Motorcycle tires

Abstract

To provide a tire for a two-wheeled vehicle achieving excellent handling performance.SOLUTION: A tire 2 for a two-wheeled vehicle comprises a pair of beads 10 and a carcass 12 laid across the beads 10. The carcass 12 comprises a first ply 12a provided with a plurality of first cords 36 arranged in parallel and a second ply 12b provided with a plurality of second cords 40 laminated outside the first ply 12a and arranged in parallel. The first cords 36 are inclined with respect to an equatorial plane CL, and an angle θ1 formed by the first cords 36 with respect to the equatorial plane CL is substantially 90°. The second cords 40 are inclined with respect to the equatorial plane CL, and an angle θ2 formed by the second cords 40 with respect to the equatorial plane CL is 65° or more and 85° or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present specification discloses a tire for a two-wheeled vehicle. [Background technology]

[0002] When a motorcycle is turning, the rider leans the motorcycle to obtain sufficient camber thrust. Tires for motorcycles are required to have excellent cornering stability, allowing the motorcycle to travel stably in this leaning state. When a motorcycle is traveling straight, it is nearly upright. Straight-line stability is also required for motorcycles. A study on a tire that achieves these requirements and has improved handling stability is disclosed in JP 2008-302871 A. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-302871 A Summary of the Invention [Problem to be solved by the invention]

[0004] As the performance of motorcycles improves, tires are required to have improved handling performance, enabling stable and smooth transitions between straight-ahead driving and cornering.

[0005] The present inventors have an intention to provide a tire for a two-wheeled vehicle that realizes excellent handling performance. [Means for solving the problem]

[0006] A preferred motorcycle tire includes a pair of beads and a carcass spanning the beads. The carcass includes a first ply having a plurality of first cords arranged in parallel, and a second ply having a plurality of second cords arranged in parallel and laminated on the outside of the first ply. The first cords are inclined with respect to the equatorial plane, and an angle θ1 formed by the first cord with respect to the equatorial plane is substantially 90°. The second cords are inclined with respect to the equatorial plane, and an angle θ2 formed by the second cord with respect to the equatorial plane is 65° or more and 85° or less. [Effects of the Invention]

[0007] In this motorcycle tire, in the carcass, the angle that the first cords of the first ply form with respect to the equatorial plane is substantially 90°, and the angle that the first cords of the second ply form with respect to the equatorial plane is 65° or more and 85° or less. This combination of the first ply and the second ply effectively contributes to good handling performance. This tire achieves excellent handling performance. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a portion of a pneumatic tire according to one embodiment. [Figure 2] FIG. 2 is a cutaway cross-sectional view of a portion of the tire of FIG. [Figure 3] 3 is a cross-sectional perspective view showing an enlarged view of the carcass of the tire of FIG. 1; FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a rubber sheet for forming the first ply of the carcass. [Figure 5] 5(A), (B), and (C) are graphs showing the evaluation results of the vertical spring constant of the tire. [Figure 6] 6(A), (B), and (C) are graphs showing the evaluation results of the amount of tire deflection. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, preferred embodiments will be described in detail with reference to the drawings as appropriate.

[0010] Fig. 1 shows a pneumatic tire 2. In Fig. 1, the up-down direction is the radial direction of the tire 2, the left-right direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. In Fig. 1, a dashed dotted line CL represents the equatorial plane of the tire 2. The shape of this tire 2 is symmetrical with respect to the equatorial plane CL, except for the tread pattern.

[0011] The tire 2 includes a tread 4, a pair of sidewalls 6, a pair of wings 8, a pair of beads 10, a carcass 12, a band 14, an inner liner 16, and a pair of chafers 18. The tire 2 is a tubeless type. The tire 2 is for a motorcycle. The tire 2 is mounted on the front wheel of the motorcycle.

[0012] Fig. 2 is a cutaway cross-sectional view showing a portion of the tire 2 in Fig. 1. Fig. 2 shows a state in which a portion of the tread 4 has been peeled away, exposing the carcass 12 and the band 14. As will be described later, the carcass 12 and the band 14 each include cords. In Fig. 2, these cords are exposed.

