Patent Publication Number: US-2021178816-A1

Title: Systems and methods for forming a multi-core semi-pneumatic tire

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to the field of semi-pneumatic tires. More specifically, and without limitation, this disclosure relates to multi-core semi-pneumatic tires and methods for forming the same. The tires and formation techniques disclosed herein may be used in various applications and systems, such as lawnmowers, automotive vehicles, and other systems that benefit from semi-pneumatic tires. 
     BACKGROUND 
     Semi-pneumatic tires typically comprise rubber surrounding a hollow core filled with air. The hollow core is an empty chamber that is intentionally formed within the body of the tire when it is manufactured and is not further pressurized with air. Unlike pneumatic tires, the hollow core is sealed during vulcanization and does not include any valves or bladders for refilling air in the core. Nevertheless, the hollow core is generally small enough such that the tire may continue to be used for a period of time after the tire has been punctured, e.g., before the tire needs to be replaced due to any shape deformity caused by continued use of the punctured tire. Accordingly, semi-pneumatic tires are often referred to as “run-flat” tires. 
     Existing constructions of semi-pneumatic tires are generally limited in size to widths (e.g., sidewall to sidewall) of 6.5 inches or less. One solution to this problem developed by Michelin® is an airless tire, marketed as a Tweel®, comprising a hub connected to the rim via flexible polyurethane spokes. Michelin&#39;s Tweel tires, however, are generally more costly than other conventional semi-pneumatic tires and are not cost-effective for applications such as industrial mowing or other high-mileage uses. 
     SUMMARY 
     Embodiments of the present disclosure overcome the disadvantages of the prior art by providing multi-core semi-pneumatic tires and methods for forming such semi-pneumatic tires. By including multiple cores, the semi-pneumatic tires of the present disclosure may exceed the size limitations of existing semi-pneumatic tires, for example, having sizes up to or exceeding approximately 6.5 inch widths for tires with two hollow cores and even larger diameters for semi-pneumatic tires having more than two cores, such as up to or exceeding approximately 12 inch widths, 26 inch widths, or greater. The multi-core semi-pneumatic tires of the present disclosure are also more cost-effective compared with existing airless tires, such as the Tweel®. 
     Further, embodiments of the present disclosure provide methods for manufacturing multi-core semi-pneumatic tires. For example, by extruding rubber to form multiple hollow cores within the body of a semi-pneumatic tire, embodiments of the present disclosure can reduce the manufacturing time and costs compared with traditional semi-pneumatic tire-manufacturing processes. In some exemplary embodiments, the semi-pneumatic tire is constructed comprising two or more continuous hollow cores that extend in parallel around substantially the entire length of the tire&#39;s circumference. In such exemplary embodiments, adjacent parallel cores may be separated from each other within the tire by one or more rubber walls formed by the extruding process. Further to these exemplary embodiments, a method for manufacturing such a multi-core semi-pneumatic tire is also provided. 
     Additional objects and advantages of the present disclosure will be set forth in part in the following detailed description, and in part will be obvious from the description, or may be learned by practice of the present disclosure. The objects and advantages of the present disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
     It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the disclosed embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which comprise a part of this specification, illustrate several embodiments and, together with the description, serve to explain the principles and features of the disclosed embodiments. In the drawings: 
         FIG. 1A  is a schematic representation of an exemplary multi-core semi-pneumatic tire, according to certain embodiments of the present disclosure. 
         FIG. 1B  is a cross-section of the exemplary semi-pneumatic tire of  FIG. 1A  showing a plurality of cores, according to certain embodiments of the present disclosure. 
         FIG. 2  is another schematic representation of multiple cores for an exemplary semi-pneumatic tire, according to certain embodiments of the present disclosure. 
         FIG. 3A  is a schematic representation of an exemplary extrusion apparatus with a mandrel that may be used for forming a multi-core rubber strip for a multi-core semi-pneumatic tire, according to certain embodiments of the present disclosure. 
         FIG. 3B  is a schematic representation of an exemplary process for forming a semi-pneumatic tire using a multi-core rubber strip, according to certain embodiments of the present disclosure. 
         FIG. 4A  is a schematic representation of an exemplary semi-pneumatic tire with three cores, according to certain embodiments of the present disclosure. 
