Abstract:
A method of balancing a wheel assembly is achieved by providing a wheel assembly which includes a tire in a range substantially between 13″ and 24.5″ size, providing pulverulent polymeric/copolymeric synthetic plastic material in a range substantially between 8-12 screen size and 40-200 screen size, and placing a selected screen size range of the pulverulent material in free movable relationship to the tire in a weight range substantially between ½ ounce to 24 ounces for the tire size ranges of substantially between 13″ to 24.5″ size.

Description:
BACKGROUND OF THE INVENTION  
       [0001]    The invention is directed to a method of balancing a vehicle wheel assembly, such as wheel assemblies of passenger and truck vehicles and aircraft. This application is a continuation of pending U.S. patent application Ser. No. 08/184,735 filed Jan. 21, 1994, herein incorporated by reference; which is a continuation-in-part of U.S. patent application Ser. No. 07/750,687 filed Aug. 27, 1991, now abandoned; which is a continuation of U.S. patent application Ser. No. 07/599,776 filed Oct. 17, 1990, now issued as U.S. Pat. No. 5,073,217. 
     
    
     
         [0002]    The related art directed to the present invention is exemplified by U.S. Pat. No. 2,909,389 in the name of John C. Wilborn which was granted on Oct. 20, 1959. In accordance with this patent, globular weights are placed in a tube which is eventually placed in a biased tire and the tire is eventually placed upon a wheel which is in turn placed upon a vehicle. When the wheel rotates, the weights are thrown against the inner surface of the outer wall of the tube, and the imbalance of the wheel is said to be corrected by the position assumed by the globular weights. This method is said to avoid the conventional method of balancing wheels of motor vehicles by crimping lead weights on the edges of the rims of the wheels and, through proper balancing, vibration of the vehicle is lessened and so, too, should be uneven wear on the tires, excessive wear on the bearings, the shock absorbers, the steering mechanism and other parts of the vehicle. The size, shape and design of the globular weights are not specified in this patent other than the obviously globular configuration best illustrated in FIG. 3. However, the same patentee had granted to him on Mar. 6, 1956, U.S. Pat. No. 2,737,420 in which a wheel is balanced by forming an annular channel in a rim into which a liquid is inserted along with globular weights. These globular weights are described in this patent as lead or steel shot. Accordingly, the patents collectively utilize globular weights of lead or steel shot per se or in conjunction with the liquid for balancing biased tires under the centrifugal force created during in-use tire rotation.  
         SUMMARY OF THE INVENTION  
         [0003]    In accordance with the method of the present invention, a wheel assembly is balanced utilizing force variations and centrifugal forces as tires rotate in use with the associated vehicles. However, in contradistinction to known prior art methods, including those of the Wilborn patents, the present balancing method utilizes forces which are present within the wheel assembly when in use and which virtually change continuously as vehicle speeds and loads change. Thus, the method seeks not simply to reduce vibration attributed to what might be loosely termed “imbalance”, but also reduces vibration caused by excessive radial run-out, or lateral tread area force variation, and does so through the utilization of granules and/or powder (pulverulent material) of specified size, weight and quantity to affect equalization of the force variations over the entire “footprint” of a tire. Thus, due to the nature, size and quantity of the pulverulent material, increased amplitude associated with greater tire-to-road impact forces the pulverulent material proportionately toward such areas to null or eliminate radial force variation and achieve load force equalization. In other words, a greater amount of the pulverulent material is forced to the areas opposite the greater impact forces whereas a lesser amount of the granules will remain in the area opposite the lesser load forces, both sidewall-to-sidewall across the footprint of the tread and, of course, circumferentially about the tire. In this fashion, irrespective of the specific load force at any point between tire and surface, eventual continuous tire rotation and tire load force variation results in displacement of the pulverulent material until all radial force variations have been equalized, thereby placing the wheel assembly in complete “balance”.  
           [0004]    The aforesaid balancing is achieved instantaneously because the pulverulent material is relatively light, free flowing and thus “moves” rapidly and continually under constant variable load forces.  