[0013] The tread 4 has a shape that is convex outward in the radial direction. The outer surface of the tread 4 that may come into contact with the road surface is called the tread surface 20. As shown in FIG. 2, grooves 22 are formed in the tread surface 20. These grooves 22 form a tread pattern. The tire 2 may be a slick tire in which the grooves 22 are not formed in the tread surface 20. The tread 4 is made of crosslinked rubber that has excellent wear resistance, heat resistance, and grip properties.

[0014] Each sidewall 6 extends radially inward from the vicinity of an end of the tread 4. The sidewalls 6 are made of crosslinked rubber that has excellent cut resistance and weather resistance. The sidewalls 6 prevent damage to the carcass 12.

[0015] Each wing 8 is located between the tread 4 and the sidewall 6. The wing 8 is bonded to each of the tread 4 and the sidewall 6. The wing 8 is made of crosslinked rubber with excellent adhesive properties.

[0016] Each bead 10 is located radially inward of the sidewall 6. The bead 10 includes a core 24 and an apex 26. The core 24 is ring-shaped and includes a wound inelastic wire. The wire is typically made of steel. The apex 26 extends radially outward from the core 24. The apex 26 tapers radially outward. The apex 26 is made of high-hardness crosslinked rubber.

[0017] As shown in Figures 1 and 2, the carcass 12 includes a first ply 12a and a second ply 12b. The second ply 12b is laminated on the outside of the first ply 12a on the inside of the tread 4. As shown in Figure 1, the first ply 12a and the second ply 12b are respectively laid between the beads 10 on both sides. The first ply 12a and the second ply 12b extend along the tread 4 and the sidewall 6.

[0018] As shown in FIG. 1 , the first ply 12a is folded back around the core 24 from the inside to the outside in the axial direction. As a result of this folding, the first ply 12a has a main portion 28 and a turned-up portion 30. The second ply 12b is folded back around the core 24 from the inside to the outside in the axial direction. As a result of this folding, the second ply 12b has a main portion 32 and a turned-up portion 34. The main portion 32 of the second ply 12b is layered on the outside of the main portion 28 of the first ply 12a. The second ply 12b does not have to be folded back around the core 24. The carcass 12 may be made up of three or more plies.

[0019] As shown in Figures 1 and 2, the band 14 is located radially inward of the tread 4. The band 14 is layered radially outward of the carcass 12. The band 14 is made of cords and a topping rubber. The cords are wound spirally. The band 14 has a so-called jointless structure. The cords extend substantially in the circumferential direction. The angle of the cords with respect to the circumferential direction is 5° or less, and even 2° or less. The cords are made of organic fibers. Preferred examples of organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0020] The inner liner 16 is located inside the carcass 12. The inner liner 16 is bonded to the inner surface of the carcass 12. The inner liner 16 is made of crosslinked rubber with excellent air barrier properties. A typical base rubber for the inner liner 16 is butyl rubber or halogenated butyl rubber. The inner liner 16 maintains the internal pressure of the tire 2.

[0021] Each chafer 18 is located near the bead 10. When the tire 2 is mounted on a rim, the chafer 18 comes into contact with the rim. This contact protects the area near the bead 10. In this embodiment, the chafer 18 is made of cloth and rubber impregnated into the cloth. The chafer 18 may also be made of crosslinked rubber.

[0022] 3 shows an enlarged view of a portion of the first ply 12a and the second ply 12b. In this view, for ease of understanding, the first ply 12a and the second ply 12b are shown spaced apart. In reality, the first ply 12a and the second ply 12b are in contact with each other, as shown in FIG. 1. In FIG. 3, arrow x represents the circumferential direction of the tire 2, arrow y represents the axial direction of the tire 2, and arrow z represents the radial direction of the tire 2.

[0023] As shown in FIG. 3, the first ply 12a is made up of a large number of parallel-arranged first cords 36 and a topping rubber 38. The first cords 36 are spaced apart from each other. A topping rubber 38 is present between each adjacent first cord 36. Each first cord 36 is inclined with respect to the equatorial plane CL. In FIG. 3, a double-headed arrow θ1 indicates the angle that the first cord 36 makes with respect to the equatorial plane CL. The angle θ1 is substantially 90°. Specifically, the angle θ1 is equal to or greater than 87° and equal to or less than 90°. The first cords 36 are made of organic fibers. Preferred examples of the organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, aramid fibers, and polyketone fibers.