         FIG. 4B  is a schematic representation of an exemplary semi-pneumatic tire with four cores, according to certain embodiments of the present disclosure. 
         FIG. 5  is a flowchart of an exemplary method for forming a multi-core semi-pneumatic tire, according to certain embodiments of the present disclosure. 
         FIG. 6  is a flowchart of another exemplary method for forming a multi-core semi-pneumatic tire, according to certain embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosed embodiments provide multi-core semi-pneumatic tires and methods for manufacturing the same. Advantageously, the exemplary embodiments disclose semi-pneumatic tire designs and manufacturing processes that can be more cost-effective for producing larger-width semi-pneumatic tires than is conventionally possible, such as tires with widths greater than 26 inches, or greater than 12 inches or at least greater than 6.5 inches. Embodiments of the present disclosure may be implemented and used in various applications and systems, such as but not limited to lawnmowers, automotive vehicles, golf carts, powersport vehicles, and any other vehicles or systems that may benefit from semi-pneumatic tires. Although exemplary embodiments of the present disclosure are generally described with reference to a single tire, it will be appreciated that the multi-core semi-pneumatic tires described in this disclosure may be part of, or integrated with, a larger assembly, such as containing at least one wheel, axel, or other component of a vehicle. 
     According to an aspect of the present disclosure, a semi-pneumatic tire may comprise a plurality of cores. In the exemplary embodiments, a “core” may refer to a hollow volume that extends along a circumferential direction of the tire. For example, a core may encompass the whole circumference of the tire. Also, as disclosed in the exemplary embodiments, the cores may be provided in any suitable size and shape for the tire. The multi-core tires of the exemplary embodiments are “semi-pneumatic” because each of their plurality of cores does not include any valves or other mechanisms for inserting pressurized air into the cores. Accordingly, the cores of the tires may be sealed from an environment external to the tire. 
     Additionally, in some embodiments, each core in the multi-core tire may be insulated from one or more adjacent cores by a material, such as rubber or a rubber-like material, that preferably may be formed within the body of the tire using an extruding process. For example, the same material that is used to form the outer portions and/or bulk of the tire also may be used to form one or more walls, partitions, diaphragms, or other separators between adjacent cores within the tire. In some embodiments, the material used to form the tire and its internal separators between adjacent cores preferably comprises any natural or synthetic rubber, including but not limited to isoprene polymers, chloroprene polymers, isobutylene polymers, styrene polymers, butadiene polymers, or any combination thereof. Accordingly, as used herein, the term “rubber-like” material refers to any natural or synthetic rubber material, including but not limited to the examples above. 
     According to another aspect of the present disclosure, a method for forming a semi-pneumatic tire using an extrusion process is described. For example, the method may include extruding a material, such as a rubber-like material, through a mold. In some exemplary embodiments, the mold preferably is shaped having a circular cross-section, where “circular” in this context may refer to a circle, an oval, an ellipse, or any other geometry with one or more rounded corners. The circular shape of the mold may enable the cross-section of the tire to be formed by extruding a rubber-like material through the mold. The extruded material may comprise a strip or other linear shape after it is extruded. In accordance with some embodiments, the extruded material may include a plurality of hollow volumes along its length for forming multiple cores when the strip or linearly shaped extruded material is further formed into a generally circular tire configuration. 
     To provide the multiple cores within the tire, in some embodiments the method may include inserting a plurality of hollow sections within the cross-section of the extruded material using a plurality of mandrels. Additionally or alternatively, the mold may include a plurality of mandrels held in place with legs or other supports. In any such embodiments, the extruded rubber-like material may include a plurality of hollow cores corresponding to the positioning of the plurality of mandrels. For example, if the extruded rubber-like material comprises a strip or other linear shape after extrusion, the hollow cores may extend along a length of the strip. 
     In embodiments where the extruded rubber-like material includes small gaps or holes corresponding to the positions of legs or other supports in the mold that impinge into the extruded material, the method may further include vulcanizing the extruded rubber-like material to seal such gaps or holes. For example, the material may be vulcanized using heat and/or chemicals such as sulfur. 
