing control unit (e.g. engine control unit) in the vehicle. 
     2.9 Vehicle Condition Database. 
     The system can further include a vehicle condition database  185 , which functions to store vehicle condition parameters, such as, but not limited to: operational parameters (e.g. operational modes for a control valve or a check valve), pressure parameters, tire condition (e.g. wear-and-tear) parameters, or any other parameter. Additionally or alternatively, the vehicle condition database  185  can function to inform the operation of one or more valves based on the vehicle condition parameters. For example, the vehicle condition database  185  can include a database, table, equation, or other data structure correlating a pressure or pressure rate differential to control valve operating instructions. In a second example, the vehicle condition database  185  includes a data structure (database, equation, lookup table, etc.) correlating the load magnitude and/or distribution with target tire pressures (e.g., for all or a subset of tires). In a third example, vehicle condition database  185  includes a data structure correlating a terrain parameter (e.g., incline, surface roughness, surface looseness, surface wetness, traction, etc.) with target tire pressures (e.g., for all or a subset of tires). However, the vehicle condition database  185  can include any other suitable information. 
     Preferably, the vehicle condition database  185  is communicatively coupled to a controller of the vehicle, but can additionally or alternatively be communicatively coupled to a user device of an operator of the vehicle (e.g. driver, fleet command center, etc.), or any other suitable device. The set of vehicle condition parameters preferably includes parameters related to the state of the vehicle, such as the load (magnitude, distribution, etc.) on the vehicle, vehicle ‘health’ (e.g. wear-and-tear, service reports, oil and fuel levels, etc.), and any other information related to the operation of the vehicle. Additionally or alternatively, the set of vehicle condition parameters can include parameters related to the environment of the vehicle along a route, such as, but not limited to: weather conditions (e.g. temperature, precipitation), traffic conditions, terrain conditions (e.g. road incline angle, predicted road friction, etc.), or any other conditions related to the current or proposed environment of a vehicle. Preferably, the vehicle condition database  185  is dynamically updated but can alternatively be updated at one or more discrete times, or contain static, predetermined parameters. 
     In one variation, the vehicle condition database  185  includes a lookup table, which functions inform the operational parameters of the vehicle. To perform this function, the lookup table correlates operational modes of one or more valves in the vehicle with vehicle condition parameters. Additionally or alternatively, the lookup table can correlate operational modes of other elements of the system or vehicle (e.g. vehicle key-on/off state) with vehicle condition parameters. Preferably, the correlations are determined through one or more algorithms, but can additionally or alternatively be determined through a mathematical model, through a machine learning process, by an operator, or determined in any other suitable way. In one example, the lookup table contains a set of potential arrangements of a load on a vehicle, a target pressure parameter for each tire based on that load, and an operational mode for each valve in the system, wherein the operational mode is determined algorithmically based on the target tire pressure parameters and the current tire pressures parameters. 
     2.10 Check Valve. 
     The check valve  120  functions to selectively isolate a tire from fluid connection with one or more air system elements. Preferably, the check valve  120  is fluidly connected to a tire and to a control valve, but can alternatively be fluidly connected just to a tire. Preferably, the check valve  120  is arranged upstream of a tire, but can alternatively be arranged downstream of a tire, within a tire, or otherwise arranged. The check valve  120  is preferably arranged downstream of one or more control valves, but can alternatively be arranged within a control valve, upstream of a control valve, or otherwise arranged. The check valve  120  can be passively controlled (e.g., based on pressure differentials across the valve, pressure rate changes across the valve, etc.), actively controlled by the ECU, or otherwise controlled. 
     In a first variation, the check valve  120  is a one-way check valve, arranged within the fluid manifold leading to the tire. The check valve  120  can be unidirectional (e.g., permit fluid flow in a single direction), bidirectional (e.g., permit fluid flow in both directions), or otherwise configured. In a first embodiment, the check valve can be an unloader valve that fluidly seals (e.g., upstream, toward the system) in response to the upstream pressure (e.g., system pressure) falling below the downstream pressure (e.g., tire pressure) by a threshold amount, at a rate faster than a predetermined rate, when the downstream pressure substantially matches a target pressure (e.g., a maximum tire pressure), or when any other suitable condition is satisfied. In a second embodiment, the check valve can fluidly seal downstream, toward the tire, in response to the downstream pressure falling below the upstream pressure by a second threshold amount (e.g., equal to, less than, or more than the first threshold amount), at a rate faster than the same or different predetermined rate, or when the same or different condition is satisfied. In a third embodiment, the system can include check valves of both the first and second embodiment in-line within the fluid manifold leading to the tire. 
     In a second variation, the check valve  120  is a two-way valve, but can alternatively be a three-way valve or have any number of inlet and outlet ports. Preferably, the check valve  120  defines a first combined inlet/outlet port and a second combined inlet/outlet port, wherein the first combined inlet/outlet port is fluidly connected to an upstream air system element (e.g. air source) and the second combined inlet/outlet port is connected to a downstream air system element (e.g. tire). Alternatively, the first combined inlet/outlet port is located downstream of the second combined inlet/outlet port, neither combined inlet/outlet port is located downstream of the other, or they can be arranged in any other suitable way. Preferably, the check valve  120  is a bidirectional valve, wherein the check valve  120  is configured to control flow in two directions, wherein the two directions are preferably arranged opposite to each other but can alternatively be otherwise arranged. Alternatively, the check valve  120  permits fluid connection between a tire and an air system element, and as many sealed configurations as there are directions in which the check valve  120  is configured to seal (e.g. two sealed configurations for a bidirectional valve, one sealed configuration for a unidirectional check valve  120 , etc.), wherein each sealed configuration prevents fluid connection in a specified direction between a tire and an air system element. Alternatively, the check valve  120  may be operable in only one or more sealed configurations, only an open configuration, or in any combination of open and sealed configurations. 