[0024] Note that when the angle θ1 is deviated from 90°, the angle θ1 is measured at an acute angle between the equatorial plane CL and the first cord 36. In this case, the value of the angle θ1 is considered to be a positive value even if the first cord 36 is inclined toward either outer side in the axial direction as it moves toward one side in the circumferential direction of the tire 2. In other words, the angle θ1 is the absolute value of the angle between the equatorial plane CL and the first cord 36.

[0025] As shown in FIG. 3, the second ply 12b is made up of a large number of parallel-arranged second cords 40 and a topping rubber 42. The second cords 40 are spaced apart from each other. A topping rubber 42 is present between each adjacent second cord 40. Each second cord 40 is inclined with respect to the equatorial plane CL. In FIG. 3, a double-headed arrow θ2 indicates the angle that the second cord 40 makes with respect to the equatorial plane CL. The angle θ2 is 65° or greater and 85° or less. The second cords 40 are made of organic fibers. Preferred examples of the organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, aramid fibers, and polyketone fibers.

[0026] The angle θ2 is measured at an acute angle between the equatorial plane CL and the second cord 40. The value of the angle θ2 is a positive value even if the second cord 40 is inclined toward either outer side in the axial direction as it moves toward one side in the circumferential direction of the tire 2. In other words, the angle θ2 is the absolute value of the angle between the equatorial plane CL and the second cord 40.

[0027] In manufacturing the tire 2, a long first rubber sheet 44 for the first ply 12a and a long second rubber sheet for the second ply 12b are prepared. FIG. 4 is a cross-sectional view showing the first rubber sheet 44. The first rubber sheet 44 includes a plurality of first cords 36 arranged in parallel and a topping rubber 38. Each of the first cords 36 is generally covered with the topping rubber 38. The first cords 36 are inclined at substantially 90° with respect to the longitudinal direction of the first rubber sheet 44. FIG. 4 shows a cross section perpendicular to the direction in which the first cords 36 extend. In other words, FIG. 4 is a cross-sectional view taken along the longitudinal direction of the first rubber sheet 44.

[0028] 4, a double-headed arrow T1 indicates the thickness of the first rubber sheet 44, and a double-headed arrow P1 indicates the pitch of the first cords 36. The thickness T1 is preferably 0.5 mm or more and 2.0 mm or less. The pitch P1 is preferably 0.8 mm or more and 2.0 mm or less.

[0029] Although not shown, the second rubber sheet includes a plurality of parallel second cords 40 and a topping rubber 42. Each second cord 40 is generally covered with the topping rubber 42. The second cords 40 are inclined at an angle of 65° to 85° with respect to the longitudinal direction of the second rubber sheet.

[0030] The thickness T2 of the second rubber sheet is preferably 0.5 mm or greater and 2.0 mm or less. The pitch P2 of the second cord 40 is preferably 0.8 mm or greater and 2.0 mm or less.

[0031] In manufacturing this tire 2, the first rubber sheet 44 is wound around the drum of the molding device. The first rubber sheet 44 is wound around the outer periphery of the drum so that the longitudinal direction of the first rubber sheet 44 is the circumferential direction of the drum. The angle between the extension direction of the first cord 36 and the circumferential direction of the drum is substantially 90°. The second rubber sheet is wound around the outside of this first rubber sheet 44. The second rubber sheet is wound around the outside of the first rubber sheet 44 so that the longitudinal direction of the second rubber sheet is the circumferential direction of the drum. The angle between the extension direction of the second cord 40 and the circumferential direction of the drum is 65° or more and 85° or less.

[0032] Before winding the first rubber sheet 44 around the drum, sheets for forming other components of the tire 2 may be wound around the drum. For example, before winding the first rubber sheet 44 around the drum, a sheet for an inner liner may be wound around the drum. In this case, the first rubber sheet 44 is wound on the outside of the sheet for the inner liner.