     In any of the exemplary embodiments described above, the manufacturing method may further include sealing the distal ends of the extruded rubber-like material together to form a circular shaped tire in which each of the plurality of hollow cores extends along a circumference of the tire. The process of sealing the ends of the extruded material together to form the tire also may comprise a vulcanization process using heat and/or chemicals such as sulfur. In some exemplary embodiments, the vulcanization process used to seal the distal ends of the extruded material together to form a circular shaped tire may employ the same vulcanization process that is also used to seal small gaps in the extruded material, as described above, or may employ a different vulcanization process. 
     Additionally or alternatively, sealing the distal ends of the extruded material to form the circular tire configuration may comprise using one or more adhesives. For example, one or more rubber-based adhesives may seal the distal ends together, either permanently or before vulcanization. 
       FIG. 1A  is a schematic representation of an exemplary tire  100 , consistent with certain embodiments of the present disclosure. As shown in the example of  FIG. 1A , tire  100  includes an outer surface  101  configured to contact the ground (not shown) as the tire rotates. Moreover, tire  100  also includes an inner surface  103  configured to contact a wheel (not shown) around which tire  100  is wrapped. In some embodiments, tire  100  may further include one or more beads  105  along the outer edges of the inner surface  103  to secure the tire  100  to the wheel, e.g., along a rim of the wheel. In other embodiments not shown in  FIG. 1A , inner surface  103  may contact the wheel directly without the use of beads  105 . 
       FIG. 1B  depicts a cross-sectional view of tire  100  along axis Y, consistent with certain exemplary embodiments. As shown in  FIG. 1B , tire  100  comprises at least two cores  107   a  and  107   b  between inner surface  103  and outer surface  101 . Beads  105  are shown as a front bead  105   a  and a back bead  105   b  in the cross-section of  FIG. 1B , although any number of beads, or even no beads, may be used. 
     Cores  107   a  and  107   b  may comprise residual air that has been trapped in each core during the manufacturing process of forming the tire  100 , e.g., using one or more of the exemplary manufacturing processes of  FIGS. 5 and 6 . Although depicted with two cores (see also  FIG. 2 ), the tire  100  alternatively may include any number of two or more cores, such as three cores as shown in  FIG. 4A , or four cores as depicted in  FIG. 4B , or more cores. 
     Moreover, cores  107   a  and  107   b  may comprise irregular shapes, for example, to fit the shape of a particular wheel. For example, as  FIG. 1B  shows, the exemplary cores  107   a  and  107   b  may have at least one dimension (e.g., height) that is longer near the center of tire  100  and shorter near the edges of tire  100 . In other embodiments, the cores  107   a  and  107   b  may comprise circular shapes, e.g., as depicted in  FIG. 2 , rectangular shapes, or any other cross-sectional shapes. The shapes and positions of each core within the tire  100  may be separately selected, for example, based on a typical load that may be applied to the tire, a desired weight for the tire, and/or other environmental or operational factors that may be specific for a particular application or system using the tire. 
       FIG. 2  is a schematic representation of a semi-pneumatic tire  200  that includes a plurality of cores, consistent with certain embodiments of the present disclosure. As shown in the example of  FIG. 2 , the tire  200  may include at least two cores  201   a  and  201   b ; however, in other embodiments, tire  200  may include additional cores, such as three cores as depicted in  FIG. 4A , or four cores as depicted in  FIG. 4B , or more. In this example, the cores  201   a  and  201   b  of  FIG. 2  may correspond to the cores  107   a  and  107   b  in  FIG. 1B . Further, in some exemplary embodiments, the cores  201   a  and  201   b  have substantially the same shapes and the position of these cores may be substantially symmetric about the center of the tire&#39;s cross-sectional area (e.g., depicted as axis Y in  FIGS. 1A and 1B ). 
     In the example of  FIG. 2 , both the tire  200  and its cores  201   a  and  201   b  have circular cross-sections. Accordingly, the curvatures of rounded corners  205   a  and  205   b  of the tire  200  may comprise multiples, fractions, or other functions of the curvatures of the rounded corners  203   a  and  203   b  of the cores  201   a  and  201   b , respectively. Although not labeled in  FIG. 2 , the curvatures of additional rounded corners of tire  200  may similarly comprise multiples, fractions, or other functions of the curvatures of additional rounded corners of cores  201   a  and  201   b.    