     Preferably, the check valve  120  is in a first sealed configuration (e.g.  FIG. 7B ) when a pressure parameter value associated with a second combined inlet/outlet port exceeds a pressure parameter value associated with a first combined inlet/outlet port by a first predetermined threshold, herein referred to as the first sealing pressure. Alternatively, the check valve  120  is normally in a first sealed configuration, is only in a first sealed configuration for a specified range of pressure parameter values, is never in a first sealed configuration, or is in a first sealed configuration at any other time. Preferably, the check valve  120  is in a second sealed configuration (e.g.  FIG. 7D ) when a pressure parameter value associated with a first combined inlet/outlet port exceeds a pressure parameter value associated with a second combined inlet/outlet port by a second predetermined threshold, herein ref erred to as the second sealing pressure. Alternatively, the check valve  120  is normally in a second sealed configuration, is only in a second sealed configuration for a specified range of pressure parameter values, is never in a second sealed configuration, or is in a second sealed configuration at any other time. Preferably, the first and second sealing pressures are equal, but can alternatively be different (e.g., the first higher than the second). In one example, the system enters a sealed configuration when the downstream pressure (e.g., tire pressure) drops below the upstream pressure (e.g., system pressure) beyond a threshold difference or faster than a threshold rate, such as in the case of a tire blowout (e.g.  FIG. 7B ). In this example, the check valve seals toward the second inlet/outlet port, and functions to isolate the tire from the rest of the system. In another example, the system enters a sealed configuration when the upstream pressure (e.g., system pressure) drops below the downstream pressure (e.g., tire pressure) beyond a threshold difference or faster than a threshold rate, such as when the vehicle is in a key-off state to prevent tire deflation (e.g.  FIG. 7D ) while the vehicle is parked or when the compressor is turned off. In this example, the check valve seals toward the first inlet/outlet port, and functions to isolate the system from the tire. Preferably, the check valve  120  is in an open configuration (e.g.  FIGS. 7A and 7C ) when the difference between a pressure parameter value associated with a first combined inlet/outlet port and a pressure parameter value associated with a second combined inlet/outlet port is below both the first and second sealing pressures. Alternatively, the check valve  120  is in an open configuration when the different in pressure parameter values is only below a single sealing pressure, when the difference in pressure parameter values is zero, check valve  120  is normally in a first sealed configuration, when the difference in pressure parameter values is within a specified range, or at any other time. Preferably, the operation of the check valve  120  is passively controlled but can alternatively be actively controlled (e.g. by the ECU  180 ). 
     In one variation, the operational mode of the check valve  120  further includes a partially sealed configuration, wherein fluid flow within the valve is partially restricted. In one example, the degree of flow restriction is proportional to the difference in pressure parameter values between valve ports. 
     Preferably, the check valve  120  (e.g.  FIG. 6 ) includes a closing element  121 , wherein engagement of the closing element  121  with an inlet/outlet port of the check valve  120  functions to restrict or prevent flow through that inlet or outlet port. Alternatively, the check valve  120  can include no closing element  121 , two closing elements  121 , or any number of closing elements  121 . Preferably, the closing element  121  is a poppet, but can alternatively be a ball, disk, diaphragm, gate, or any other element. Preferably, the closing element  121  is rubber, but can alternatively be metal, plastic, glass, compressed fluid, or any suitable material. The inlets and outlets of the check valve  120  are preferably conically tapered to retain the closing element  121 ; alternatively, the check valve  120  can have inlets and outlets with uniform cross sections or any other suitable cross section. The check valve  120  preferably further includes a compressive element  122 , wherein the compressive element  122  functions to press a closing element  121  against an inlet or an outlet port of the valve in the closed configuration. Alternatively, the check valve  120  can include only closing elements  121 . Preferably the compressive element  122  is a spring but can alternatively be a piston, a column of compressed air, or any other suitable element. Preferably each compressive element  122  in the check valve  120  has the same compressive value (e.g. spring constant), but can alternatively have different compressive values. Preferably, all the elements of the check valve  120  are enclosed within a single housing but can alternatively be split among multiple housings or not enclosed in any housing. 
     Preferably, the check valve  120  is arranged in alignment with a flow axis between a tire and an air system element. Alternatively, the check valve  120  may be arranged with an offset to the flow axis, arranged at an angle with respect to the flow axis, or otherwise arranged. 
     In one variation, the check valve  120  includes one closing element and two compressive elements. In one example, a first closing element is coupled to the first inlet/outlet port, a second closing element is coupled to the second inlet/outlet port, and the closing element is arranged between the two compressive elements. 
     In a second variation, the check valve  120  includes two closing elements and two compressive elements. In one example, the closing elements are arranged closest to the check valve  120  inlet/outlet ports with the compressive elements arranged between the closing elements. 
     In a third variation, the check valve  120  is a set of two or more unidirectional check valves  120 . In one example, the unidirectional check valves  120  are arranged in series. In another example, the unidirectional check valves  120  are arranged in parallel. 
     2.11 Mounting Mechanism. 
     The system can further include a mounting assembly, wherein the mounting mechanism  190  functions to connect all or part of the system to a vehicle. Additionally or alternatively, the mounting mechanism  190  can function to enclose any or all parts of the system, as well as other elements of a vehicle. The mounting mechanism  190  is preferably attached at a wheel assembly of a vehicle but can alternatively can be attached at any part of the vehicle (e.g. a manifold). The mounting mechanism  190  is preferably attached at the wheel assembly of a vehicle, wherein the wheel assembly includes a hubcap  195  and a tire, but can alternatively be attached elsewhere in or on a vehicle. The mounting mechanism  190  is preferably configured to be retrofittable, wherein the mounting mechanism  190  can be attached to existing attachment sites of the vehicle (e.g. a port on a hubcap  195  of the vehicle), but can alternatively require additional components for attachment, can integrated with the vehicle during manufacture, or integrated in any other suitable way. 
     The mounting mechanism  190  preferably includes a mounting conduit  196 , wherein the mounting conduit  196  functions to fluidly connect the mounting mechanism  190  to the air system of the vehicle. The mounting conduit  196  is preferably connected to an axle of a vehicle (e.g. with a barbed press-in interface), but can alternatively be connected to a hose running through an axle, a conduit outside of an axle, or to any other suitable element. The mounting conduit  196  is preferably a cylindrical shell (e.g. hose, tube), but can alternatively have an obloid cross section, a non-uniform cross section throughout its length, or any other suitable geometry. The mounting conduit  196  is preferably metal, but can alternatively be plastic, rubber, or any other suitable material. There is preferably one mounting conduit  196  per mounting assembly, but can alternatively be one mounting conduit  196  per air system element, one mounting conduit  196  per subset of air system elements, or any number and arrangement of mounting conduits. The mounting conduit  196  is preferably always open but can alternatively be partially open, partially or fully closed, or operate m any number and type of operational modes. 