[0033] The first rubber sheet 44 and the second rubber sheet are assembled with multiple other rubber components to obtain a raw cover (unvulcanized tire). This raw cover is placed in a mold. The raw cover is pressurized within the mold. This pressurization causes the raw cover to deform. This deformation is called shaping. The raw cover is further pressurized and heated within the mold. The pressure and heat cause the rubber composition of the raw cover to flow. The heat causes a crosslinking reaction in the rubber, resulting in the tire 2. The first ply 12a is formed from the first rubber sheet 44. The second ply 12b is formed from the second rubber sheet.

[0034] The shaping causes the first cord 36 and the second cord 40 to stretch. From the viewpoint of achieving sufficient stretch, the first cord 36 is preferably a twisted wire of organic fibers. The first cord 36 is preferably formed by twisting two or three yarns. From the same viewpoint, the second cord 40 is preferably a twisted wire of organic fibers. The second cord 40 is preferably formed by twisting two or three yarns. In each cord, the fineness of each yarn is preferably 500 dtex or more and 1000 dtex or less.

[0035] The effects of this embodiment will be described below.

[0036] In this motorcycle tire 2, the carcass 12 includes a first ply 12a and a second ply 12b layered on the outside of the first ply 12a. In the first ply 12a, the angle θ1 formed by the first cord 36 with the equatorial plane CL is substantially 90°. By setting the angle θ1 to 90°, the torsional force applied to the first ply 12a can be reduced, and the shear stress between the first ply 12a and the second ply 12b can be reduced. Furthermore, in the first cord 36 with an angle θ1 of 90°, the cord angle is less likely to change during the vulcanization process during manufacturing. An appropriate spacing between the first cords 36 is maintained. Furthermore, in this tire 2, the angle θ2 formed by the second cord 40 of the second ply 12b with the equatorial plane CL is 65° or more and 85° or less. By layering the second ply 12b on the outside of the first ply 12a, an excellent hoop effect is achieved. As a result, the tire 2 achieves appropriate deflection while suppressing the vertical spring constant. These effectively improve the handling performance. Tire 2 achieves excellent handling performance.

[0037] The small vertical spring constant and moderate deflection effectively contribute to cornering performance, and the tire 2 achieves excellent cornering performance.

[0038] In this tire 2, the second ply 12b is located on the inner side of the tread 4, outward of the first ply 12a. The second ply 12b is closer to the tread surface 20 than the first ply 12a. In the second ply 12b, the angle θ2 formed by the second cord 40 with the equatorial plane CL is 65° or greater and 85° or less. In this tire 2, the second cord 40 is inclined toward one outer side in the axial direction (to the right or left with respect to the traveling direction) as it approaches the traveling direction of the tire 2. Since the second cord 40 closer to the tread surface 20 is inclined, this second cord 40 facilitates turning in the inclined direction of the second cord 40. Furthermore, the first cord 36 is farther from the tread surface 20 than the second cord 40, and the angle θ1 is substantially 90°. This first cord 36 is less likely to interfere with turning performance in the inclined direction of the second cord 40. In this tire 2, turning performance in the inclined direction of the second cord 40 is further improved. For example, when running on a circuit course with many right-turning corners, by employing the second ply 12b in which the second cords 40 are inclined to the right, it is possible to complete a circuit of the course in a shorter lap.

[0039] From the standpoint of achieving excellent handling performance and cornering performance, the angle θ2 is more preferably equal to or greater than 70°, and further preferably equal to or greater than 72°. From this standpoint, the angle θ2 is more preferably equal to or less than 80°, and further preferably equal to or less than 78°.

[0040] Although not shown, angle θ3 represents the angle between the first cord 36 and the second cord 40. From the viewpoint of achieving excellent handling performance and cornering performance, angle θ3 is preferably equal to or greater than 5°, more preferably equal to or greater than 10°, and even more preferably equal to or greater than 12°. From this viewpoint, angle θ3 is preferably equal to or less than 25°, more preferably equal to or less than 20°, and even more preferably equal to or less than 18°.

[0041] The angle θ3 is measured at an acute angle between the first cord 36 and the second cord 40. The value of the angle θ3 is a positive value even if the second cord 40 is inclined toward either outer side in the axial direction as it moves toward one side in the circumferential direction of the tire 2. In other words, the angle θ3 is the absolute value of the angle between the first cord 36 and the second cord 40.

