Non-pneumatic tire for a track system

Abstract

A non-pneumatic tire for use as a midroller in a track system, the non-pneumatic midroller including a rim and an elastomeric portion partially encapsulating the rim, where the elastomeric portion of the midroller further includes multiple apertures disposed radially outward from the rim, the multiple apertures extending in the axial direction.

Description

[0001] NON-PNEUMATIC TIRE FOR A TRACK SYSTEM

[0002] FIELD

[0003] This disclosure relates to non-pneumatic tires for track systems, and, more generally, to vehicles such as agricultural vehicles or industrial vehicles.

[0004] BACKGROUND

[0005] Track systems are used in a variety of industries, particularly in off-road vehicles needing high traction. These can include construction vehicles (loaders, excavators, etc.) and military vehicles (tanks) and agricultural vehicles (tractors, sprayers, etc). Track systems may enhance traction and / or flotation on soft, slippery, and / or irregular grounds.

[0006] Track systems may comprise a track module. The track module comprises a frame, a drive wheel rotatably mounted to the frame, a leading and a trailing idler wheel, and a midroller (or bogie) wheel. A circular (often referred to as “endless” or “continuous”) flexible track extends around the wheels.

[0007] A track system supports a tracked vehicle. The vehicle load is transferred from the vehicle to the track module, passing from the frame to the wheels, to the track, and then from the track to the ground. The track module may comprise multiple midrollers, with most or all of the vehicle load being supported by the midrollers as they contact the inner periphery of the track. The track is therefore compressed by the midrollers.

[0008] Track vehicles may be massive. As such, each midroller may create high levels of compressive stress on the track. These compressive stresses may be exacerbated by packaging constraints (the desire to have small midrollers) and wheel fatigue constraints which lead to the use of metallic wheels. A metal wheel does not deflect, meaning that all deflection occurs within the track. Small, rigid wheels combined with high loads create high localized compressive track stresses. Elastomeric tracks may be expensive. A track may weigh several hundred kilograms and comprise multiple plies of reinforcement within a rubber matrix. Each midroller creates a cyclic stress on the track as the track vehicle moves, resulting in a large variation in track internal strain energy. This in turn creates a driving solicitation for crack propagation. As such, the track may be prematurely damaged and removed from service.

[0009] Improving track durability may be challenging. The compressive stress from the midroller cannot easily be reduced, as this stress is directly related to the load. The load may be imposed from customer requirements. Increasing the size of the midroller(s) and / or increasing the number of midrollers may be difficult, due to packaging constraints. It may be possible to improve track durability by adding more reinforcement plies or improving the fatigue characteristics of the rubber matrix, but this may increase the track cost. An innovation, therefore, in track system design is needed.

[0010] SUMMARY

[0011] According to an aspect of the invention, there is provided a non-pneumatic tire for use as a midroller in a track system, the non-pneumatic tire comprising an outer radial extent comprising a conical profile, the conical profile having a largest circumference offset from the tire centerline towards the outer lateral extent. When the tire is loaded to a design load on an inner periphery of a track, a contact width is at least 75% the width of a crown width; in other cases at least 80%; in other cases at least 85%; and in other cases 90%. The ratio of the largest circumference towards the outer lateral extent to the smallest circumference towards the inner lateral extent is at least 1.01 ; in other cases, it is at least 1 .02; in other cases, at least 1 .03, and in other cases even more.

[0012] According to an aspect of the invention, there is provided a track system, the track system comprising a non-pneumatic tire as a midroller, the non-pneumatic tire comprising an outer radial extent comprising a conical profile, the conical profile having a largest circumference offset from the tire centerline towards the outer axial extent. The track system further comprises an endless track, the track comprising a plurality of reinforcing plies. An axial extent of any one of the plies is 20 mm or more from an axial extent of the track.

[0013] According to an aspect of the invention, there is provided a non-pneumatic tire for use as a midroller in a track system, the non-pneumatic tire comprising a rim, the tire further comprising an elastomeric portion, the rim being partially encapsulated by the elastomeric portion. The elastomeric portion further comprises a plurality of apertures disposed radially outward from the rim, the apertures extending in the axial direction.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A detailed description of embodiments is provided below, by way of example only, with reference to the accompanying drawings, in which:

[0016] FIG. 1 is a side view of a track system comprising an NPT as a midroller.