           [0005]    Furthermore, the preferred pulverulent material in the most preferred embodiment is compatible with the tire innerliners to lubricate (or at least not abrade) and thereby maintain or add resiliency to the innerliners. Normally, plasticizers within the innerliners tend to migrate out of the innerliners through the body of the tire causing degradation of the rubber resulting in increased innerliner porosity and tire sidewall cracking. Thus, the pulverulent material not only allows instant response to load force variation and impact force because of the light weight thereof, but long innerliner life and thus long tire life is also assured because of the lubricity characteristics of the polymeric resin pulverulent material.  
           [0006]    With the above, and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a fragmentary side elevational view of a conventional wheel assembly including a tire carried by a rim, and illustrates a lower portion or “footprint” of the tire tread resting upon and bearing against an associated supporting surface, such as a road.  
         [0008]    [0008]FIG. 2 is an axial vertical cross sectional view through the wheel assembly of FIG. 1 and additionally illustrates the lateral extent of the footprint when the tire rests under load upon the road surface.  
         [0009]    [0009]FIG. 3 is an enlarged cross sectional view identical to FIG. 2, and illustrates the manner in which the pulverulent material are deposited within an interior of a tire through an associated tire valve.  
         [0010]    [0010]FIG. 4 is a fragmentary cross sectional view of an apparatus for injecting the pulverulent material into the tire of FIG. 3, and illustrates a valve core removed from the tire valve incident to the injection of the pulverulent material into the tire through the air valve.  
         [0011]    [0011]FIG. 5 is a cross sectional view of the wheel assembly of FIG. 3 during rotation, and illustrates a plurality of radial load forces of different variations or magnitudes reacting between the tire and the road surface as the tire rotates, and the manner in which the pulverulent material are forced from the position shown in FIG. 3 in proportion to the variable radial impact forces.  
         [0012]    [0012]FIG. 6 is a graph, and illustrates the relationship of the impact forces to the location of the pulverulent material relative to the tire when under rolling/running conditions during balancing in accordance with FIG. 5.  
         [0013]    [0013]FIGS. 7 through 10 are graphs illustrative of the amplitude of wheel variations detected during the testing of a test vehicle under four different test conditions.  
         [0014]    [0014]FIGS. 11 and 12 are graphs which illustrate amplitude of vibration of a test vehicle and vehicle cab vibration, respectively. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Reference is first made to FIGS. 1 and 2 of the drawings which illustrate a conventional wheel assembly generally designated by the reference numeral  10  defined by a tire  11  and a metal rim  12  carrying a tire valve or air valve  13  which includes a stem  14  having an internal thread  15  (FIG. 4) to which is normally screw threaded an externally threaded conventional valve core  16 , which is illustrated, removed from the stem  14  in FIG. 4. However, under normal operating/road conditions, the valve core  16  is threaded by means of the thread  15  into the stem  14  of the tire valve  13 . The valve stem  14  also includes a conventional external thread  18 . The tire  10  is a radial tire. A biased tire essentially does not flex radially whereas a radial tire tends to flex radially and, in use, the latter can be evidenced by sidewalls SW 1 , SW 2  (FIGS. 1, 2,  3  and  5 ) which tend to bulge outwardly under load when resting or running upon a surface, such as a road R. The amount of flex will vary depending upon such things as the total load of the vehicle, the speed of the vehicle, etc., and the load force can vary from wheel assembly to wheel assembly both in smaller passenger vehicles and larger vehicles, such as tractor-trailers. For example, a fully loaded tractor-trailer traveling at sixty miles an hour carrying heavy steel has a greater radial force and, therefore, greater tire flex than the same tractor-trailer traveling unloaded, as occurs quite often in the hauling industry. Furthermore, as the load increases, the flex of the tire increases and the overall radius decreases. Obviously, if a wheel assembly was conventionally “balanced” by utilizing lead weights applied to the rims, the lead weights would be effective to achieve balancing for a particular load and for a limited speed range, but not for the fill variations in load force and all speeds. Therefore, even when wheel assemblies are balanced with today&#39;s sophisticated electronic balancing machines, the wheels are not balanced for all speeds and all radial force variations. However, in keeping with the present invention, such is the case when the radial tire  11  is balanced, as will be described more fully herein.  
         [0016]    The radial tire  11  includes a lower tire portion or a footprint B defined by a length L and a lateral breadth or width W which collectively define the instantaneous cross sectional area of the tire lower portion B in engagement with the supporting surface or road R when the wheel assembly  10  is stationary or is rotating. The tire T includes a conventional external tire tread T and beads B 1 , B 2  of the respective sidewalls SW 1 , SW 2  which engage the rim  12  in a conventional manner.  