     The mounting mechanism  190  can further include an attachment piece  191 , which functions to connect the mounting conduit to an axle of the vehicle. Preferably, the attachment piece  191  is configured to prevent relative rotation between the axle and the mounting conduit but can alternatively allow partial or full rotation between the axle and the mounting conduit. In one variation, the attachment piece  191  is a barbed press-in interface with spring clamp retention (e.g.  FIG. 10 ). However, the system can include any other suitable attachment piece  191 . 
     The mounting mechanism  190  can further include a rotational assembly  192 , which functions to provide a fluid connection between the mounting mechanism  190  and the tire of a vehicle. Additionally or alternatively, the rotational assembly  192  can function to enclose one or more check valves or other components. The rotational assembly  192  preferably attaches to a tire at one or tire valves (e.g. Schrader valve), but can alternatively be fluidly connected with one or more tires in any suitable way. The rotational assembly  192  preferably connects to the rest of the mounting mechanism  190  at hubcap  195 , but can alternatively connect to the rest of the mounting mechanism  190  at any other part of a wheel assembly. The rotational assembly  192  preferably includes a series of conduits  193  arranged perpendicular to the mounting conduit. Alternatively, the rotational assembly conduits  193  can be arranged at an angle with respect to the mounting conduit or in any other suitable arrangement. The rotational assembly  192  is preferably metal, but can alternatively be plastic, rubber, or any other suitable material. Preferably, the rotational assembly  192  is configured to rotate with the wheel assembly but can alternatively be configured to rotate with an offset to the wheel assembly, to not rotate at all, or to rotate in any other way. Preferably, one or more check valves is arranged in each conduit of the rotational assembly  192 , wherein the check valves are aligned with the flow axis defined by the conduit. Alternatively, there may be no check valves arranged within a conduit, or the check valves may be aligned at an angle with the conduit. 
     The rotational assembly  192  can further include a rotary union  194 , wherein the rotary union  194  functions to fluidly connect the rotational assembly  192  and the mounting conduit, wherein the rotary union  194  is configured to preserve a fluid connection between two elements having a relative rotation with each other. Preferably, the rotary union  194  is aligned with the flow axis of the mounting mechanism  190  but can alternatively be aligned with a flow axis of the rotational assembly or otherwise arranged. In one example, the rotary union  194  rotates about a stator  197  (e.g., mounting conduit), wherein the stator  197  can remain static relative to the vehicle frame. The stator  197  can terminate before, at, or beyond the bearing plane of the rotary union. The stator  197  is preferably fluidly connected (e.g., along an end, through axial holes, etc.) to the tire conduit (e.g., fluid connection extending between the stator  197  and the tire interior), which can be supported by and/or statically mounted to the rotary union, to a wheel, to the hub, or to any other suitable rotatable wheel component. The tire conduit can be a T-junction (e.g., wherein each arm can be connected to a tire), a cable, or be any other suitable fluid connection to the tire. The tire conduit can be arranged external the wheel hub, within the wheel hub, integrated with the hub, or otherwise arranged. The check valve is preferably arranged within the tire conduit, but can be arranged elsewhere. 
     In one variation, the rotary union  194  is configured to allow for misalignment, runout, and/or any other offset between the mounting conduit and the rotational assembly. An example of a rotary union  194  configured to allow for misalignment is shown in  FIG. 12 . 
     In one variation, the rotary union  194  further includes one or more seals  166  and one or more bearings  167  that function to fluidly seal the stator-tire conduit interface and facilitate assembly rotation relative to the mounting conduit. In one example, the rotary union  194  has a seal arranged around the surface of the mounting conduit, wherein the seal is arranged next to a bearing (e.g.  FIG. 10 ). In another example, the rotary union has a seal (e.g. an elastomer seal) arranged between an inner and outer bearing (e.g.  FIG. 11 ). 
     The rotational assembly  192  can further include any number and arrangement of additional components, such as but not limited to: seals, bearings, retaining rings, attachment pieces, purge channels, and housings. 
     In one variation, the mounting mechanism  190  is arranged in a tee assembly  165  (e.g.  FIG. 8 ), wherein the rotational assembly  192  is arranged along a single axis, which is oriented perpendicular to mounting conduit. In one example, shown in  FIG. 8 , the rotational assembly attaches to two tire valves. In another example, the rotational assembly attaches to one tire valve. In another example, shown in  FIG. 9 , the mounting mechanism is configured to interface with hubcaps having a 1.125-inch vent with a radial O-ring seal, the radial O-ring seal having a threaded interface to all locking and rigid clamps to interface with varying hubcap thicknesses. 
       3 . Method. 
     The method for managing a tire functions to enable dynamic control of air flow into and out of a tire. As shown in  FIG. 2 , the method includes: determining a pressure parameter value S 200 , determining an operational parameter for a valve based on the pressure parameter value S 210 , and controlling the valve based on the operational parameter S 220 . The method can further include communicating the state of the system to a remote entity S 230 . 
     The method is preferably performed by, using, and/or in cooperation with the tire management system described above. However, the method can alternatively be performed using any other suitable tire or vehicle management system, such as that disclosed in U.S. Provisional Application No. 62/384,652 filed 6 Sep. 2017, which is incorporated herein in its entirety by this reference. Additionally or alternatively, the method can be performed with a user device, a remote computing system (e.g. a server), or any other suitable computing system. 
     In one example, the method includes: determining a target deflated tire pressure; dynamically cycling a control valve, fluidly connected between the tire and an air sink, between an open and closed position (e.g., in situ, while the vehicle is in motion); monitoring a pressure change rate when the control valve is in the open position; determining control valve cycling parameters (e.g., cycling frequency, open duration) based on the pressure change rate; cycling the control valve according to the cycling parameters until the current tire pressure substantially matches the target tire pressure; and in response to upstream system exhaustion (e.g., pressure drop beyond a threshold rate), automatically (e.g., passively or actively) sealing a check valve arranged within a fluid manifold between the control valve and the tire. Alternatively, the cycling parameters can be predetermined. This example can optionally include determining an instantaneous tire pressure; determining a deflation duration based on the cycling parameters and the difference between the target tire pressure and the instantaneous tire pressure; and cycling the control valve for the deflation duration. A similar process can be used to inflate the tire in-situ, wherein the control valve can be fluidly connected between the tire and a pressurized air source. 