     Additionally or alternatively, as shown in  FIG. 2 , the spacing between cores  201   a  and  201   b  as well as the spacing between the cores and an outer surface of tire  200  may comprise multiples, fractions, or other functions of each other. In the example of  FIG. 2 , the spacing between cores  201   a  and  201   b  is equal to the spacing between surfaces of cores  201   a  and  201   b  and nearby outer surfaces of tire  200 . In other embodiments, these spacings need not be equal but instead may be any multiple, fraction, or other function of each other. 
     Although not depicted in  FIG. 2 , additional dimensioning may include selecting the lengths (not including the rounded corners) of cores  201   a  and  201   b  as fractions or other functions of the length (not including the rounded corners) of tire  200 . Additionally or alternatively, additional dimensioning may include selecting the heights (not including the rounded corners) of cores  201   a  and  201   b  as fractions or other functions of the height (not including the rounded corners) of tire  200 . 
       FIG. 3A  depicts an exemplary extrusion process  300  for forming a multi-core semi-pneumatic tire, e.g., tire  100  of  FIGS. 1A and 1B , tire  200  of  FIG. 2 , or the like, consistent with certain embodiments of the present disclosure. As shown in the example of  FIG. 3A , a rubber-like material  303  is forced through mold  301  to form a strip or other linear shape of extruded material. Moreover, mandrel  305 , for example attached to a dummy block  307 , forms a core within the rubber-like material  303  as the material is extruded through mold  301  and around the mandrel  305 . In this example, a ram or piston  309  may control the speed and relative movement of the dummy block  307  and therefore control the movement of the mandrel  305 . Those skilled in the art will appreciate other extruding apparatuses and systems could be used as an alternative to the example of  FIG. 3A . 
     In other embodiments (not shown in  FIG. 3A ), for example, the mandrel  305  may comprise a floating mandrel protruding from a slot in the dummy block  307 . In such embodiments, the speed of mandrel  305  may be controlled independently from the speed of the ram or piston  309 . 
     As an alternative to the use of a fixed or floating mandrel  305 , some embodiments may incorporate the mandrel  305  into the mold  301  using legs or other supports. These legs or supports may result in small gaps or hollow spaces in the extruded rubber-like material  303  such that the hollow core formed by the mandrel  305  may not be sealed. Accordingly, to form a semi-pneumatic tire with a sealed core, any small gaps that may have been formed by the legs in the extrusion process may be closed using a vulcanization process, e.g., as discussed with respect to  FIG. 3B  or by using a separate and additional vulcanization process. 
     Although described with respect to a single core, the techniques shown in  FIG. 3A  and discussed herein with reference to  FIG. 3A  may be used to form any number of cores. For example, additional mandrels  305  may be incorporated during the extrusion process to form additional cores, e.g., using a different mandrel  305  for each hollow core that is formed as the rubber-like material is extruded. 
       FIG. 3B  depicts an exemplary molding process  350  for converting an extruded material having multiple cores into a circular configuration to form a semi-pneumatic tire, e.g., such as the tire  100  of  FIGS. 1A and 1B , tire  200  of  FIG. 2 , or the like, consistent with certain embodiments of the present disclosure. The process  350  may be used after the extrusion process  300  of  FIG. 3A . As shown in the example of  FIG. 3B , a strip of rubber-like material having multiple cores formed using an extrusion process may have two distal ends  351   a  and  351   b . The strip of rubber-like material may be formed into a circular shape and ends  351   a  and  351   b  aligned and joined. Joining the ends  351   a  and  351   b  will form the circular shaped tire with an inner surface and outer surface and may be sealed using adhesives and/or a vulcanization process to close off the cores from the environment. Accordingly, residual air in the cores may be trapped during the process of joining the distal ends  351   a  and  351   b . In other embodiments, a vacuum or partial vacuum may be applied to the cores before and/or during joining of the ends  351   a  and  351   b . In yet other alternative embodiments, one or more of the cores may be filled with a polymeric foam or other material to provide additional structural or load-bearing support. 
     As discussed above, the process of joining the ends  351   a  and  351   b  together may include use of one or more adhesives, such as rubber-based adhesives, optionally also using a vulcanization process using heat and/or chemicals such as sulfur. Although not depicted in  FIG. 3B , the extruded rubber-like strip may be wrapped around a circular mold or a wheel prior to application of adhesive(s) and/or vulcanization to secure the alignment and shape of the tire before the ends  351   a  and  351   b  are joined to form the tire. In such embodiments, the circular mold (not shown) may set the circular shape for the resultant tire. The ends  351   a  and  351   b  are preferably aligned so the multiple cores within the rubber-like material form continuous hollow cores around the tire after the ends  351   a  and  351   b  have been joined together to form the tire. 