         [0017]    If the wheel assembly  10  and similar wheel assemblies associated with a vehicle (not shown) are not properly/perfectly balanced, the attendant unbalanced condition thereof during vehicle wheel rotation will cause the tires to wear unevenly, wheel bearings will wear excessively, shock absorbers operate at inordinately higher amplitudes and speeds, steering linkages/mechanisms vibrate excessively and become worn and overall vehicle ride is not only rough and dangerous, but also creates excessive component wear of the entire vehicle. These problems are significant in automobiles, but they are magnified in association with extremely large tires, such as truck tires, which are initially very expensive and, if uncared for through unbalanced running, would adversely affect truck life, safety and, just as importantly, tire retreading. Furthermore, running an 18-wheeler or other large vehicles for hours on end, which is not uncommon in long hauling operations, causes excessive driver fatigue which, in turn, is potentially hazardous.  
         [0018]    Obviously, even if the wheel assembly  10  was balanced as perfectly as possible with lead weight, whether by static or dynamic balancing, as road conditions change, as the tire  11  wears, as the load of the vehicle changes, etc., the “perfect” balanced condition of the wheel assembly  10  is far less than perfect. Accordingly, not only must the wheel assembly  10  be balanced, but the balanced condition must be retained or must change to stay in balance in response to variations in road conditions, load forces, changes in speed, etc., as might occur in conventional utilization as, for example, in the case of a loaded versus an unloaded tractor-trailer. Thus, as forces vary during rotation of wheel assembly  10  relative to the road R, the force variations must be equalized to effect or maintaining wheel balance and load force equalization, and the response time for such balancing and load force equalization should be virtually instantaneous irrespective of the tire to road force and/or amplitude.  
         [0019]    In keeping with the present invention, the wheel assembly  10  is balanced and maintained in balance by utilizing within an interior I of the tire  11  of the wheel assembly  10 , granules and/or powder and/or dust (pulverulent material)  20 . A preferred pulverulent material is a polymeric/copolymeric synthetic material, such as POLYPUS manufactured by U.S. Technology Corporation of 220 7th Street S.E., Canton, Ohio 44702. This preferred pulverulent material  20  is polymerized urea formaldehyde thermoset resin which is available in the following size ranges:  
                       TABLE A                       Screen Size               (U.S. Standard mesh)   Millimeters   Inches                    8-12   2.13-1.68   .0937-.0661       12-16   1.68-1.19   .0661-.0469       12-20   1.68-.841   .0661-.0331       16-20   1.19-.841   .0469-.0331       20-30   .841-.595   .0331-.0234       20-40   .841-.420   .0331-.0165       30-40   .595-.420   .0234-.0165       40-60   .420-.250   .0165-.0098       60-80   .250-.177   .0098-.0070                  
 
         [0020]    The pulverulent material  20  is non-volatile, nontoxic, noncorrosive and includes the following characteristics:  
                             TABLE B                       (Physical Characteristics of Pulverulent material 20)                                    Hardness               (Barcol)   64 to 62           (MOHS Scale)   3.5           Specific Gravity (gms/cc)   1.47-1.52           Bulk Density (lbs./cu. ft.)   58-60           Maximum Operating Temperature   300° F.           Chemical Nature   Inert                      
 
         [0021]    The pulverulent material  20  is composed of polymerized urea molding compound (70% by weight), alpha cellulose filler (28% by weight) and pigments and additives (2% by weight).  