     3.1 Determining a Pressure Parameter Value. 
     Determining a pressure parameter value S 200  functions to assess the current state of the system. The pressure parameter can be the element pressure (e.g., compressor pressure, tire pressure, ambient pressure), a pressure differential between two or more points (e.g., pressure difference between the tire and compressor), a pressure change (e.g., the pressure increase or decrease over a period of time), a pressure change rate (e.g., how fast the pressure is increasing or decreasing), or be any other suitable pressure parameter. The pressure parameter value can be: calculated, measured, estimated, predicted, selected, or otherwise determined. Additionally or alternatively, determining a pressure parameter value functions to specifically assess the current state of a tire (e.g. overinflated, underinflated). Preferably the pressure parameter value is determined using one or more pressure sensors (e.g., as described above), but can alternatively be determined by another type of sensor (e.g. temperature sensor), a visual means (e.g. an image of a tire), a volume assessment (e.g. volume of a tire), or any other device or method. The pressure parameter value is preferably determined during the key-on state of a vehicle but can alternatively be determined during the key-off state. The pressure parameter value is preferably determined dynamically. In one variation, the pressure parameter value is determined continuously. In a second variation, the pressure parameter value is determined at a discrete set of times. In a third variation, the pressure parameter value is determined at or after the detection of a specific event (e.g. a specific terrain type, a change in vehicle load, a threshold incline level, a particular weather condition, key-on or key-off state of the vehicle, etc.). In a fourth variation, the pressure parameter value is determined upon command by an operator of the vehicle (e.g. a driver, fleet command center operator, etc.). Alternatively, the pressure parameter value can be determined at any suitable time. 
     Preferably, more than one pressure parameter value is determined at a given time. Alternatively, a single pressure parameter value or no pressure parameter value can be determined. Preferably, the pressure parameter value is determined at an air system element (e.g. a tire). Additionally or alternatively, the pressure parameter value (e.g. pressure change rate) is determined between air system elements, between an air system element and another element (e.g. atmosphere), between any suitable elements in a vehicle, or at a remote location (e.g. cloud-based server, fleet command center, etc.). Further alternatively, the pressure parameter value can be determined at any of the locations described above, or at any other suitable location. In one variation, the pressure parameter value in a manifold is determined (e.g. from a pressure sensor coupled to the channel of the manifold). 
     Determining a pressure parameter value can additionally or alternatively be performed by or in conjunction with an ECU (e.g. processor). In one variation, the pressure parameter value is determined through a calculation. In one example, the pressure parameter value is calculated as the difference between two or more pressure parameter values, wherein the two or more pressure parameter values are taken at different times and/or at different locations in the system. In another variation, the pressure parameter value is estimated using an algorithm of the ECU (e.g. a machine learning algorithm). In another variation, the pressure parameter value is approximated from another pressure parameter value (e.g. a pressure parameter value determined earlier) based on predetermined thresholds and/or models. 
     The method can further include dynamically determining, monitoring, and or/recording a pressure parameter value. 
     The method can further include determining a target pressure parameter value, wherein the target pressure parameter value can be determined from a lookup table, calculated (e.g., using a predictive model, any other suitable equation, etc.), predicted using a deep learning algorithm, retrieved from a database (e.g. vehicle condition database described above), determined by an operator of the vehicle, or otherwise determined. The target pressure parameter can be a target tire pressure, a target manifold pressure, or a target pressure associated with any element in the system or vehicle. The target pressure parameter value can include: a target pressure, a target pressurization rate, a pressurization duration, or any other target parameter. The target pressure can be predetermined, determined once, iteratively determined (e.g., based on new, up-to-date measurements), or determined at any suitable frequency or time. In one example, different load magnitudes and/or distributions can be associated with different target tire pressures (e.g., wherein the associated target tire pressures can be empirically determined, manually determined, or otherwise determined). In a second example, different pressure differences between the target tire pressure and the current tire pressure can be associated with different pressurization rates and/or durations. In a third example, different pressure differences between the current tire pressure and the air source pressure can be associated with different pressurization rates, check valve operation parameters (e.g., cycling frequencies, open duration, etc.), and/or pressurization durations. However, the target pressure parameter can be otherwise determined. 
     In one variation, a pressure parameter value is determined after activating a specified set of operational modes for one or more control valves, wherein the operation of the control valves functions to selectively isolate elements coupled to those control valves from contributing to the pressure parameter value. In one example, for instance, a pressure parameter value for the tire alone is measured in the channel by assigning a closed configuration to the control valves arranged between the channel and any element other than a tire. 
     3.2 Determining an Operational Parameter for a Valve Based on the Pressure Parameter Value. 
     Determining an operational parameter for a valve based on the pressure parameter value S 210  functions to specify a future configuration of the system. The operational parameters preferably include the operational modes of the control valves, as described above. Additionally or alternatively, the operational parameters can include the operational modes of the check valves. Further additionally or alternatively, the operational parameters can include a duration for which an operational mode persists, a transition between operational modes, a frequency (e.g. pulse repetition frequency) of the transition between operational modes, or any other parameter. 
     Preferably, the operational parameter is determined by an ECU (e.g. microcontroller), wherein the ECU is coupled to one or more valves. Alternatively, the operational parameter is determined from a remote information source (e.g. lookup table) as described above, calculated in conjunction with a remote server, predetermined by the system, predicted using machine learning, determined in accordance with another operational parameter, determined using any of the methods in S 200 , or otherwise determined. 
     S 210  is preferably performed after S 200 , but can alternatively be performed before S 200 , wherein S 200  serves as a check to see if the rest of the method can be eliminated in the absence of S 200  (e.g. when the operational parameters are predetermined), for instance. 
     In one variation, an operational parameter is determined based on a target pressure parameter value. In a first example, for instance, when the target tire pressure is higher than the current tire pressure, a control valve is assigned to operate in an open configuration, wherein the open configuration permits air flow from an air source to the tire. In a second example, wherein the pressure change rate over time is found to be constant, all the control valves in the system are assigned to operate in an open configuration. 
     In a second variation, the operational parameter includes a temporal component (e.g. a specified frequency, duration, etc.). In one example, the operational parameter for a control valve prescribes that the control valve alternates between an open and a closed configuration with a prescribed pulsing frequency during tire inflation (e.g.  FIG. 7A ), tire deflation (e.g.  FIG. 7C ), or at any other time. This operational parameter, wherein the control valve alternates between operational modes, can, for instance, maintain a low pressure differential across a check valve and function to prevent the check valve from sealing, wherein the check valve is in fluid communication with the control valve. In a second example, the operational parameter for a control valve prescribes an operational mode and a duration for which the operational mode will be assigned to the control valve. The specific duration can, for instance, be dynamically determined based on the magnitude of one or more pressure parameter values (e.g. magnitude of the pressure change rate at a tire). In another instance, the duration is predetermined. 