       FIG. 4A  is a schematic representation of an exemplary semi-pneumatic tire  400  with three cores, consistent with certain embodiments of the present disclosure. As shown in the example of  FIG. 4A , a tire  400  may include at least three cores  401   a ,  401   b , and  401   c . As depicted in  FIG. 4A , cores  401   a ,  401   b , and  401   c  may form a line along a cross-section of tire  400 ; however, in other embodiments, cores  401   a ,  401   b , and  401   c  may form a triangular or other shape on the cross-sectional area of tire  400 . While the exemplary cores  401   a ,  401   b , and  401   c  are shown with substantially the same cross-sectional areas, other embodiments (not shown) may select different cross-sectional areas for these cores, for example, where the central core  401   b  may have a different cross-sectional area than the outer cores  401   a  and  401   c.    
     In the example of  FIG. 4A , both the tire  400  and cores  401   a ,  401   b , and  401   c  have circular cross-sections. Accordingly, the curvatures of rounded corners  405   a  and  405   b  of tire  400  may comprise multiples, fractions, or other functions of the curvatures of rounded corners  403   a ,  403   b , and  403   c  of cores  401   a ,  401   b , and  401   c , respectively. Although not labeled in  FIG. 4A , the curvatures of additional rounded corners of tire  400  may similarly comprise multiples, fractions, or other functions of the curvatures of additional rounded corners of cores  401   a ,  401   b , and  401   c.    
     Additionally or alternatively, as shown in  FIG. 4A , the spacing between cores  401   a ,  401   b , and  401   c  as well as the spacing between the cores  401   a ,  401   b , and  401   c  and an outer surface of tire  400  may comprise multiples, fractions, or other functions of each other. In the example of  FIG. 4A , the spacing between cores  401   a ,  401   b , and  401   c  is equal to the spacing between surfaces of cores  401   a ,  401   b , and  401   c  and nearby outer surfaces of tire  400 . In other embodiments, these spacings need not be equal but instead may be any multiple, fraction, or other function of each other. 
     Although not depicted in  FIG. 4A , additional dimensioning may include selecting the lengths (not including the rounded corners) of cores  401   a ,  401   b , and  401   c  as fractions or other functions of the length (not including the rounded corners) of tire  400 . Additionally or alternatively, additional dimensioning may include selecting the heights (not including the rounded corners) of cores  401   a ,  401   b , and  401   c  as fractions or other functions of the height (not including the rounded corners) of tire  400 . 
       FIG. 4B  is a schematic representation of an exemplary semi-pneumatic tire  450  with four cores, consistent with certain embodiments of the present disclosure. As shown in the example of  FIG. 4B , tire  450  may include at least four cores  451   a ,  451   b ,  451   c , and  451   d . As depicted in  FIG. 4B , cores  451   a ,  451   b ,  451   c , and  451   d  may form a rectangular shape on a cross-section of tire  450 ; however, in other embodiments, cores  451   a ,  451   b ,  451   c , and  451   d  may form a linear or other shape on the cross-section of tire  450 . 
     In the example of  FIG. 4B , both a tire  450  and cores  451   a ,  451   b ,  451   c , and  451   d  have circular cross-sections. Accordingly, the curvatures of rounded corners  455   a  and  455   b  of tire  450  may comprise multiples, fractions, or other functions of the curvatures of rounded corners  453   a ,  453   b ,  453   c , and  453   d  of cores  451   a ,  451   b ,  451   c , and  451   d , respectively. Although not labeled in  FIG. 4B , the curvatures of additional rounded corners of tire  450  may similarly comprise multiples, fractions, or other functions of the curvatures of additional rounded corners of cores  451   a ,  451   b ,  451   c , and  451   d.    