[0042] As described above, the second ply 12b is preferably folded back around the bead 10. The turned-up portion 34 of the second ply 12b contributes to appropriate rigidity of the side portion of the tire 2. Furthermore, at the position where the main portion 32 and the turned-up portion 34 of the second ply 12b overlap, the inclination direction of the second cords 40 in the main portion 32 is opposite to the inclination direction of the second cords 40 in the turned-up portion 34. Because the second cords 40 with opposite inclination directions overlap, appropriate rigidity is achieved against forces from multiple directions. This, together with setting the inclination angles θ1 and θ2 within the above-mentioned ranges, contributes to the realization of excellent handling performance and cornering ability.

[0043] As described above, the first ply 12a is preferably folded back around the bead 10. The folded back portion 30 of the first ply 12a contributes to appropriate rigidity of the side portion of the tire 2. This, together with setting the inclination angles θ1 and θ2 within the above-mentioned ranges, contributes to realizing excellent handling performance and cornering ability.

[0044] As described above, the second cords 40 having opposite inclination directions overlap with each other at the overlapping portion of the main portion 32 and the folded-back portion 34 of the second ply 12b. Since the inclination angle θ2 of the second cords 40 is 65° or more and 85° or less, the angle θ4 formed by the second cords 40 having opposite inclination directions is 10° or more and 50° or less. From the viewpoint of realizing excellent handling performance and cornering performance, the difference (θ4 - θ3) between the angle θ4 and the angle θ3 is preferably 5° or more, more preferably 10° or more, and even more preferably 12° or more. From this viewpoint, the difference (θ4 - θ3) is preferably 25° or less, more preferably 20° or less, and even more preferably 18° or less.

[0045] As shown in Fig. 1, it is preferable that the outer ends of the turn-up portions 30 of the first ply 12a and the outer ends of the turn-up portions 34 of the second ply 12b are both located radially inward from the edge of the tread surface 20. In this way, the turn-up portions 30 of the first ply 12a and the turn-up portions 34 of the second ply 12b are less likely to interfere with turning performance in the direction in which the second cords 40 are inclined. In this tire 2, turning performance in the direction in which the second cords 40 are inclined is further improved. In this tire 2, excellent turning performance is achieved while achieving appropriate rigidity in the side portions.

[0046] In FIG. 1, the double-headed arrow D1 indicates the radial distance between the edge of the tread surface 20 and the outer edge of the turned-up portion 30 of the first ply 12a. The distance D1 is preferably 5 mm or more. By setting the distance D1 to 5 mm or more, the turned-up portion 30 of the first ply 12a is less likely to interfere with cornering performance. From this perspective, the distance D1 is more preferably 8 mm or more, and even more preferably 10 mm or more. The distance D1 is preferably 25 mm or less. By setting the distance D1 to 25 mm or less, the turned-up portion 30 of the first ply 12a contributes to appropriate rigidity of the side portions. From this perspective, the distance D1 is more preferably 22 mm or less, and even more preferably 20 mm or less.

[0047] In FIG. 1, the double-headed arrow D2 indicates the radial distance between the edge of the tread surface 20 and the outer edge of the turned-up portion 34 of the second ply 12b. The distance D2 is preferably 1 mm or more. By setting the distance D2 to 1 mm or more, the turned-up portion 34 of the second ply 12b is less likely to interfere with cornering performance. From this perspective, the distance D2 is more preferably 3 mm or more, and even more preferably 5 mm or more. The distance D2 is preferably 15 mm or less. By setting the distance D2 to 15 mm or less, the turned-up portion 34 of the second ply 12b contributes to appropriate rigidity of the side portion. From this perspective, the distance D2 is more preferably 12 mm or less, and even more preferably 10 mm or less.