         [0022]    In addition to the screen size ranges set forth in Table A, another range of the pulverulent material  20  found particularly effective in keeping with the present invention includes the following characteristics:  
                       TABLE C                       Screen Size               (U.S. Standard mesh)   Millimeters   Inches                   40-200   .420-.075   .0165-.0029                  
 
         [0023]    This range of particle size is considered “dust”, and within the screen size range specified (40-200). Approximately 60% of the particles are in the 50-100 screen size range, namely, approximately 60% are between 0.0117-0.0059 inch or 0.300-0.150 mm. Other characteristics of the pulverulent material  20  of Table C include:  
                           TABLE D                                       Hardness               (Barcol)   54 to 62           (Rockwell)   M110-120           (MOHS Scale)   3.5           Density   At 20° C., 1.5 g/cm 3             pH Value   At 250 g/1 H 2             Ignition Temperature   530° C.           Thermal Decomposition   450° C.           Izod Impact   ASTM D256A - 0.25-0.40           Water Absorption   ASTM D570 - 24 hr. - 0.4%-0.8%               MIL-A-85891A - Max. 10%                      
 
         [0024]    A predetermined amount/weight of the pulverulent material  20  can be placed in the interior I of the tire  11  prior to the tire  11  being mounted upon the rim  12 . However, it is highly desirable to inject the pulverulent material  20  into the tire interior I after the tire  11  has been mounted on the rim  12  and to do so through the tire valve or air valve  13 . In order to accomplish the latter, an apparatus  30  (FIG. 4) is provided which includes a highly pressurized source  31  housing the pulverulent material  20  which can be filled in a conventional manner and pressurized in a conventional fashion. The pulverulent material  20  can be introduced into the tank  31  through a line  32  and a line  33  is connected to a high pressure air source or pump P. A line  34  includes a valve  35  which is connected to a threaded inlet port  36  of a nozzle  37  having an axial bore  38  and a counterbore  40  carrying an O-ring seal  41  and threads  42  which mate with external threads  18  of the valve stem  14 . A handle  43  includes a rod  44  slidable and rotatable relative to the bore  38  and sealed relative thereto by another O-ring seal  45  carried by the nozzle  37 . A lower end portion  46  of the rod  44  is bifurcated and mates with conventional slots (unnumbered) of the valve core  16 . Suitable means (not shown) are provided to prevent the handle  43  and rod  44  from being retracted (upwardly) beyond the position illustrated in FIG. 4. If the valve core  16  is threaded in the stem  14  by virtue of the threaded engagement between the threads  19  of the valve core  16  and the threads  15  of the stem  14 , the handle  43  can be rotated clockwise to unthread the valve core  16 . When the threads  15 ,  19  are totally disengaged, air pressure within the tire interior I will push the valve core  16  and the handle  43  to the maximum outward position thereof shown in FIG. 4 which places the inlet port  36  in free communication with the bore  38  and, of course, with the interior I of the tire  11  through the stem  14 . The valve  35  is opened and since the pressure with the tank or source  31  is greater than that in the tire interior I (which can be as low as zero), the pulverulent material  20  will flow through the conduit  34 , the inlet port  36 , the bore  38  and the stem  14  into the tire interior I and will deposit therein a pile or mound M (FIG. 3). The precise amount/weight of the powder deposited in the tire interior I can be regulated quite readily and simply as, for example, by first determining the pressure within the tire interior I, increasing the pressure over the line  33  a substantial amount beyond that in the interior I, and opening the valve  35  for a predetermined time period such that the over pressure in the tank  31  injects the precise weight of granules  20  considered appropriate to balance the particular size tire  11  involved. Once the injection of the pulverulent material  20  has been completed and the valve  35  has been closed, the handle  43  is pushed downwardly and the valve core  16  is again threaded into the stem  14  via the threads  19 ,  15 . This process is, of course, repeated with each tire  11  of each wheel assembly  10  of the particular vehicle involved, and once completed the vehicle is then merely driven along the road R whereupon each wheel assembly  10  is rotated and the load force or radial force variation is equalized, consequently a complete wheel assembly balancing occurs, as will be described immediately hereinafter.  