     Additionally or alternatively, as shown in  FIG. 4B , the spacing between cores  451   a ,  451   b ,  451   c , and  451   d  as well as the spacing between the cores  451   a ,  451   b ,  451   c , and  451   d  and an outer surface of tire  450  may comprise multiples, fractions, or other functions of each other. In the example of  FIG. 4B , the horizontal and vertical spacings between cores  451   a ,  451   b ,  451   c , and  451   d  are equal to the spacing between surfaces of cores  451   a ,  451   b ,  451   c , and  451   d  and nearby outer surfaces of tire  450 . In other embodiments, these spacings need not be equal but instead may be any multiple, fraction, or other function of each other. 
     Although not depicted in  FIG. 4B , additional dimensioning may include selecting the lengths (not including the rounded corners) of cores  451   a ,  451   b ,  451   c , and  451   d  as fractions or other functions of the length (not including the rounded corners) of tire  450 . Additionally or alternatively, additional dimensioning may include selecting the heights (not including the rounded corners) of cores  451   a ,  451   b ,  451   c , and  451   d  as fractions or other functions of the height (not including the rounded corners) of tire  450 . 
     Although  FIGS. 4A and 4B  depicts examples of three- and four-core semi-pneumatic tires, embodiments of the present disclosure may include further cores, such as five, six, or even more cores. The sizes of tires formed according to the present disclosure may increase in proportion to the number of cores used. 
     Any of the semi-pneumatic tires described herein may be formed according to suitable manufacturing processes. For example,  FIG. 5  is a flowchart depicting an exemplary method  500  for manufacturing a semi-pneumatic tire, e.g., any of the tires in  FIG. 1A, 1B, 2, 4A , or  4 B. At step  501 , method  500  may include extruding a rubber-like material through a mold, e.g., as depicted in  FIG. 3A . The mold may be shaped with a circular cross-section, e.g., such as the cross-sections of tire  200  of  FIG. 2 , tire  400  of  FIG. 4A , tire  450  of  FIG. 4B , or the like. 
     In some embodiments, the rubber-like material used in the extrusion process of step  501  may comprise any natural or synthetic rubber. For example, the rubber-like material may comprise one or more of isoprene polymers, chloroprene polymers, isobutylene polymers, styrene polymers, or butadiene polymers. In some embodiments, the rubber-like material may comprise monomers of isoprene, chloroprene, isobutylene, styrene, and/or butadiene that are polymerized (and/or co-polymerized) during vulcanization, e.g., in step  505  of method  500 . 
     At step  503 , method  500  may include creating a plurality of hollow cores within a cross-section of the extruded rubber-like material using a plurality of mandrels. Each mandrel may be used to form a respective hollow core. For example, as depicted in  FIG. 3A , a plurality of mandrels fixed to a dummy block used for the extrusion of the rubber-like material may form the plurality of hollow sections during extrusion. Accordingly, in such embodiments, step  503  may include aligning fixed mandrels on the dummy block along desired locations for the plurality of hollow sections on the rubber-like material. 
     In other embodiments, a plurality of mandrels in a slot of a dummy block used for the extrusion of the rubber-like material may form the plurality of hollow sections during extrusion. Accordingly, in such embodiments, step  503  may include aligning floating mandrels on the dummy block along desired locations for the plurality of hollow sections on the rubber-like material and controlling the floating mandrels independently of a ram moving the dummy block. 
     In some exemplary embodiments, method  500  may further include piercing the extruded rubber-like material before inserting the plurality of mandrels. The piercing may be performed using a separate device or apparatus. Those skilled in the art will also appreciate that the mandrels may be replaced with any other suitable component that may be used to create the hollow cores in the extruded rubber-like material in accordance with the exemplary embodiments herein. 
     At step  505 , method  500  may include wrapping the extruded strip of rubber-like material around a circular mold or wheel, aligning the distal ends of the strip, including for example the hollow cores formed in the extruded material, and joining the distal ends together to form a circular shaped tire with multiple cores. In this manner, each of the plurality of hollow cores in the extruded material may extend along a circumference of the circular tire. For example, as described with reference to  FIG. 3B , vulcanizing the distal ends of the extruded material may comprise placing the extruded rubber-like material in a tire mold and using at least one of heat or chemicals to cure the extruded rubber-like material. Additionally or alternatively, step  505  may include sealing the ends of the extruded rubber-like material together using one or more adhesives. For example, step  505  may include using the one or more adhesives before using at least one of heat or chemicals to cure the material. 