[0017] FIG. 2 is a perspective view of a track system comprising an NPT as a midroller.

[0018] FIG. 3 shows an exemplary NPT for use as a midroller.

[0019] FIG. 4 is a side view of the exemplary NPT.

[0020] FIG. 5 shows a transverse crown profile of the exemplary NPT.

[0021] FIG. 6 defines a crown width of an NPT.

[0022] FIG. 7 shows a transverse profile of an NPT according to an aspect of the invention.

[0023] FIG. 8 shows an aperture profile of the exemplary NPT.

[0024] FIG. 9 shows alternative apertures for NPTs according to aspects of the invention.

[0025] FIG. 10 shows another alternative aperture embodiment for NPTs according to aspects of the invention.

[0026] FIG. 11 shows a rim for the exemplary NPT.

[0027] FIG. 12 shows the rim of FIG. 11 as it is encapsulated in the NPT.

[0028] FIG. 13 shows a closeup of a lateral extent of the NPT and rim. FIG. 14 shows an alternative rim design that is not encapsulted.

[0029] FIG. 15 is a midroller according to prior art.

[0030] FIG. 16 is a transverse profile of the midroller according to prior art.

[0031] FIG. 17 is a schematic of a track design.

[0032] FIG. 18 shows an end view schematic of a track reinforcement ply.

[0033] FIG. 19 shows an elevated view schematic of a track reinforcement ply.

[0034] FIG. 20 provides FEA results of a track subjected to a homogeneous pressure.

[0035] FIG. 21 shows FEA results of a track loaded by an NPT according to the invention midroller.

[0036] FIG. 22 shows FEA results of a track loaded by a prior art midroller.

[0037] FIG. 23 shows FEA of a contact patch on a track for an NPT midroller.

[0038] FIG. 24 shows FEA of a contact patch on a track for a prior art midroller.

[0039] FIG. 25 shows measured contact patch areas for an NPT and a prior art midroller.

[0040] FIG. 26 shows internal track damage after testing using prior art midrollers.

[0041] FIG. 27 shows internal track damage after testing using NPT midrollers. FIG. 28 shows a tension based NPT for use as a midroller according to an aspect of the invention.

[0042] FIG. 29 is a rim for an NPT that comprises a thermoplastic resin.

[0043] DEFINITION OF TERMS

[0044] The following terms are defined as follows for this disclosure, with material properties referring to those at ambient temperature, unless otherwise noted:

[0045] The rotational axis of a tire or wheel is the line about which the tire or wheel rotates. The rotational axis is parallel to the “Y” coordinate shown in the drawings. “Radial” or the letter “R” refers to the outward direction from the rotational axis and is perpendicular to the rotational axis and is parallel to the coordinate axis “Y”. The “Y” coordinate direction is also referred to as “axial” direction and “lateral” direction. The “circumferential” direction, shown by a curved line in FIG. 3, is the direction perpendicular to the plane formed by the radial axis “R” and the rotational axis “Y”, generally running longitudinally around the tire as shown in FIG. 3

[0046] “Hub” refers to any structure for supporting the tire and capable of attachment to a vehicle axle.

[0047] The “vertical” direction is shown in FIG. 2 and as used herein is perpendicular to the axis of lateral direction “Y”. The “longitudinal” direction, shown in FIG. 2 as the “X” axis, is the direction perpendicular to the lateral direction and the vertical direction. These coordinates are shown as the component coordinates as defined in FIG. 2. The positive “X” direction is the direction of usual vehicle travel, while the positive “Z” direction is usually considered “up”.

[0048] The “transverse profile” of a crown profile of a midroller is the profile of the outer radial extent of the midroller in the R - Y plane.

[0049] When referring to an elastomer, “modulus” means Young’s tensile modulus of elasticity measured per ASTM D638. The tensile modulus may be calculated as the secant modulus at a tensile strain of 0.5%. When referring to an elastomer, “dynamic shear modulus” (G*) refers to the modulus measured in a dynamic measurement analysis (DMA) at 1 % shear strain, 10 HZ, and standard temperature of 23C, unless otherwise noted.

[0050] When referring to a reinforced thermoplastic elastomer, “modulus” means Young’s tensile modulus of elasticity measured perASTM D638. The tensile modulus may be calculated as the secant modulus at a tensile strain of 0.2%.