     The cycling frequency can be between 0.5 Hz-5 Hz, higher than 5 Hz, lower than 0.5 Hz, 2 Hz, or be any other suitable frequency. In one example, the cycling frequency and open duration per cycle can be predetermined, wherein the cycling duration can be determined based on the difference between the current tire pressure and the target tire pressure. In a second example, the larger the pressure difference between the tire and the endpoint (e.g., air source or air sink), the higher the control valve cycling frequency and shorter the open duration per cycle, wherein the cycling frequency can be lowered and/or the open duration per cycle can be shortened as the pressure difference drops. In this example, the cycling frequency and/or open duration can be selected based on the instantaneous, past, or anticipated pressure differential. In a third example, the higher the pressure change rate, the higher the control valve cycling frequency and/or shorter the open duration per cycle, wherein the cycling frequency can be lowered and/or the open duration per cycle can be shortened as the pressure change rate drops. However, the control valve operation parameters can be otherwise determined. 
     3.3 Controlling the Valve Based on the Operational Parameter. 
     Controlling the valve based on the operational parameter S 220  functions to activate a specified system configuration. The valves are preferably the control valves discussed above, more preferably the control valve fluidly connected to the tire port (e.g., the third control valve), but can alternatively be any other suitable valve. Preferably, the specified system configuration is selected based on one or more of: optimal tire performance, minimal tire wear-and-tear, and optimal vehicle safety, but can alternatively be predetermined or selected for in any suitable way by any suitable means. 
     Preferably, the valve is controlled by a controller (e.g. electronic control unit), wherein the controller is electrically connected to the valve. Additionally or alternatively, the valve can be controlled by a controller not electrically connected to the valve (e.g. processor in a user device, remote server, etc.). Additionally or alternatively, one or more valves can be passively controlled. In one variation, a valve is mechanically controlled by a pressure differential between the valve&#39;s inlet and outlet. 
     Preferably, the valves are controlled based on operational parameters determined in S 210 , but can additionally or alternatively be operated in any suitable way. Preferably, S 220  is performed after S 210 , but can additionally or alternatively be performed at any point in the method. In one variation, S 210  and/or S 220  are performed multiple times throughout the method in order to dynamically manage tire pressure during the operation of the vehicle. The valves are preferably controlled during vehicle operation (e.g., while the vehicle is in transit, being driven, etc.), but can alternatively be controlled at any other suitable time. 
     3.4 Communicating the State of the System to a Remote Entity. 
     The method can further include communicating the state of the system to a remote entity S 230 , which can function to increase vehicle safety and/or optimize vehicle performance. Preferably, the remote entity is a fleet command center (e.g.  FIG. 13 ), wherein the fleet command center manages one or more vehicles (e.g. trucks). Additionally or alternatively, the remote entity can be an operator of the vehicle (e.g. driver), a remote server (e.g. database, lookup table), a regulatory agency, or any other entity. Preferably, S 230  is a form of telematics, but can alternatively be any form of telecommunication, local communication, etc. Preferably the state of the system includes pressure parameter values, but can additionally or alternatively include operational modes of one or more valves, any of the information described above, or any other information related to the operation of a vehicle. 
     Preferably S 230  is performed with a controller of the vehicle, such as any of the controllers described above. Additionally or alternatively, S 230  is performed with a user device (e.g. a mobile device), an interactive device in the vehicle (e.g. a touchpad, button interface, voice-activated speaker system, etc.), or with any other suitable device or communication means. Examples of the user device include a tablet, smartphone, mobile phone, laptop, watch, wearable device (e.g., glasses), or any other suitable user device. The user device can include power storage (e.g., a battery), processing systems (e.g., CPU, GPU, memory, etc.), user outputs (e.g., display, speaker, vibration mechanism, etc.), user inputs (e.g., a keyboard, touchscreen, microphone, etc.), a location system (e.g., a GPS system), sensors (e.g., optical sensors, such as light sensors and cameras, orientation sensors, such as accelerometers, gyroscopes, and altimeters, audio sensors, such as microphones, etc.), data communication system (e.g., a WiFi module, BLE, cellular module, etc.), or any other suitable component 
     Additionally, S 230  can be performed in conjunction with one or more sensors (e.g. pressure sensor, accelerometer, etc.). Preferably, S 230  is performed dynamically (e.g. continuously) during the operation of the vehicle, but can alternatively be performed a single time, two or more discrete times, at the occurrence of an event (e.g. tire pressure parameter value falls below a threshold), at the prompting of the remote entity, or at any other time. 
     Preferably, S 230  includes the transmission of information (e.g. pressure parameter values, geographic coordinates, etc.) from the vehicle to a remote entity, but can additionally or alternatively include the transmission of information (e.g. operational parameters) from a remote entity to the vehicle. 
     In one variation, S 230  includes transmitting pressure parameter values to a fleet command center. In one example, the pressure parameter values are transmitted dynamically during the operation of the vehicle. In this example, the pressure parameter values are monitored at the fleet command center. If it is determined by the fleet command center that the pressure parameter values have fallen outside of a suitable range, a notification is sent to the driver of the vehicle (e.g. through a user device). Additionally or alternatively, operational commands for the control valves are sent to a controller from the fleet command center. 
     The method can optionally include probing the fluid system, which functions to determine whether the check valves between the system and each tire are open. This can be particularly useful during startup, where the check valves can be closed in the upstream direction (e.g., sealing the tire from the system due to low system pressure). Probing the fluid system can include: slowly pressurizing the manifolds connected to the tires, monitoring the pressure change in the manifold over time, counting the number of pressure drops, and ceasing manifold pressurization after the number of pressure drops matches an expected number of tires on the vehicle. Probing the fluid system can optionally include: in response to detecting a sealed valve (e.g., valve sealed in the downstream or tire-side direction), generating and/or transmitting a notification to a user device. The sealed valve can be detected in response to: pressurization beyond a threshold time duration, manifold pressure exceeding a threshold pressure (e.g., less than or equal to the first or second sealing pressure), the pressure change rising faster than a threshold rate, or otherwise detected. 