     The exemplary method  500  also may include additional steps. For example, in some embodiments, method  500  may include inspecting the tire, e.g., using x-rays, magnetic resonance imaging (MRI), or the like. Additionally or alternatively, method  500  may include performing one or more mechanical tests on the tire, such as stress tests, tread tests, road tests, or the like. 
       FIG. 6  is a flowchart depicting another exemplary method  600  for manufacturing a semi-pneumatic tire, e.g., any of the tires depicted in  FIG. 1A, 1B, 2, 4A , or  4 B. Method  600  may be used as an alternative to or in combination with method  500 , in any of the exemplary embodiments described below or any combinations of such embodiments. 
     At step  601 , method  600  may include extruding a rubber-like material through a mold. The mold may be shaped with a circular cross-section, e.g., such as the exemplary cross-sections of the tire  200  of  FIG. 2 , tire  400  of  FIG. 4A , tire  450  of  FIG. 4B , or the like. The mold may further include a plurality of mandrels held in place with one or more legs. 
     In some embodiments, the rubber-like material used in the method  600  may comprise any natural or synthetic rubber. For example, the rubber-like material may comprise one or more of isoprene polymers, chloroprene polymers, isobutylene polymers, styrene polymers, or butadiene polymers. In some embodiments, the rubber-like material may comprise monomers of isoprene, chloroprene, isobutylene, styrene, and/or butadiene that are polymerized (and/or co-polymerized) during vulcanization, e.g., in step  505  of method  500 . 
     At step  603  in  FIG. 6 , method  600  may include vulcanizing the extruded rubber-like material to seal small gaps or holes in the extruded rubber-like material based on where one or more legs or other supports impinged the extruded material during the extrusion process. For example, vulcanizing to seal such small gaps or holes may comprise using at least one of heat or chemicals to cure the extruded rubber-like material. 
     At step  605 , the method  600  may include sealing the distal ends of the extruded rubber-like material together to form a circular shaped tire. After the ends have been joined together, each of a plurality of hollow cores formed by the plurality of mandrels may extend along a circumference of the tire. For example, sealing the ends of the extruded material may comprise using one or more adhesives to connect the ends. Additionally or alternatively, as depicted in  FIG. 3B , step  605  may include placing the extruded rubber-like material in a circular tire mold or wheel and using at least one of heat or chemicals to cure the extruded rubber-like material. For example, step  605  may include using the one or more adhesives before using at least one of heat or chemicals to cure the material. 
     Step  605  may include a vulcanization process distinct from step  603 . Alternatively, steps  603  and  605  may comprise the same vulcanization process. 
     Methods  500  and  600  may be combined. For example, method  600  may include step  505  of method  500  in addition with or in lieu of step  605  for connecting the ends of the extruded rubber-like material together. Similarly, method  500  may include step  505  of method  500  in addition with or in lieu of step  605  for connecting the ends of the extruded rubber-like material together. 
     The foregoing description has been presented for purposes of illustration. It is not exhaustive and is not limited to precise forms or embodiments disclosed. Modifications and adaptations of the embodiments will be apparent from consideration of the specification and practice of the disclosed embodiments. For example, the described implementations include certain exemplary manufacturing components and apparatuses, but systems and methods consistent with the present disclosure can be implemented with other manufacturing apparatuses, including for example both hardware and software. In addition, while certain components have been described as being coupled to one another, such components may be integrated with one another or distributed in any suitable fashion. 
     Moreover, while illustrative embodiments have been described herein, the scope includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alterations based on the present disclosure. The elements in the claims are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the present specification or during the prosecution of the application, which examples are to be construed as nonexclusive. Further, the steps of the disclosed methods can be modified in any manner, including reordering steps and/or inserting or deleting steps. 
     The features and advantages of the disclosure are apparent from the detailed specification, and thus, it is intended that the appended claims cover all systems and methods falling within the true spirit and scope of the disclosure. As used herein, the indefinite articles “a” and “an” mean “one or more.” Similarly, the use of a plural term does not necessarily denote a plurality unless it is unambiguous in the given context. Words such as “and” or “or” mean “and/or” unless specifically directed otherwise. Further, since numerous modifications and variations will readily occur from studying the present disclosure, it is not desired to limit the disclosure to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the disclosure. 
     Other embodiments will be apparent from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the specification and examples be considered as example only, with a true scope and spirit of the disclosed embodiments being indicated by the following claims.