         [0025]    Reference is made to FIGS. 5 and 6 which illustrate the innumerable radial impact forces (Fn) which continuously react between the road R and the tread T at the lower portion or footprint B during wheel assembly rotation. There are an infinite number of such forces Fn at virtually an infinite number of locations (Pn) across the lateral width W and the length L of the footprint B, and FIGS. 5 and 6 diagrammatically illustrate five such impact forces F 1 -F 5  at respective locations P 1 -P 5 . As is shown in FIG. 6, it is assumed that the forces F 1 -F 5  are different each from each other because of such factors as tire wear at the specific impact force location, the road condition at each impact force location, the load upon each wheel assembly, etc. Thus, the least impact force is the force F 1  at location P 1  whereas the greatest impact force is the force F 2  at location P 2 . Once again, these forces F 1 -F 5  are merely exemplary of innumerable/infinite forces laterally across the tire  11  between the sidewalls SW 1  and SW 2  and circumferentially along the tire interior which are obviously created continuously and which vary as the wheel assembly  10  rotates. As these impact forces are generated during wheel assembly rotation, the pulverulent material  20  relocates from the mount M (FIG. 3) in dependency upon the location and the severity of the impact forces Fn. The relocation of the pulverulent material  20  through movement of the individual granules, powder and dust is also inversely related to the magnitude of the impact forces. For example, the greatest force F 1  (FIG. 6) is at position P 1 , an due to these greater forces F 1 , the pulverulent material  20  is forced away from the point P 1  and the least amount of the pulverulent material remains at the point P 1  because the load force thereat is the highest. Contrarily, the impact force F 2  is the lowest at the impact force location point P 2  and therefor more of the pulverulent material  20  will remain thereat (FIG. 5). In other words, at points of maximum or greatest impact forces (F 1  in the example), the quantity of the pulverulent material  20  is the least, whereas at points of minimum force impact (point P 2  in the example), the quantity of pulverulent material  20  is proportionally increased creating lift therefore equalizing the radial force variations. Accordingly, the vibrations or impact forces Fn force the pulverulent material  20  to continuously move away from the higher or excessive impact areas F 1  or areas of maximum imbalance F 1  and toward the areas of minimum impact forces or imbalance F 2 . The pulverulent material  20  is moved by these impact forces Fn both laterally and circumferentially, but if a single force and a single granule of the pulverulent material  20  could be isolated, so to speak, from the standpoint of cause and effect, a single granule located at a point of maximum impact force Fn would be theoretically moved 180° therefrom. Essentially, with an adequate quantity of pulverulent material  20 , the variable forces Fn create through the impact thereof a lifting effect within the tire interior I which equalizes the radial force variation applied against the footprint until there is a total balance circumferentially and laterally of the complete wheel assembly  11 . Thus the rolling forces created by the rotation of the tire assembly  10  in effect create the energy or force Fn which is utilized to locate the pulverulent material  20  to achieve lift and balance and assure a smooth ride. Furthermore, due to the characteristics of the pulverulent material  20 , road resonance is absorbed as the wheel assemblies  10  rotate.  
         [0026]    The effectiveness of the present invention and the utilization of the pulverulent material  20  to balance wheel assemblies was tested utilizing a GMC Series 7000 stake body truck with a load of nine tons. The body truck was fitted with a vibration transducer on the right front axle and vibration data was taken using a CSI Spectrum Analyzer. The front tires were Firestone 11R22.5, the tire pressure was 90 psi, and 24 oz. of the pulverulent material  20  in the 20-40 Screen Size Range (Table A) were placed in the tire interior I. Four runs were made and each test was made on a normal concrete highway with the truck speed being held as close as possible to 60 mph for five to seven minutes as the data was taken and averaged. The road surface was dry, and the outside temperature was 72° F.  
         [0027]    The four test runs were:  
         [0028]    1—the truck as received without pulverulent material  20  added thereto;  
         [0029]    2—the truck as received with 24 oz. of lead added to the right front wheel but without pulverulent material  20  in the tire thereof;  
         [0030]    3—the pulverulent material  20  was added to each front tire in the size and amount foresaid, and the 24 oz. lead was left on the right front wheel; and  
         [0031]    4—the 24 oz. lead was removed from the right front wheel and the pulverulent material  20  was left in each tire interior.  
         [0032]    Spectral plots of the average readings in mils (1 mil=0.001″) for each of the test runs were:  
                                                   Test Runs   Amplitude                           Test Run 1 - As received   17.57 mils           Test Run 2 - 24 oz. added right front   32.90 mils           Test Run 3 - Pulverulent material added   19.16 mils           Test Run 4 - 24 oz. removed    6.93 mils                      
 
         [0033]    It is significant to note that the pulverulent material  20  (Pul.) reduced wheel vibration measurably, particularly in Test Run 4 in which all lead weight was removed. It is also apparent that the amount of the pulverulent material  20  added to the tires for the test runs was equivalent to approximately  15  mils or 22 oz. of lead at the wheel rim. A comparison between Test Run 1 and Test Run 4 evidences a remarkable lessening of vibration and, thus, a complete wheel assembly balance. But just as significant is the fact that even with the 24 oz. of lead left on the right front tire (Test Run 3) but with the pulverulent material  20  added, there was a significant reduction in amplitude (19.16 mils) as compared to Test Run 2 in which the right front wheel had the 24 oz. of lead weight but none of the pulverulent material therein.  