[0051] “Design Load” of a tire is operating load of the tire when the track system is loaded to a maximum load.

[0052] Tire vertical force vs. deflection and footprint measurements may be performed according to SAEJ2704.

[0053] “Midroller” refers to a wheel position in a track system as shown in FIG. 1.

[0054] “Idler wheel” refers to a wheel position in a track system as shown in FIG. 1 .

[0055] DETAILED DESCRIPTION OF EMBODIMENTS

[0056] FIG. 1 shows a track system 100 comprising an undercarriage frame 130, an endless track 110, a plurality of midrollers 200 and a plurality of idler wheels 300. The track system 100 may be designed such that most or all of the track system load is supported by the midrollers 200. The track may comprise drive lugs 120 which extend inwardly from the inner surface of the track, located near a track centerline. The track 110 may further comprise a tread and tread blocks which extend outwardly from the track 110.

[0057] FIG. 2 shows a perspective view of the track system 100. Each midroller 200 has an outer side 210 which is oriented towards a lateral extent of the track 110. Each midroller has an inner side 220 which is oriented towards the track centerline. In general, the inside side of the midroller may be adjacent to a drive lug of the track 110.

[0058] FIG. 3 shows an exemplary midroller 200 according to an aspect of the invention. The midroller is a non-pneumatic tire (NPT). The NPT comprises an elastomeric body 230 and a rim 250. The elastomeric body may comprise a plurality of apertures 240 extending in the axial direction (shown here as “Y”). The aperture may extend from one lateral extent to the other lateral extent. The rim may be partially encapsulated by the elastomeric body. The outer radial extent of the elastomeric body defines a transverse profile 250 in the R-Y plane. The transverse profile contacts the inner periphery of the track.

[0059] FIG. 4 shows a side view of the NPT. In this exemplary example, the elastomeric body apertures 240 extend across the lateral extents of the elastomeric body. Vehicle mounting apertures 270 are provided in the rim 250 for mounting to a vehicle.

[0060] FIG. 5 shows the transverse profile 260 of the NPT 200. The profile has a width WCROWN which is considered the width that may contact the track which the NPT is loaded to a design load. Further, this exemplary profile is conical, in other words, the NPT here is shown to have a tapered transverse profile. The profile is asymmetric, with the largest circumference offset from the centerline by dom, towards the outside side of the NPT. For this exemplary profile, the width of the contact area may equal WCROWN. The centerline 280, shown here as a dashed line along the outer surface of the tire, is positioned within a centerline plane, where the centerline plane is perpendicular to the rotational axis of the tire. The largest circumference is measured about the rotational axis of the tire. The largest circumference also has the largest radius from the centerline, shown here as Rout. The smallest circumference has the smallest radius and is shown here as Rin.

[0061] In some cases, NPTs may be designed with a transverse profile that is curvilinear near the axial extents, as shown in FIG. 6. In this case, the WCRO N is defined as the lateral distance from a point on the profile tangent to a line that is inclined 30 degrees from the axial direction to a similar point on the opposite lateral extent. The largest circumference and the smallest circumference are measured at points within the WCROWN.

[0062] The inventors have done extensive numerical and empirical testing of compliant NPTs used as midrollers in a track system. Such testing and results will be disclosed in subsequent sections.

[0063] Based on their work, the inventors have determined that, according to an aspect of the invention, an outer radial extent of an NPT used in a track system may comprising a conical profile, the conical profile having a largest circumference offset from the tire centerline 280 towards the outer lateral extent. When the tire is loaded to a design load on an inner periphery of a track, a contact width is at least 75% the width of a crown width; in other cases at least 80%; in other cases at least 90%; and in other cases 100%. The ratio of the largest circumference towards the outer lateral extent to the smallest circumference towards the inner lateral extent is at least 1 .01 ; in other cases, it is at least 1 .02; in other cases, at least 1 .03, and in other cases even more.

[0064] Particularly, in the case of the exemplary NPT of FIG. 5, WCROWN = 132 mm. A contact patch width at a design load equals 132 mm, giving a ratio of 100%. For this NPT, douT = 35 mm. Also, ROUT = 173.5 mm and RIN = 168.5 mm. The ratio of ROUT I RIN = 1 .03.

[0065] In some cases, the largest circumference may be coincident with an outer lateral extent 210 of the crown profile 260, as shown in FIG. 7.