     The method can optionally include monitoring a brake system (e.g., with a secondary pressure sensor), wherein the method is performed after the brake system has been fully pressurized. The method can optionally include monitoring a fluid suspension system&#39;s pressure (e.g., with a secondary pressure sensor), and determining (e.g., calculating, estimating, selecting, etc.) a load magnitude and/or distribution based on the fluid suspension system&#39;s pressure and/or pressure distribution across the suspension lines. The fluid within the suspension system can be: a gas, a liquid, a compressible fluid, a noncompressible fluid, a Newtonian fluid, a non-Newtonian fluid, or any other suitable fluid. In one example, the air suspension system can be fluidly connected to the same fluid circuit as the TMS, brake system, and/or any other suitable fluid system. However, the system can include any other suitable set of processes. 
       FIG. 14  shows a block diagram of a tire management system (TMS)  100 , including the pressure control module (PCM)  164  configured to inflate four tires  150  in a vehicle. More specifically, the TMS  100  shown in  FIG. 14  includes the PCM  164  in fluid communication with a common header  104  that distributes air to each of the tires  150 .  FIG. 14  also shows a check valve  120 , also called a wheel end check valve (WECV) that controls fluid flow between the common header  104  and each of the tires  150 . 
     A problem with conventional central tire inflation systems can arise if one of the tires  150  has a leak, and air can flow from the other, non-leaking tires  150  air through the open WECVs  120 , pressurizing the system, and thereby masking the leak. This can occur with both normally-open and normally-closed WECVs. The PCM  164 , with its onboard pressure sensor  170 , watches system line pressure—when the non-leaking tires equalize to the leaking tire, the system pressure does not drop quickly to alert of a leaking tire—the flow rate out of the other non-leaking tires fills the system line with their pressure, trying to inflate the leaking tire which has a restriction at the WECV  120  that allows system line pressure to read the higher pressures of the non-leaking tires. This masks or hides the actual pressure of the leaking tire, and the PCM  164  cannot alert a driver/operator or fleet command (through telemetry) that there is a serious tire pressure problem. 
       FIG. 15  shows the tire pressure control system of  FIG. 14 , with a slow leak in one of the tires  150 . The present disclosure provides a novel leak detection method for detecting a slow leak in one of the tires  150 . This novel leak detection may be described as: “get out and then ramps back in.” In short, the leak detection method of the present disclosure reduces pressure in the common header  104  (i.e. it “gets out” of pressurizing the common header), and then it slowly ramps pressure back up in the common header  104  (i.e. it “ramps back in”). 
     If a slow leak is determined by the ECU  180 , the ECU  180  may commands a full system exhaust, dropping system pressure in the common header  104  to zero, and thereby closing all the WECVs  120 . The ECU  180  may then pulse the intake valve  111 , slowly ramping up system pressure in the common header  104  while monitoring the system pressure with the pressure sensor  170 —this way, the ECU  180  can see at least one of the tires  105  (e.g. the left-front (LF) tire) with a low pressure indicative of a leak, and which causes the ramping-up of the system pressure in the common header  104  to stall, once the system pressure in the common header  104  reaches a pressure equal to the pressure of the left-front tire. 
       FIG. 16  shows a first graph  250  of pressure vs time, showing the tire pressures when checking a tire pressure in a system with inflate and deflate control capabilities. The first graph  250  includes a first plot  252  and a second plot  254  showing pressures in “good” or non-leaking tires with an operating pressure of about 100 PSI. The first graph  250  also includes a third plot  256  of pressure in a leaking left-front (LF) tire. The first graph  250  also includes a fourth plot  258  of pressure in the common header  104 , as measured by the pressure sensor  170 . At time to, the left-front tire starts to leak. At subsequent time t 1  the ECU  180  reduces the pressure in the common header  104  to 0 PSI. For example, the ECU  180  may open the exhaust valve  112  and the output control valve  113  at time t 1 . After time t 1 , the ECU  180  gradually adds air to the common header  104  at a relatively low flow rate to gradually increase the fluid pressure in the common header  104  during a first time period  260 . 
     While gradually adding the air to the common header  104 , the pressure in the common header  104  stabilizes at a leak-indicative pressure  264 , which is substantially lower than the operating pressure. This stabilizing at the leak-indicative pressure  264  is caused by the common header  104  reaching the pressure of the left-front tire, causing its WECV to open, and the gradual adding air to start to pressurize the left-front tire. 
     After detecting the leak of one or more tires at the leak-indicative pressure  264 , the ECU  180  may proceed to inflate the tires by adding fluid to the common header  104  at an inflation flow rate substantially higher than the first flow rate, as shown by the a third plot  256  of pressure in the left-front tire increasing during a second time period  266 . For example, the ECU  180  may command the intake valve  111  and the output control valve  113  to a full-open position and/or to a full-open duration in response to determining the leak. 
     The control solution of the present disclosure may also be used with systems having only inflate control capability, where the system we cannot “get out” and exhaust system pressure, and where the normally-closed valves do not equalize to the leaking tire. Inflate only systems use normally closed valves, where after an inflation event we cannot “see” the actual tire pressure because the WECV closes immediately. The system also must be designed to allow system-side leaks due to rotary union leakage—so after an inflate event, system pressure will decay which will again mask a leaking tire. Our novel solution is to “ramp-in” and see the leaking tire pressure. See functional plot of inflate-only below 
       FIG. 17  shows a second graph  270  of pressure vs time, showing the tire pressures when checking a tire pressure in a system with only inflate control capability. The second graph  270  includes a fifth plot  272  and a sixth plot  274  showing pressures in “good” or non-leaking tires with an operating pressure of about 100 PSI. The first graph  270  also includes a seventh plot  276  of pressure in a leaking left-front (LF) tire. The second graph  270  also includes an eighth plot  278  of pressure in the common header  104 , as measured by the pressure sensor  170 . 
     The second graph  270  of  FIG. 17  is similar to the first graph  250  of  FIG. 16 , except the pressure in the common header  104  does not fall all the way to zero. Instead, the pressure in the common header  104  (as indicated by the eighth plot  278 ) falls only to an initial pressure p 0 , at which point the ECU  180  begins the gradual inflation process. The initial pressure p 0  is shown as being about 50 PSI, although the initial pressure p 0  can be any value that is less than a low operating pressure of the tires  150 , because the pressure in the in the common header  104  is increased from the initial pressure p 0  in order to detect a leak. 