[0048] As shown in FIG. 1 , the outer end of the turn-up portion 34 of the second ply 12b is preferably located radially outward of the outer end of the turn-up portion 30 of the first ply 12a. Because the turn-up portion 34 of the second ply 12b is located more inward of the tire 2 than the turn-up portion 30 of the first ply 12a, extending the turn-up portion 34 of the second ply 12b radially outward does not impede cornering performance. On the other hand, extending the turn-up portion 34 of the second ply 12b radially outward can increase the width of the overlapping portion between the main portion 32 and the turn-up portion 34 of the second ply 12b. The overlapping portion of the second cords 40, which are inclined in the opposite direction, is lengthened, thereby more effectively achieving appropriate rigidity against forces from multiple directions.

[0049] In Figure 1, the double-headed arrow L represents the radial distance between the outer end of the turned-up portion 30 of the first ply 12a and the outer end of the turned-up portion 34 of the second ply 12b. From the viewpoint of achieving good turning performance and appropriate rigidity, the distance L is preferably 1 mm or more, more preferably 3 mm or more, and even more preferably 5 mm or more. From this viewpoint, the distance L is preferably 15 mm or less, more preferably 12 mm or less, and even more preferably 10 mm or less.

[0050] In FIG. 1, the straight line BBL represents the bead baseline of the tire 2. The double-headed arrow H represents the section height of the tire. The section height H is the radial height of the tire measured from the bead baseline BBL at the equator. The double-headed arrow HP1 represents the radial height of the turnup portion 30 of the first ply 12a measured from the bead baseline BBL. The double-headed arrow HP2 represents the radial height of the turnup portion 34 of the second ply 12b measured from the bead baseline BBL.

[0051] The ratio (HP1 / H) of the height HP1 to the cross-sectional height H is preferably 0.10 or greater. By setting the ratio (HP1 / H) to 0.10 or greater, the turned-up portion 30 of the first ply 12a contributes to appropriate rigidity of the side portion. From this viewpoint, the ratio (HP1 / H) is more preferably 0.15 or greater, and even more preferably 0.20 or greater. The ratio (HP1 / H) is preferably 0.35 or less. By setting the ratio (HP1 / H) to 0.35 or less, the turned-up portion 30 of the first ply 12a is less likely to interfere with cornering performance. From this viewpoint, the ratio (HP1 / H) is more preferably 0.30 or less, and even more preferably 0.25 or less.

[0052] The ratio (HP2 / H) of the height HP2 to the cross-sectional height H is preferably 0.15 or greater. By setting the ratio (HP2 / H) to 0.15 or greater, the turned-up portion 34 of the second ply 12b contributes to appropriate rigidity of the side portion. From this viewpoint, the ratio (HP2 / H) is more preferably 0.20 or greater, and even more preferably 0.25 or greater. The ratio (HP2 / H) is preferably 0.40 or less. By setting the ratio (HP2 / H) to 0.40 or less, the turned-up portion 34 of the second ply 12b is less likely to interfere with cornering performance. From this viewpoint, the ratio (HP2 / H) is more preferably 0.35 or less, and even more preferably 0.30 or less.

[0053] The dimensions and angles of each component of the tire 2 are measured when the tire 2 is mounted on a standard rim and inflated to the standard internal pressure. No load is applied to the tire 2 during measurement. In this specification, the standard rim refers to the rim specified in the standard on which the tire 2 is based. The "standard rim" in the JATMA standard, the "design rim" in the TRA standard, and the "measuring rim" in the ETRTO standard are standard rims. In this specification, the standard internal pressure refers to the internal pressure specified in the standard on which the tire 2 is based. The "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AS VARIOUS COLD INFLATION PRESSURE" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are standard internal pressures. [Example]

[0054] The effects of the motorcycle tires according to the examples will be explained below, but the scope of the present specification should not be construed as being limited based on the description of these examples.

[0055] [Example 1] A motorcycle tire of Example 1 was obtained having the structure shown in Figure 1. The tire size was 120 / 70R17. The angles θ1 and θ2 of this tire are shown in Table 1.

[0056] [Comparative Examples 1-5, Examples 2-5] Tires of Comparative Examples 1-5 and Examples 2-5 were obtained in the same manner as in Example 1, except that the angles θ1 and θ2 were set as shown in Tables 1 and 2.