[0066] The inventors developed a methodology for measuring the contact patch width of a midroller in a track system. The method is easy to employ and will enable a person of ordinary skill in the art to determine the ratio of a contact width to crown width WCRO N , when the midroller is loaded to a design load:

[0067] 1 . Load a track system to a design load

[0068] 2. Apply a 25 mm - 35 mm strip of red Rust-oleum multipurpose spray paint laterally across an inner periphery of a track in the track system, at a longitudinal (X) location immediately adjacent to a midroller of the track system. The lateral extents of the paint strip should be wider than the lateral extents of the midroller.

[0069] 3. Within 30 seconds, move the track system in the X direction at low speed, less than 0.5 kph, until that the midroller completely traverses the paint strip.

[0070] 4. Stop the track system.

[0071] 5. Dismount the midroller

[0072] 6. Measure the width of the red paint on the crown of the midroller. This is the contact patch width.

[0073] An exemplary aperture profile 245 is shown in FIG. 8. For ease of disclosure, FIG. 8 uses a cartesian coordinate system X-Y, defined such that the origin falls on the rotation axis of the NPT. The Y axis is coincident with the radial axis and the X axis is parallel to the X axis as defined in FIG. 3. The profile may comprise a radially outward segment between points P1 and P2 following a radial equilibrium curve, such that: y = yi-cix2

[0074] In this exemplary example, yi = 156 mm and ci = 0.22. These values depend on the size of the aperture and the radial position of the aperture. Furthermore, in this case, the aperture is symmetric with respect to the y axis.

[0075] Using a radial equilibrium curve as the aperture path on the outer radial extent of the aperture enables the elastomer body to carry load in compression. Elastomers carry load in compression much more efficiently than in shear.

[0076] Through numerical modeling as well as reduction to practice, the inventors have found that apertures which follow a radial equilibrium curve over a significant percentage of the total aperture height HTOTAL may resist cracking during operation. Particularly, when the ratio of HEQ to HTOTAL is at least 0.15, performance is optimized; in other cases, 0.20; and in other cases, at least 0.30. The exemplary aperture of FIG. 8 (which is identical to the aperture comprised in the exemplary NPT of FIG. 3) has HTOTAL = 24mm and HEQ=6.0 mm, for a ratio of 0.25.

[0077] FIG. 9 and FIG. 10 shows alternative aperture profiles 246, 247. The scope of this invention is meant to include any suitable aperture profile - generally square, polygonal, circular, with multiple rows of apertures possible also.

[0078] The elastomer body may be supported by a rim. An exemplary rim design is shown in FIG. 11 . The rim 400 has a radially inward flange 410 extended in the R-q plane which is perpendicular to the rotational axis of the tire and a radially outward flange 420 extended in the q direction which is a direction parallel to the rotational axis of the tire. The radially outward flange 420 may be partially or completely encapsulated by the elastomer body. The outward flange may comprise apertures 430 which facilitate complete encapsulation during the forming operation. These apertures extend in the radial direction. The radially inward flange possesses a plurality of mounting apertures 470 for mounting to a vehicle.

[0079] FIG. 12 shows the NPT with a cut-away view such that the rim 400 intersection with the elastomer body 230 is clearly seen.

[0080] FIG. 13 shows an axial extent of the rim. Being fully encapsulated, an axial extent of the elastomer body extends farther than the rim’s axial extent. The elastomer body is unsupported by the rim over a distance of DBODY_RIM. The inventors have found this design feature to be useful in reducing track stress, as it creates a compliance near the lateral extents of the NPT. Through numerical modeling and reduction to practice, the inventors have found that DBODY_RIM should be at least 15mm; in other cases, at least 20 mm; and in other cases, even more. The DBODY_RIM of the exemplary NPT of FIG. 3 is 23 mm.

[0081] In some instances, it may be advantageous to have a rim 401 that is not encapsulated, as shown in FIG. 14.

[0082] FIG. s 15 and 16 show a prior art midroller. The crown profile is not conical, although it is assymetric. The rim is not encapsulated. There are no apertures. The design comprises a high modulus polyurethane tread that is molded onto a steel rim. As such, this midroller is very rigid.