       FIG. 18  shows a flow chart illustrating steps in a first method  300  for controlling tire pressure in a system with inflate and deflate control capabilities. The first method  300  starts at  302  and proceeds to check supply and tire pressures at step  304 . The supply pressure may be measured directly by the pressure sensor  170  in direct fluid communication with the common header  104 . Methods for checking tire pressures in the tires  150  are discussed further, below. 
     The first method  300  also determines if a leak is detected at step  306 . Methods for detecting leaks in the tires  150  are discussed further, below. 
     The first method  300  also adjusts frequency of pressure checks at step  308  and in response to detecting a leak at step  306 . For example, the ECU  180  may perform pressure checks on a more frequent basis in response to detecting a leak. The ECU  180  may be better able to monitor a leak to determine if a leak is getting worse and in need of attention. 
     The first method  300  also determines if an inflation event is needed at step  310 . For example, if the ECU  180  detects one or more tires  150  that with a pressure below a predetermined low-operating value, the ECU  180  may determine that inflation is needed. 
     The first method  300  also inflates the tires  150  at step  312  and in response to determining inflation is needed at step  310 . Step  312  may include inflating the tires  150  for a duration of time based on a difference between the pressure in the one or more tires  150  and an operating pressure value. For example, if the ECU  180  detects one or more tires  150  that with a pressure below a predetermined low-operating value, the ECU  180  may open the intake valve  111  and the output control valve  113  for a duration of time that depends on the amount of inflation required. 
     The first method  300  also determines if a fast leak is detected at step  314  and in response to determining inflation is needed at step  310 . For example, if the ECU  180  detects the system pressure, as measured by the pressure sensor  170 , decreasing by a predetermined amount over a given period of time, the ECU  180  may signal a fast leak as being detected. The first method  300  may return to step  304  in response to detecting no fast leak at step  314 . 
     The first method  300  also signals a fast leak at step  316  and in response to detecting a fast leak at step  314 . For example, the ECU  180  may light a diagnostic lamp, set a diagnostic trouble code (DTC), and/or communicate a message to a remote receiver indicating the detection of the fast leak. 
     The first method  300  also isolates the tires at step  318  and in response to detecting a fast leak at step  314 . For example, the wheel end check valves  120  may be closed to prevent air from flowing out of the non-leaking tires  150  into the common header  104  and out of a leak. 
     The first method  300  also determines if a deflation event is needed at step  320 . For example, if the ECU  180  detects one or more tires  150  that with a pressure above a predetermined high-operating value, the ECU  180  may determine that deflation is needed. 
     The first method  300  also deflates one or more of the tires  150  at step  322  and in response to determining deflation is needed at step  320 . Step  322  may include deflating the tires  150  for a duration of time based on a difference between the pressure in the one or more tires  150  and an operating pressure value. For example, if the ECU  180  detects one or more tires  150  that with a pressure above a predetermined high-operating value, the ECU  180  may open the exhaust valve  112  and the output control valve  113  for a duration of time that depends on the amount of deflation required. The first method  300  may return to step  304  after deflating the tires  150  at step  322 . 
     The first method  300  also includes idling at step  324  and in response to determining that deflation is not needed at step  320 . This step  320  may provide a periodic basis for the first method  300 . 
       FIG. 19  shows a flow chart illustrating steps in a second method  350  for controlling tire pressure in a system with only inflate control capability. 
     The second method  350  starts at  352  and proceeds to check supply and tire pressures at step  354 . The supply pressure may be measured directly by the pressure sensor  170  in direct fluid communication with the common header  104 . Methods for checking tire pressures in the tires  150  are discussed further, below. 
     The second method  350  also determines if the air supply is good at step  356 . For example, the ECU  180  may measure the pressure of an air supply. Alternatively or additionally, step  358  may include receiving a signal from a supply system, such as a controller on a compressor used as an air supply to the system. 
     The second method  350  also determines if a leak is detected at step  58 . Methods for detecting leaks in the tires  150  are discussed further, below. 
     The second method  350  also adjusts frequency of pressure checks at step  360  and in response to detecting a leak at step  358 . For example, the ECU  180  may perform pressure checks on a more frequent basis in response to detecting a leak. The ECU  180  may be better able to monitor a leak to determine if a leak is getting worse and in need of attention. 
     The second method  350  also determines if an inflation event is needed at step  362 . For example, if the ECU  180  detects one or more tires  150  that with a pressure below a predetermined low-operating value, the ECU  180  may determine that inflation is needed. 
     The second method  350  also inflates the tires  150  at step  364  and in response to determining inflation is needed at step  362 . Step  364  may include inflating the tires  150  for a duration of time based on a difference between the pressure in the one or more tires  150  and an operating pressure value. For example, if the ECU  180  detects one or more tires  150  that with a pressure below a predetermined low-operating value, the ECU  180  may open the intake valve  111  and the output control valve  113  for a duration of time that depends on the amount of inflation required. 
     The second method  350  also determines if a fast leak is detected at step  366  and in response to determining inflation is needed at step  310 . For example, if the ECU  180  detects the system pressure, as measured by the pressure sensor  170 , decreasing by a predetermined amount over a given period of time, the ECU  180  may signal a fast leak as being detected. second method  350  may return to step  354  in response to detecting no fast leak at step  366 . 
     The second method  350  also signals a fast leak at step  368  and in response to detecting a fast leak at step  366 . For example, the ECU  180  may light a diagnostic lamp, set a diagnostic trouble code (DTC), and/or communicate a message to a remote receiver indicating the detection of the fast leak. 
     The second method  350  also includes idling at step  370  and in response to determining that deflation is not needed at step  362 . This step  370  may provide a periodic basis for the second method  350 . Step  370  may also be performed in response to determining that the supply is not good at step  356 . In this way, the second method  350  may wait and periodically check for the supply to return to a “good” or functional state before performing other tasks, such as checking for leaks, and inflating, if necessary. 
       FIG. 20  shows a flow chart illustrating steps in a third method  400  for checking a tire pressure. The third method  400  may be used, for example, to determine if a leak is detected in any of the tires  150  at step  306  or at step  358 . 
     The third method  400  starts at step  402  and proceeds to pulse air into a tire control line until pressure peaks at step  404 . Step  404  may include, for example, the ECU  180  commanding the intake valve  111  and the output control valve  113  to be open to supply pressurized air from the air source  130  to the common header  104 , until the pressure in the common header  104 , as measured by the pressure sensor  170 , stabilizes at a particular value (i.e. the peak pressure). 