[0057] [Vertical spring constant measurement] The vertical spring constants of the tires of Example 1 and Comparative Examples 1 to 3 were measured under the following conditions. Rim size: MT3.50 x 17 Internal pressure: 230kPa Load T: 0.54kN, 1.1kN, 1.6kN Camber angle Ca: 0~50° FIG. 5 shows the results of measuring the vertical spring constant when the camber angle Ca was changed from 0° to 50°. FIG. 5(A) shows the results when the load T was 0.54 kN, FIG. 5(B) shows the results when the load T was 1.1 kN, and FIG. 5(C) shows the results when the load T was 1.6 kN. Table 1 also shows the results when the load T was 0.54 kN and the camber angle Ca was 20°, expressed as an index with Comparative Example 1 set to 100. The smaller the vertical spring constant, the better the handling and cornering performance. The smaller the vertical spring constant, the more preferable it is. Note that the scales of the vertical axes in FIGS. 5(A), 5(B), and 5(C) are not the same. Therefore, for example, FIGS. 5(a) and 5(b) cannot be compared. These are intended to compare Example 1 and Comparative Examples 1-3 within each graph.

[0058] [Deflection measurement] The amount of deflection was measured under the following conditions for the tires of Example 1 and Comparative Examples 1 to 3. The amount of deflection was calculated as the difference between the section height of the tire when no load was applied and the section height of the tire when a load was applied. Rim size: MT3.50 x 17 Internal pressure: 230kPa Load T: 0.54kN, 1.1kN, 1.6kN Camber angle Ca: 0~50° FIG. 6 shows the measurement results of the deflection amount when the camber angle Ca was changed from 0° to 50°. FIG. 6(A) shows the results when the load T was 0.54 kN, FIG. 6(B) shows the results when the load T was 1.1 kN, and FIG. 6(C) shows the results when the load T was 1.6 kN. Table 1 also shows the results when the load T was 0.54 kN and the camber angle Ca was 20°, expressed as an index with Comparative Example 1 set to 100. The larger the deflection amount, the better the handling and cornering performance. The larger the deflection amount, the more preferable it is. Note that the vertical axis scales in FIGS. 6(A), 6(B), and 6(C) are not the same. Therefore, for example, FIG. 6(A) and FIG. 6(B) cannot be compared. These are intended to compare Example 1 and Comparative Examples 1-3 within each graph.

[0059] [Handling performance] The above tire was mounted on a standard rim (rim size = MT3.50 x 17) and mounted on the front wheel of a motorcycle with an engine displacement of 1000cc. Air was inflated to an internal pressure of 200 kPa. A conventional tire was mounted on the rear wheel of the motorcycle. The motorcycle was run on a circuit course, and a sensory evaluation was conducted by the rider. The evaluation item was handling performance. The results are shown in Table 1-2 on a four-point scale of A, B, C, and D. A, B, C, and D indicate better handling performance, respectively. A, B, C, and D are more preferable.

[0060] [Table 1]

[0061] [Table 2]

[0062] As shown in Figures 5-6 and Table 1-2, the tires of the examples are superior in handling performance to the tires of the comparative examples. These evaluation results clearly demonstrate the superiority of the present motorcycle tires.

[0063] [Disclosure items] The following items are disclosures of preferred embodiments.

[0064] [Item 1] The tire has a pair of beads and a carcass that is laid across the beads, the carcass includes a first ply having a plurality of first cords arranged in parallel, and a second ply laminated on an outer side of the first ply and having a plurality of second cords arranged in parallel, the first cord is inclined with respect to the equatorial plane, and an angle θ1 formed by the first cord with respect to the equatorial plane is substantially 90°, The tire for a two-wheeled vehicle, wherein the second cord is inclined with respect to the equatorial plane, and an angle θ2 formed by the second cord with respect to the equatorial plane is equal to or greater than 65° and equal to or less than 85°.

[0065] [Item 2] 2. The motorcycle tire according to claim 1, wherein the angle θ2 is equal to or greater than 70° and equal to or less than 80°.

[0066] [Item 3] 3. The motorcycle tire according to claim 1, wherein the second ply is turned up around the bead to form a turned-up portion.

[0067] [Item 4] 4. The motorcycle tire according to item 3, wherein the first ply is turned up around the bead, thereby forming a turned-up portion.