         [0034]    In addition to the four test runs, additional tests were conducted at the test track of the Transportation Research Center at Marysville, Ohio. Several vehicles were used for these tests including a loaded tractor-trailer unit, a transit bus, and an Oldsmobile Calais. The test track of the Transportation Research Center is a seven mile track which made it possible to maintain a constant speed and to take the data for each test run over exactly the same stretch of roadway.  
         [0035]    A vibration transducer was attached to the right front axle of each of the vehicles, and vibration data was taken and averaged over the same five mile track length. Each of the test vehicles was accelerated to 65 mph, unless otherwise noted hereinafter, and vibration data was recorded for five minutes starting at the same location of the test track. The data was stored in a Teac MR 30 FM Data Recorder and then analyzed and averaged using a CSI Spectrum Analyzer. The average vibration in mils (1 mil=0.001″) over the five miles for each of the test vehicles and for each of the test conditions/runs per vehicle is as follows:  
                                             VEHICLE 1       LOADED TRACTOR-TRAILER                                Test Run 1   As Received   20.8       Test Run 2   24 Oz. Lead Weight Added   55.9       Test Run 3   24 Oz. Lead Weight + 8 Oz. 20-40 Pul. Mat. 20   31.8       Test Run 4   24 Oz. Lead Weight + 12 Oz. 20-40 Pul. Mat. 20   29.7       Test Run 5    8 Oz. 20-40 Pul. Mat. 20 Only   19.4       Test Run 6   12 Oz. 20-40 Pul. Mat. 20 Only   12.7                  
 
         [0036]    [0036]                                             VEHICLE 2       TRANSIT BUS                                Test Run 1   As Received   10.5       Test Run 2    6 Oz. Weight Added   15.1       Test Run 3    6 Oz. Weight + 12 Oz. 20-40 Pul. Mat. 20   8.8       Test Run 4   12 Oz. 20-40 Pul. Mat. 20 Only   6.4                    
         [0037]    [0037]                                             VEHICLE 3       OLDSMOBILE CALAIS                                Test Run 1   As Received   20.8       Test Run 2   Spin Balance All Tires   55.9       Test Run 3   1 Oz. 20-40 Pul. Mat.   31.8       Test Run 4   1 Oz. 20-40 Pul. Mat. 20-75 MPH   29.7       Test Run 5   1 Oz. 20-40 Pul. Mat. 20-80 MPH   19.4                    
         [0038]    [0038]FIG. 11 is a spectral plot illustrating the difference between the vibration at wheel frequency with 24 oz. of lead added to the front wheel of the tractor-trailer and with and without the pulverulent material  20 . The 24 mil reduction in vibration due to the addition of the pulverulent material  20  is clearly evident.  
         [0039]    An interesting result of the addition of the pulverulent material  20  is shown in FIG. 12. The low frequency cab vibration (below 2 Hz) was reduced by more than 500 mils when the pulverulent material  20  was added to the wheels with the 24 oz. lead weights.  
         [0040]    The data indicates a reduction in the vibration at wheel frequency in all of the three vehicles tested.  
         [0041]    Accordingly, in accordance with the method described specifically heretofore, applicant has provided a novel method of continuously internally equalizing radial and lateral load force variations of a complete wheel assembly through utilizing the unequal amplitude generated internally of the tire across the footprint of the tread area thereof to force pulverulent material of a predetermined size, weight and volume which will respond instantaneously to these forces. This will create a lift at a 180° area from the increased amplitudes of the wheel assembly which will totally equalize the force variation of the entire wheel assembly. Consequently, 360° of the wheel assembly as well as the footprint tread area will all meet the road surface equally, hence, creating a totally smooth vibration-free ride. The same footprint (tread area) forces are also utilized to equalize the lateral forces across the width of the tread area causing the entire lateral area to meet the road surface equally. Hence, load force, lateral force and radial force variations are all “balanced” in keeping with the novel method of this invention.  
         [0042]    Although a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the method without departing from the spirit and scope of the invention as defined in the appended claims.