[0083] FIG. 17 shows a schematic of a track design along with an orientation of a conical NPT 101 according to an aspect of the current invention. The NPT circumference is smallest on the inner side 220 toward the drive lug 607 of the track 606 and largest on the outside 210. In this exemplary track design, there are 5 plies that each comprise steel cables. A schematic of a ply architecture is provided in FIG. 18 and FIG. 19. Each ply 700 is described by a cable 710 cross section shown in FIG. 18, a bias angle shown in FIG. 19 with respect to the track circumferential direction, and a distance from an axial extent. Using the nomenclature provided in FIGS. 17, 18 and 19, the exemplary track ply structure has:

[0084] Table 1

[0085] Historically, tire design has assumed a flat (level) contact surface. At face value, this would seem to be an appropriate assumption for a non-pneumatic tire to be used as a midroller. The inner periphery of the track is level, i.e., the surface is parallel to ground. The track is deformable, but a priori there is no reason to think of it as not being level.

[0086] However, the inventors decided to test this assumption. They constructed an FEA model of a track and applied appropriate boundary conditions related to track tension and ground contact. Then, the inventors applied a homogeneous pressure of 1.3 bar over an area that approximated what a compliant midroller would attain. The total area was defined such that the pressure x area = 15,000 N, which was the design load for one NPT midroller.

[0087] Results are shown in FIG. 20. Quite surprisingly, the area subjected to the uniform pressure deformed with a strongly asymmetric profile. The vertical deflection near the drive lug was about 4 mm, while the deflection near the track outer edge was about 8 mm. The inventors theorized that a conical, compliant tire would be required to produce a homogeneous pressure on the track surface. As an ideal design goal, a homogeneous pressure would result in minimizing the maximum track pressure, which in turn reduces cyclic interior track stress and strain. This in turn reduces heat buildup. These important performance parameters are explained in subsequent sections. The inventors have found that certain industrial and practical constraints contribute to the track conical deformation when subjected to a homogeneous pressure. As shown in FIG. 17, none of the reinforcing plys extend to the lateral extents of the track. Industrial tolerances for ply end placement necessitate a considerable space between the edge of the track and the end of the ply. Obviously, the track is relatively unsupported at the edge, which contributes to the conical deformation.

[0088] As such, a conical NPT midroller design may be useful for optimizing the performance of a track that is most easily industrialized. As such, an aspect of the invention is: an NPT comprising a conical transverse profile used as a midroller in a track system comprising reinforcing plies. An axial extent of any one of the plies is 20 mm or more from an axial extent of the track.

[0089] The preceding sections have disclosed specific aspects of the invention. Now, the inventors disclose specific theory used in concept creation as well as numerical and empirical results.

[0090] A cyclic change in shear stress and produces heat according to Equation 1 :

[0091] Where: q = heating due to viscoelastic loss f = frequency of the stress and strain oscillation

[0092] 8= loss angle

[0093] <J= oscillating stress amplitude

[0094] E= elastomer modulus

[0095] Furthermore, cracks propagate within a rubber elastomer according to Equation 2: Where: k and a are material-dependent constants

[0096] G = strain energy release rate ctcr

[0097] — = crack propagation rate per cycle

[0098] Strain energy release rate is directly related to strain energy density as defined in Equation 3 for simple mode 1 solicitation:

[0099] Where: SED = strain energy density a = crack length

[0100] For rubber, prior art references give the exponent a in Equation 2 as approximately equal to 2.0 for natural rubber and 4.0 for styrene-butadiene rubber Combined with Equation 3, it is clear that crack propagation may vary with the stress amplitude raised to the fourth or even the eight power. Therefore, even moderate reductions in oscillating stress due to midroller contact may give large improvements in track fatigue life, as well as reductions in track operating temperature.

[0101] From Equation (1 ), reducing oscillating stress amplitude also reduces heat buildup. Thus, reducing midoller stress applied on a track may reduce operating temperature as well as crack propagation.

[0102] The inventors employed parametric FEA in the design of NPT midrollers and track systems, resulting in the design disclosed in FIG. 3. A range of material properties were considered for the elastomeric body. An exemplary material was Lanxess thermoset polyurethane B836. At 60C, 10 HZ, 1 % shear strain, this elastomer has a dynamic shear modulus of about 17 MPa and a tan(d) of about 0.04. Through experimentation, the inventors have determined that the elastic body elastomer should have a dynamic shear modulus of no more than 21 MPa; in some cases, no more than 17 MPa, and in some cases, even less. Furthermore, the tan(d) of the elastic body elastomer at 60C should be no more than 0.09; in other cases, no more than 0.07, and in other cases even less.

[0103] When loaded on the deformable track, FEA predicted contact patch shapes for NPT midrollers contact patch shape 800 and prior art midrollers contact patch shape 810 shown in FIG. 23 and 24 respectively. The NPT midroller had a larger contact area and therefore a lower average contact pressure as shown in FIG. 23. The NPT contact pressure average was 1.47 MPa, while the prior art midroller was 2.14 MPa. The ratio of NPT pressure to prior art pressure is 0.69. Employing Equation 2, taking a = 2, and setting crack propagation rate of a track with a prior art midroller = 100% (reference), one can expect a crack propagation rate of 22% for the same track with the NPT as midroller. This is equivalent to a 4.5 x improvement in track life, from a first order theoretical perspective.

[0104] Exemplary midroller NPTs were constructed and tested using a track definition according to Table 1 and FIG. 17. A proprietary track system configuration was constructed that enabled midroller contact patch measurements, when loaded to various loads on the track inner periphery. Actual measured contact areas are provided in FIG. 25 for prior art and NPT midrollers for three different loads. The results are normalized, using the contact area of the prior art midroller at 100% design load as the reference.

[0105] The NPT midroller obtained about 50% greater contact area at the design load, and about 40% greater contact area at 133% of the design load. This was quite coherent with the FEA results, which predicted a 45% contact area increase at the reference load.

[0106] Using the proprietary track system, steady state track temperatures and track durability were measured. Proprietary conditions were employed, which the current applicant has determined correspond to accelerated track fatigue conditions. Normalized results are provided in Table 2:

[0107] Table 2

[0108] With an identical track, the track system with NPT MR heated up 18% over ambient test conditions. Further, internal cracks were detected in the system having prior art MR at 100% test duration, whereas no internal cracks were detected even after 400% test duration when using the NPT MR. Photos of track cross sections after testing are provided in FIG. 26 and 27 of the prior art midroller and NPT midroller respectively.

[0109] Therefore, in summary, an NPT midroller according to the invention was reduced to practice. Track thermal performance was markedly improved, with the rise in temperature being reduced by 18%. Track fatigue performance was improved by over a factor of 4.

[0110] In patent application US 63 / 507456 owned by the current applicant and included by reference herein, a high modulus insert 850 was disclosed for use within an annular beam of an NPT used in a track system. The same concept may be employed for aspects of the current invention, as shown in FIG. 28.

[0111] A high modulus insert may enable the elastomeric body to run cooler and / or enable a lower modulus elastomer to be used while supporting the same load. The high modulus insert may be thermoplastic with glass or carbon fiber reinforcement.

[0112] Furthermore, as shown in FIG. 28, the NPT may comprise a spoke structure which develops tension forces. This spoke structure may be used in place of the apertures previously disclosed.

[0113] FIG. 29 shows a thermoplastic rim 900 that may be used in accordance with aspects of the current invention. Instead of a metallic rim like that shown in FIG. 11 , a rim formed by thermoplastic injection may be light weight and may comprise complex geometries. These complex geometries may aid bonding with the elastomeric body and may be used in weight reduction. For example, in the embodiment shown, the rim 900 possesses numerous protrusions 970 on the radially outward flange 920.

Claims

I claim:1 . A non-pneumatic tire for use as a midroller in a track system, the non-pneumatic tire comprising: a rotational axis extending in an axial direction from a first axial extent to a second axial extent; a rim, an elastomeric portion partially encapsulating the rim; wherein the elastomeric portion further comprises a plurality of apertures disposed radially outward from the rim, the plurality of apertures extending in the axial direction.

2. The non-pneumatic tire of claim 1 wherein the rim has a first radially inward flange extending in a plane perpendicular to the rotational axis.

3. The non-pneumatic tire of claim 2 wherein the rim has a second radially outward flange extending in the direction parallel to the rotational axis.

4. The nonpneumatic tire of claim 3 wherein the plurality of apertures are positioned within the radially outward flange.

5. The nonpneumatic tire any one of claim 2 to claim 4 wherein the rim further comprises a plurality of mounting apertures for mounting to a vehicle.

6. The nonpneumatic tire of claim 5 wherein the mounting apertures are not encapsulated by the elastomeric portion.

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