[0068] [Item 5] The tire further comprises a tread having a tread surface that contacts the road surface, 5. The motorcycle tire according to Item 4, wherein an outer end of the turned-up portion of the first ply and an outer end of the turned-up portion of the second ply are both located radially inward of an edge of the tread surface.

[0069] [Item 6] 6. The motorcycle tire according to item 4 or 5, wherein an outer end of the turned-up portion of the second ply is positioned radially outward from an outer end of the turned-up portion of the first ply.

[0070] [Item 7] 7. A two-wheeled vehicle tire according to any one of items 4 to 6, wherein, in the radial direction, a ratio of a height of a turned-up portion of the first ply to a section height of the tire is 0.10 or more and 0.35 or less, and a ratio of a height of a turned-up portion of the second ply to a section height of the tire is 0.15 or more and 0.40 or less. [Industrial Applicability]

[0071] The tire described above can also be applied to various two-wheeled vehicles. [Explanation of symbols]

[0072] 2. Tires 4. Tread 6. Sidewall 8···Wing 10 Bead 12. Carcass 12a···First Ply 12b Second ply 14...Band 16···Inner liner 18. Chafer 20 Tread surface 22...Groove 24 cores 26 Apex 28, 32... Main part 30, 34... Folded part 36...First Code 38, 42... Topping rubber 40...Second code 44···First rubber sheet

Claims

1. A tire comprising a pair of beads and a carcass stretched across the beads, the carcass includes a first ply having a plurality of first cords arranged in parallel, and a second ply laminated on an outer side of the first ply and having a plurality of second cords arranged in parallel, the first cord is inclined with respect to an equatorial plane, and an angle θ1 formed by the first cord with respect to the equatorial plane is substantially 90°, the second cord is inclined with respect to the equatorial plane, and an angle θ2 formed by the second cord with respect to the equatorial plane is equal to or greater than 65° and is equal to or less than 85°, the second ply is turned up around the bead to form a turned-up portion; the first ply is turned up around the bead to form a turned-up portion; The tire further comprises a tread having a tread surface that contacts the road surface, In a tire for a two-wheeled vehicle, an outer end of a turned-up portion of the first ply and an outer end of a turned-up portion of the second ply are both located radially inward of an edge of the tread surface.

2. A tire comprising a pair of beads and a carcass stretched across the beads, the carcass includes a first ply having a plurality of first cords arranged in parallel, and a second ply laminated on an outer side of the first ply and having a plurality of second cords arranged in parallel, the first cord is inclined with respect to an equatorial plane, and an angle θ1 formed by the first cord with respect to the equatorial plane is substantially 90°, the second cord is inclined with respect to the equatorial plane, and an angle θ2 formed by the second cord with respect to the equatorial plane is equal to or greater than 65° and is equal to or less than 85°, the second ply is turned up around the bead to form a turned-up portion; the first ply is turned up around the bead to form a turned-up portion; a tire for a two-wheeled vehicle, wherein an outer end of the turned-up portion of the second ply is positioned radially outward from an outer end of the turned-up portion of the first ply.

3. A tire comprising a pair of beads and a carcass stretched across the beads, the carcass includes a first ply having a plurality of first cords arranged in parallel, and a second ply laminated on an outer side of the first ply and having a plurality of second cords arranged in parallel, the first cord is inclined with respect to an equatorial plane, and an angle θ1 formed by the first cord with respect to the equatorial plane is substantially 90°, the second cord is inclined with respect to the equatorial plane, and an angle θ2 formed by the second cord with respect to the equatorial plane is equal to or greater than 65° and is equal to or less than 85°, the second ply is turned up around the bead to form a turned-up portion; the first ply is turned up around the bead to form a turned-up portion; A tire for a two-wheeled vehicle, wherein, in the radial direction, a ratio of a height of a turned-up portion of the first ply to a cross-sectional height of the tire is 0.10 or more and 0.35 or less, and a ratio of a height of a turned-up portion of the second ply to a cross-sectional height of the tire is 0.15 or more and 0.40 or less.

4. The tire for a two-wheeled vehicle according to any one of claims 1 to 3, wherein the angle θ2 is equal to or greater than 70° and equal to or less than 80°.

Images