     The third method  400  also includes recording the peak pressure as the supply pressure at step  406 . For example, the ECU  180  may record the peak pressure resulting from step  404  as representing the supply pressure. 
     The third method  400  also includes pulsing a small amount of air into the tire supply line at step  408 . Step  408  may include, for example, the ECU  180  commanding the intake valve  111  and the output control valve  113  to be open for one or more durations to supply pressurized air from the air source  130  to the common header  104 . 
     The third method  400  also includes determining, after step  408 , if the pressure in the tire supply line (e.g. the common header  104 ) settles below the peak pressure at step  410 . If the pressure does not settle at a pressure below the peak pressure, the third method  400  may return back to step  408  and continue to pulsing another small amount of air into the tire supply line. 
     The third method  400  also includes recording a pressure below the peak pressure as a low-tire pressure at step  412  and in response to determining that the pressure in the tire supply line having settled below the peak pressure at step  410 . The third method  400  may continue out of the pressure check loop at step  414  and after step  414 . 
       FIG. 21  shows a flow chart illustrating steps in a fifth method  500  for detecting a leak in a pressure vessel of a system including a plurality of pressure vessels in fluid communication with a common header. In some embodiments, the pressure vessels may include tires installed on a vehicle. However, the fifth method  500  may be used with other types of pressure vessels, such as tanks in a tank farm. 
     In some embodiments, the common header is in fluid communication with each of the tires via a wheel-end check valve configured to allow fluid flow from the common header to a corresponding one of the tires while blocking fluid flow in an opposite direction. 
     The fifth method  500  includes reducing a fluid pressure in the common header to a first predetermined value at step  502 . The first predetermined value may be a pressure value below an operating pressure of the plurality of pressure vessels. In some embodiments, the first predetermined value may be equal to or approximately equal to an ambient air pressure. 
     In some embodiments, step  502  may include opening an exhaust valve to release fluid from the common header. For example, in an inflate/deflate type system, the ECU  180  may command the exhaust valve  112  to release air from the common header  104 . Alternatively, step  502  may include fluid leaking from the common header with no controlled valves in fluid communication with the common header being commanded open. For example, in an inflate-only type system, the ECU may wait and monitor the pressure in the common header  104  as fluid leaks therefrom. For example, air may leak out of the common header  104  from one or more rotary unions that couple the common header  104  to the tires  150 . 
     The fifth method  500  also includes gradually adding fluid to the common header at a first flow rate at step  504  to increase the fluid pressure in the common header from the first predetermined value. 
     In some embodiments, steps  502  and  504  are each performed on a periodic basis. For example, the ECU  180  may perform at least steps  502  and  504  of the fifth method  500  in order to check for leaks on a regular basis, such as daily, weekly, etc. 
     The fifth method  500  also includes monitoring, after gradually adding the fluid to the common header, the fluid pressure in the common header at step  506 . 
     In some embodiments, step  506  includes opening a proportional valve to an intermediate position to allow flow from an air source to the common header. Alternatively or additionally, step  506  may include opening a non-proportional valve for a duty cycle duration in each of a plurality of time periods to allow flow from an air source to the common header. 
     The fifth method  500  also includes determining a leak in at least one pressure vessel of the plurality of pressure vessels at step  508 , based on the fluid pressure in the common header after gradually adding the fluid to the common header. In some embodiments, step  508  includes determining the fluid pressure in the common header settling at a value below the operating pressure of the plurality of pressure vessels. 
     The fifth method  500  also includes inflating the at least one pressure vessel by adding fluid to the common header at an inflation flow rate substantially higher than the first flow rate at step  510  and in response to determining the leak in the at least one pressure vessel. For example, the ECU  180  may command the intake valve  111  and the output control valve  113  to a full-open position and/or to a full-open duration in response to determining the leak at step  508 . 
     The fifth method  500  also includes activating a diagnostic indicator at step  512  and in response to determining the leak in the at least one pressure vessel at step  508 . For example, the ECU  180  may cause an indicator light to be illuminated and/or for a message to be displayed on a display screen, indicating the detected leak. 
     The fifth method  500  also includes setting a diagnostic trouble code at step  514  and in response to determining the leak in the at least one pressure vessel. For example, the ECU  180  may set a trouble code in memory that can be subsequently read to indicate the detection of the leak. 
     The fifth method  500  also includes transmitting a message to remote receiver at step  516  and in response to determining the leak in the at least one pressure vessel. For example, the ECU  180  may cause a message to be transmitted to a fleet management system. Such a message may be transmitted via a digital communications network, such as a cellular data network and/or via the internet. 
     The system, methods and/or processes described above, and steps thereof, may be realized in hardware, software or any combination of hardware and software suitable for a particular application. The hardware may include a general purpose computer and/or dedicated computing device or specific computing device or particular aspect or component of a specific computing device. The processes may be realized in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other programmable device, along with internal and/or external memory. The processes may also, or alternatively, be embodied in an application specific integrated circuit, a programmable gate array, programmable array logic, or any other device or combination of devices that may be configured to process electronic signals. It will further be appreciated that one or more of the processes may be realized as a computer executable code capable of being executed on a machine readable medium. 
     The computer executable code may be created using a structured programming language such as C, an object oriented programming language such as C++, or any other high-level or low-level programming language (including assembly languages, hardware description languages, and database programming languages and technologies) that may be stored, compiled or interpreted to run on one of the above devices as well as heterogeneous combinations of processors processor architectures, or combinations of different hardware and software, or any other machine capable of executing program instructions. 
     Thus, in one aspect, each method described above and combinations thereof may be embodied in computer executable code that, when executing on one or more computing devices performs the steps thereof. In another aspect, the methods may be embodied in systems that perform the steps thereof, and may be distributed across devices in a number of ways, or all of the functionality may be integrated into a dedicated, standalone device or other hardware. In another aspect, the means for performing the steps associated with the processes described above may include any of the hardware and/or software described above. All such permutations and combinations are intended to fall within the scope of the present disclosure. 
     The foregoing description is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 
     Although omitted for conciseness, the preferred embodiments include every combination and permutation of the various system components and the various method processes, wherein the method processes can be performed in any suitable order, sequentially or concurrently. 
     As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims.