Motor vehicle tyre

Abstract

The motor vehicle tire (2) is equipped with a pair of beads (10) and a carcass (12) spanning the interval between said beads (10). The carcass (12) is equipped with a first ply (12a) provided with a plurality of first cords (36) arranged parallel to each other and a second ply (12b) laminated to the outside of the first ply (12a) and provided with a plurality of second cords (40) arranged parallel to each other. The first cords (36) are inclined with respect to the equatorial plane (CL) and form an angle (θ1) with respect to the equatorial plane (CL) substantially equal to 90°. The second cords (40) are inclined with respect to the equatorial plane (CL) and form an angle (θ2) with respect to the equatorial plane (CL) substantially equal to 65°-85°, including 65° and 85°.

Description

Technical Field

[0001] This invention relates to tires for two-wheeled motor vehicles. Background Technology

[0002] When a two-wheeled vehicle turns, the rider leans the vehicle to obtain sufficient camber thrust. This requires the tires of the two-wheeled vehicle to have excellent cornering stability to achieve stable driving while leaning. During straight-line travel, the two-wheeled vehicle is almost upright. Stability during straight-line travel is also required. Japanese Patent Application Publication No. 2008-302871 discloses research on tires that achieve excellent cornering and straight-line stability, as well as improved handling stability.

[0003] Reference List

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-302871 (Pending Examination) Summary of the Invention

[0006] Technical issues

[0007] Although the performance of two-wheeled vehicles has been enhanced, there is a need for tires with improved handling that enable a stable and smooth transition between straight driving and cornering.

[0008] The inventors of this invention aim to provide a tire for two-wheeled motor vehicles that achieves excellent handling performance.

[0009] Solution to the problem

[0010] A preferred tire for a two-wheeled motor vehicle includes: a pair of bead rings; and a tire carcass extending over and between the bead rings. The tire carcass includes: a first ply comprising a plurality of first cords arranged in parallel; and a second ply stacked on the outside of the first ply and comprising a plurality of second cords arranged in parallel. The first cords are inclined relative to the equatorial plane, and each first cord forms an angle θ1 relative to the equatorial plane, the angle θ1 being substantially 90°. The second cords are inclined relative to the equatorial plane, and each second cord forms an angle θ2 relative to the equatorial plane, the angle θ2 being greater than or equal to 65° and less than or equal to 85°.

[0011] Beneficial effects of the present invention

[0012] In the aforementioned tire for two-wheeled motor vehicles, in the tire carcass, each first cord of the first ply forms an angle of approximately 90° with respect to the equatorial plane, and each second cord of the second ply forms an angle of greater than or equal to 65° and less than or equal to 85° with respect to the equatorial plane. The combination of the first and second ply effectively contributes to favorable handling performance. This tire achieves excellent handling performance. Attached Figure Description

[0013] [ Figure 1 ] Figure 1 This is a cross-sectional view showing a portion of an inflatable tire according to one embodiment.

[0014] [ Figure 2 ] Figure 2 It is shown Figure 1 A cross-sectional view of a portion of a tire.

[0015] [ Figure 3 ] Figure 3 yes Figure 1 An enlarged 3D cross-sectional view of the tire carcass.

[0016] [ Figure 4 ] Figure 4 This is a cross-sectional view of the rubber sheet used to form the first ply of the tire carcass.

[0017] [ Figure 5 ] Figure 5 (A), (B), and (C) are graphs showing the evaluation results of the tire with respect to its vertical stiffness constant.

[0018] [ Figure 6 ] Figure 6 (A), (B), and (C) are graphs showing the evaluation results of the tires with respect to their deflection. Detailed Implementation

[0019] Preferred embodiments will be described in detail below with appropriate reference to the accompanying drawings.

[0020] Figure 1 A pneumatic tire 2 is shown. Figure 1 In the diagram, the vertical direction is the radial direction of tire 2; the horizontal direction is the axial direction of tire 2; and the perpendicular direction is... Figure 1 The direction of the plane is the circumferential direction of tire 2. Figure 1 In the diagram, the single-dot line CL represents the equatorial plane of tire 2. Apart from its tread pattern, the shape of tire 2 is symmetrical about the equatorial plane CL.

[0021] Tire 2 includes a tread 4, a pair of sidewalls 6, a pair of wings 8, a pair of bead 10, a carcass 12, a belt 14, an inner liner 16, and a pair of bead wraps 18. Tire 2 is a tubeless type. Tire 2 is used in two-wheeled motor vehicles. Tire 2 is mounted on the front wheel of a two-wheeled motor vehicle.

[0022] Figure 2 It is shown Figure 1 A cross-sectional view of a portion of tire 2. Figure 2 The diagram shows a state where a portion of the tread 4 has been peeled off, exposing the tire carcass 12 and belt 14. As described below, each of the tire carcass 12 and belt 14 comprises cords. Figure 2 In the middle, these cords are exposed.

[0023] The tread 4 has a radially outward protruding shape. The outer surface of the tread 4 that contacts the road surface is called the tread surface 20. For example... Figure 2 As shown, grooves 22 are formed in the tread surface 20. The grooves 22 form the tread pattern. The tire 2 can be a smooth tire without grooves 22 formed in the tread surface 20. The tread 4 is made of cross-linked rubber with excellent wear resistance, heat resistance and grip performance.

[0024] Each sidewall 6 extends substantially radially inward from near the end of the tread 4. The sidewall 6 is made of cross-linked rubber with excellent cut resistance and weather resistance. The sidewall 6 prevents damage to the carcass 12.

[0025] Each wing 8 is located between the tread 4 and the sidewall 6. The wing 8 is attached to each of the tread 4 and the sidewall 6. The wing 8 is made of cross-linked rubber with excellent adhesion.

[0026] Each bead 10 is located radially inside the sidewall 6. The bead 10 includes a core 24 and a triangular rubber 26. The core 24 is annular and includes a wound, non-stretchable thread. Typically, the thread is made of steel. The triangular rubber 26 extends radially outward from the core 24. The triangular rubber 26 tapers radially outward. The triangular rubber 26 is made of a cross-linked rubber with high hardness.

[0027] like Figure 1 and Figure 2 As shown, the tire carcass 12 includes a first ply 12a and a second ply 12b. On the inner side of the tread 4, the second ply 12b is layered over the outer side of the first ply 12a. Figure 1 As shown, each of the first ply 12a and the second ply 12b extends on and between the bead 10 on both sides. The first ply 12a and the second ply 12b extend along the tread 4 and the sidewall 6.

[0028] like Figure 1As shown, the first ply 12a is rolled up around each core 24 from the axially inward side to the axially outward side. Because the first ply 12a is rolled up in this manner, it includes a main portion 28 and a rolled-up portion 30. The second ply 12b is rolled up around each core 24 from the axially inward side to the axially outward side. Because the second ply 12b is rolled up in this manner, it includes a main portion 32 and a rolled-up portion 34. The main portion 32 of the second ply 12b overlaps the main portion 28 of the first ply 12a. The second ply 12b does not need to be rolled up around each core 24. The carcass 12 may include three or more ply layers.

[0029] like Figure 1 and Figure 2 As shown, belt 14 is located radially inside the tread 4. Belt 14 is stacked radially outside the carcass 12. Belt 14 comprises cords and a top layer of rubber. The cords are spirally wound. Belt 14 has a so-called seamless structure. The cords extend substantially in the circumferential direction. The angle of the cords relative to the circumferential direction is less than or equal to 5°, and more preferably less than or equal to 2°. Each cord is made of organic fibers. Preferred examples of organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0030] The inner liner 16 is located inside the tire carcass 12. The inner liner 16 is bonded to the inner surface of the tire carcass 12. The inner liner 16 is made of a cross-linked rubber with excellent airtightness. Typical base rubbers for the inner liner 16 are isobutylene-isoprene rubber or halogenated isobutylene-isoprene rubber. The inner liner 16 maintains the internal pressure of the tire 2.

[0031] Each bead wrap 18 is located near the bead 10. When the tire 2 is fitted into the rim, the bead wrap 18 abuts against the rim. By abutting, the vicinity of the bead 10 is protected. In this embodiment, the bead wrap 18 is made of cloth and rubber impregnated into the cloth. The bead wrap 18 may be made of cross-linked rubber.

[0032] Figure 3 An enlarged view of a portion of each of the first fabric layer 12a and the second fabric layer 12b is shown. Figure 3 For ease of understanding, the first fabric layer 12a and the second fabric layer 12b are shown, spaced apart from each other. In practice, as... Figure 1 As shown, the first fabric layer 12a and the second fabric layer 12b are in contact with each other. Figure 3 In the diagram, arrow x represents the circumferential direction of tire 2; arrow y represents the axial direction of tire 2; and arrow z represents the radial direction of tire 2.

[0033] like Figure 3As shown, the first ply 12a includes a large number of parallel first cords 36 and a top layer rubber 38. Each first cord 36 is spaced apart from its adjacent first cord 36. The top layer rubber 38 is present between each first cord 36 and its adjacent first cord 36. Each first cord 36 is inclined relative to the equatorial plane CL. Figure 3 In the diagram, the double-headed arrow θ1 represents the angle formed by each first cord 36 relative to the equatorial plane CL. Angle θ1 is substantially 90°. Specifically, angle θ1 is greater than or equal to 87° and less than or equal to 90°. Each first cord 36 is made of organic fibers. Preferred examples of organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, aramid fibers, and polyketone fibers.

[0034] It should be noted that when angle θ1 is not 90°, one of the acute angles formed by the equatorial plane CL and the first cord 36 is used as angle θ1 for measurement. In this case, in one circumferential direction of the tire 2, regardless of whether the first cord 36 is tilted towards one axially outward or the other axially outward, the value of angle θ1 is taken as positive. That is, angle θ1 is the absolute value of the angle formed by the equatorial plane CL and the first cord 36.

[0035] like Figure 3 As shown, the second ply 12b includes a large number of parallelly arranged second cords 40 and a top layer rubber 42. Each second cord 40 is spaced apart from its adjacent second cord 40. The top layer rubber 42 is present between each second cord 40 and its adjacent second cord 40. Each second cord 40 is inclined relative to the equatorial plane CL. Figure 3 In the diagram, the double-headed arrow θ2 represents the angle formed by each second cord 40 relative to the equatorial plane CL. Angle θ2 is greater than or equal to 65° and less than or equal to 85°. Each second cord 40 is made of organic fibers. Preferred examples of organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, aramid fibers, and polyketone fibers.

[0036] It should be noted that the acute angle formed by the equatorial plane CL and the second cord 40 is measured as angle θ2. In one circumferential direction of the tire 2, regardless of whether the second cord 40 is tilted outward in one axial direction or the other, the value of angle θ2 is taken as positive. That is, angle θ2 is the absolute value of the angle formed by the equatorial plane CL and the second cord 40.

[0037] In the production of tire 2, an elongated first rubber sheet 44 for the first ply 12a and an elongated second rubber sheet for the second ply 12b are prepared. Figure 4This is a cross-sectional view of the first rubber sheet 44. The first rubber sheet 44 includes a plurality of first cords 36 arranged in parallel and a top layer rubber 38. Each first cord 36 is typically covered by the top layer rubber 38. Each first cord 36 is substantially inclined at 90° relative to the longitudinal direction of the first rubber sheet 44. Figure 4 A cross-section perpendicular to the direction in which the first cord 36 extends is shown. In other words, Figure 4 It is a cross-sectional view of the first rubber sheet 44 taken along the longitudinal direction of the first rubber sheet 44.

[0038] exist Figure 4 In the diagram, the double-headed arrow T1 represents the thickness of the first rubber sheet 44, and the double-headed arrow P1 represents the spacing between the first cords 36. The thickness T1 is preferably greater than or equal to 0.5 mm and less than or equal to 2.0 mm. The spacing P1 is greater than or equal to 0.8 mm and less than or equal to 2.0 mm.

[0039] Although not shown, the second rubber sheet includes a plurality of second cords 40 arranged in parallel and a top layer rubber 42. Each second cord 40 is typically covered by the top layer rubber 42. Each second cord 40 is inclined at 65° to 85° relative to the longitudinal direction of the second rubber sheet.

[0040] Preferably, the second rubber sheet has a thickness T2 greater than or equal to 0.5 mm and less than or equal to 2.0 mm. Preferably, the spacing P2 between the second cords 40 is greater than or equal to 0.8 mm and less than or equal to 2.0 mm.

[0041] In the production of tire 2, a first rubber sheet 44 is wound onto the drum of the forming machine. The first rubber sheet 44 is wound around the outer periphery of the drum such that the longitudinal direction of the first rubber sheet 44 is the circumferential direction of the drum. The angle formed by the direction of extension of the first cord 36 and the circumferential direction of the drum is approximately 90°. A second rubber sheet is wound around the outside of the first rubber sheet 44. The second rubber sheet is wound around the outside of the first rubber sheet 44 such that the longitudinal direction of the second rubber sheet is the circumferential direction of the drum. The angle formed by the direction of extension of the second cord 40 and the circumferential direction of the drum is greater than or equal to 65° and less than or equal to 85°.

[0042] Before the first rubber sheet 44 is wound onto the drum, another sheet for forming another component of the tire 2 can be wound onto the drum. For example, a sheet for the inner liner can be wound onto the drum before the first rubber sheet 44 is wound onto the drum. In this case, the first rubber sheet 44 is wound on the outside of the sheet for the inner liner.

[0043] The first rubber sheet 44 and the second rubber sheet are assembled with several other rubber components to obtain a cover (uncured tire). The cover is placed in a mold. The cover is pressurized in the mold. The cover is deformed by the pressure. Deformation is called forming. The cover is further pressurized and heated in the mold. The pressure and heating cause the rubber composition of the cover to flow. Due to the heating, the rubber undergoes a cross-linking reaction, thereby obtaining tire 2. The first ply 12a is formed by the first rubber sheet 44. The second ply 12b is formed by the second rubber sheet.

[0044] This forming process results in the stretching of the first cord 36 and the second cord 40. From the viewpoint of achieving sufficient stretching, each first cord 36 is preferably an organic fiber strand. Each first cord 36 is preferably obtained by twisting two or three yarns together. From the same viewpoint, each second cord 40 is preferably an organic fiber strand. Each second cord 40 is preferably obtained by twisting two or three yarns together. In each cord, the fineness of each yarn is preferably greater than or equal to 500 dtex and less than or equal to 1000 dtex.

[0045] The functional advantages of this embodiment will be described below.

[0046] In a tire 2 for a two-wheeled motor vehicle, the tire carcass 12 includes a first ply 12a and a second ply 12b stacked on the outside of the first ply 12a. In the first ply 12a, each first cord 36 forms an angle θ1 with the equatorial plane CL that is substantially 90°. By setting the angle θ1 to 90°, the torsional force applied to the first ply 12a is reduced, and the shear stress between the first ply 12a and the second ply 12b is also reduced. With the angle θ1 of each first cord 36 at 90°, the cord angle hardly changes during the vulcanization step during production. Therefore, an appropriate distance is maintained between the first cords 36. Furthermore, in the tire 2, each second cord 40 of the second ply 12b forms an angle θ2 with the equatorial plane CL that is greater than or equal to 65° and less than or equal to 85°. Since the second ply 12b is stacked on the outside of the first ply 12a, excellent rimming effect is achieved. These characteristics allow for appropriate deflection of tire 2 while reducing its vertical stiffness constant. Therefore, handling performance is effectively improved. Tire 2 achieves excellent handling performance.

[0047] The reduced vertical stiffness constant and appropriate deflection effectively contribute to cornering performance. Tire 2 achieves excellent cornering performance.

[0048] On the inner side of the tread 4 of tire 2, the second ply 12b is located outside 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, each second cord 40 forms an angle θ2 with the equatorial plane CL greater than or equal to 65° and less than or equal to 85°. In tire 2, each second cord 40 is inclined axially outward (relative to the right or left of the direction of travel). Because the second cords 40 closer to the tread surface 20 are inclined, cornering can be easily performed in the direction in which the second cords 40 are inclined. Furthermore, the first cord 36 is positioned further away from the tread surface 20 than the second cords 40, and the angle θ1 is essentially 90°. During cornering in the direction in which the second cords 40 are inclined, the first cord 36 is less likely to hinder cornering performance. Tire 2 constructed in this way has improved cornering performance when cornering in the direction in which the second cords 40 are inclined. For example, in cases where a two-wheeled vehicle will be running on a loop route with many right angles, the use of a second cord layer 12b with the second cord 40 tilted to the right allows the two-wheeled vehicle to run on the loop route with a shorter overlap time.

[0049] From the viewpoint of achieving excellent handling and cornering performance, angle θ2 is more preferably greater than or equal to 70°, and even more preferably greater than or equal to 72°. From the same viewpoint, angle θ2 is more preferably less than or equal to 80°, and even more preferably less than or equal to 78°.

[0050] Although not shown, an angle θ3 exists, which is the angle formed by each first cord 36 and each second cord 40. From the viewpoint of achieving excellent handling and cornering performance, angle θ3 is preferably greater than or equal to 5°, more preferably greater than or equal to 10°, and even more preferably greater than or equal to 12°. From the same viewpoint, angle θ3 is preferably less than or equal to 25°, more preferably less than or equal to 20°, and even more preferably less than or equal to 18°.

[0051] It should be noted that the acute angle formed by the first cord 36 and the second cord 40 is measured as angle θ3. In one circumferential direction of the tire 2, the value of angle θ3 is taken as positive regardless of whether the second cord 40 is tilted outward in one axial direction or in another. In other words, angle θ3 is the absolute value of the angle formed by the first cord 36 and the second cord 40.

[0052] As previously described, preferably, the second ply 12b is rolled up around each bead 10. The rolled-up portion 34 of the second ply 12b contributes to appropriate stiffness of the sidewalls of the tire 2. At the location where the main portion 32 and the rolled-up portion 34 of the second ply 12b overlap, the inclination directions of the second cords 40 of the main portion 32 and the second cords 40 of the rolled-up portion 34 are opposite to each other. Because the second cords 40 with opposite inclination directions overlap, appropriate stiffness is achieved by overcoming forces from multiple directions. This feature, together with setting the camber angles θ1 and θ2 within the aforementioned range, contributes to achieving excellent handling and cornering performance.

[0053] As previously described, preferably, the first ply 12a is rolled up around each bead 10. The rolled-up portion 30 of the first ply 12a contributes to appropriate stiffness of the sidewalls of the tire 2. This feature, together with setting the camber angles θ1 and θ2 within the aforementioned range, contributes to achieving excellent handling and cornering performance.

[0054] As previously described, at the location where the main portion 32 and the rolled-up portion 34 of the second fabric layer 12b overlap, the second cords 40 with opposite inclination directions overlap. The inclination angle θ2 of the second cords 40 is greater than or equal to 65° and less than or equal to 85°. Therefore, the angle θ4 formed between the second cords 40 with opposite inclination directions is greater than or equal to 10° and less than or equal to 50°. From the viewpoint of achieving excellent handling and cornering performance, the difference between angles θ4 and θ3 (i.e., θ4 - θ3) is preferably greater than or equal to 5°, more preferably greater than or equal to 10°, and even more preferably greater than or equal to 12°. From the same viewpoint, the difference (θ4 - θ3) is preferably less than or equal to 25°, more preferably less than or equal to 20°, and even more preferably less than or equal to 18°.

[0055] like Figure 1 As shown, in the radial direction, the outer ends of the rolled-up portions 30 of the first ply 12a and the second ply 12b are preferably located inside the ends of the tread surface 20. With this configuration, each of the rolled-up portions 30 of the first ply 12a and the second ply 12b is less likely to hinder cornering performance during cornering in the direction of inclination of the second cord 40. The tire 2 constructed in this way exhibits improved cornering performance when cornering in the direction of inclination of the second cord 40. Appropriate lateral stiffness and excellent cornering performance are achieved through the tire 2.

[0056] exist Figure 1In the diagram, the double-headed arrow D1 represents the radial distance between the end of the tread surface 20 and the outer end of the rolled-up portion 30 of the first ply 12a. The distance D1 is preferably greater than or equal to 5 mm. Because the distance D1 is set to be greater than or equal to 5 mm, the rolled-up portion 30 of the first ply 12a is less likely to hinder cornering performance. Therefore, the distance D1 is more preferably greater than or equal to 8 mm, and even more preferably greater than or equal to 10 mm. The distance D1 is preferably less than or equal to 25 mm. Because the distance D1 is set to be less than or equal to 25 mm, the rolled-up portion 30 of the first ply 12a contributes to appropriate lateral stiffness. Therefore, the distance D1 is more preferably less than or equal to 22 mm, and even more preferably less than or equal to 20 mm.

[0057] exist Figure 1 In the diagram, the double-headed arrow D2 represents the radial distance between the end of the tread surface 20 and the outer end of the rolled-up portion 34 of the second ply 12b. Distance D2 is preferably greater than or equal to 1 mm. Because distance D2 is set to be greater than or equal to 1 mm, the rolled-up portion 34 of the second ply 12b is less likely to impede cornering performance. Therefore, distance D2 is more preferably greater than or equal to 3 mm, and even more preferably greater than or equal to 5 mm. Distance D2 is preferably less than or equal to 15 mm. Because distance D2 is set to be less than or equal to 15 mm, the rolled-up portion 34 of the second ply 12b contributes to appropriate lateral stiffness. Therefore, distance D2 is more preferably less than or equal to 12 mm, and even more preferably less than or equal to 10 mm.

[0058] like Figure 1 As shown, in the radial direction, the outer end of the rolled-up portion 34 of the second ply 12b is preferably located outside the outer end of the rolled-up portion 30 of the first ply 12a. The rolled-up portion 34 of the second ply 12b is located further inside the tire 2 than the rolled-up portion 30 of the first ply 12a. Therefore, even if the rolled-up portion 34 of the second ply 12b extends radially outward, the rolled-up portion 34 is unlikely to become an obstacle to cornering performance. Here, by extending the rolled-up portion 34 of the second ply 12b radially outward, the width of the overlapping portion where the main portion 32 of the second ply 12b and the rolled-up portion 34 overlap each other can be extended. As a result, the overlapping portions of the second cords 40 with opposite inclination directions are extended. In this way, appropriate stiffness against forces from multiple directions can be achieved more effectively.

[0059] exist Figure 1In the diagram, the double-headed arrow L represents the radial distance between the outer end of the rolled-up portion 30 of the first fabric layer 12a and the outer end of the rolled-up portion 34 of the second fabric layer 12b. From the viewpoint of achieving high turning performance and appropriate stiffness, the distance L is preferably greater than or equal to 1 mm, more preferably greater than or equal to 3 mm, and even more preferably greater than or equal to 5 mm. From the same viewpoint, the distance L is preferably less than or equal to 15 mm, more preferably less than or equal to 12 mm, and even more preferably less than or equal to 10 mm.

[0060] exist Figure 1 In the diagram, the straight line BBL represents the bead baseline of tire 2. The double-headed arrow H represents the tire's section height. The section height H is the tire's height in the radial direction, measured from the bead baseline BBL at the equator. The double-headed arrow HP1 represents the radial height of the rolled-up portion 30 of the first ply 12a, measured from the bead baseline BBL. The double-headed arrow HP2 represents the radial height of the rolled-up portion 34 of the second ply 12b, measured from the bead baseline BBL.

[0061] The ratio of height HP1 to section height H (HP1 / H) is preferably greater than or equal to 0.10. Since setting the ratio (HP1 / H) to be greater than or equal to 0.10, the rolled-up portion 30 of the first fabric layer 12a contributes to appropriate lateral stiffness. Therefore, the ratio (HP1 / H) is more preferably greater than or equal to 0.15, and even more preferably greater than or equal to 0.20. The ratio (HP1 / H) is preferably less than or equal to 0.35. Since setting the ratio (HP1 / H) to be less than or equal to 0.35, the rolled-up portion 30 of the first fabric layer 12a is less likely to become an obstacle to turning performance. Therefore, the ratio (HP1 / H) is more preferably less than or equal to 0.30, and even more preferably less than or equal to 0.25.

[0062] The ratio of height HP2 to section height H (HP2 / H) is preferably greater than or equal to 0.15. Because the ratio (HP2 / H) is set to be greater than or equal to 0.15, the rolled-up portion 34 of the second fabric layer 12b contributes to appropriate lateral stiffness. Therefore, the ratio (HP2 / H) is more preferably greater than or equal to 0.20, and even more preferably greater than or equal to 0.25. The ratio (HP2 / H) is preferably less than or equal to 0.40. Because the ratio (HP2 / H) is set to be less than or equal to 0.40, the rolled-up portion 34 of the second fabric layer 12b is less likely to become an obstacle to turning performance. Therefore, the ratio (HP2 / H) is more preferably less than or equal to 0.35, and even more preferably less than or equal to 0.30.

[0063] The dimensions and angles of the components of tire 2 are measured with tire 2 fitted in a normal rim and inflated to normal internal pressure. No load is applied to tire 2 during the measurement. In this specification, the term "normal rim" refers to the rim specified according to the standard on which tire 2 is based. The "standard rim" in the JATMA standard, the "design rim" in the TRA standard, and the "measurement rim" in the ETRTO standard are normal rims. In this specification, the term "normal internal pressure" refers to the internal pressure specified according to the standard on which tire 2 is based. The "maximum air pressure" in the JATMA standard, the "maximum value" indicated in "Tire Load Limits at Various Cold Inflation Pressures" in the TRA standard, and the "inflation pressure" in the ETRTO standard are normal internal pressures.

[0064] Example

[0065] The following description illustrates the advantageous effects of tires for two-wheeled motor vehicles based on examples. However, the scope disclosed in this specification should not be interpreted restrictively based on the description of the examples.

[0066] [Example 1]

[0067] Obtain a tire for a two-wheeled motor vehicle according to Example 1, the tire having Figure 1 The structure is shown. The tire size is 120 / 70R17. The tire angles θ1 and θ2 are shown in Table 1.

[0068] [Compare Examples 1 to 5 with Examples 2 to 5]

[0069] In each of Comparative Examples 1 to 5 and Examples 2 to 5, the tires are obtained in the same manner as in Example 1, except that the angles θ1 and θ2 are changed as shown in Tables 1 and 2.

[0070] [Measurement of vertical stiffness constant]

[0071] The vertical stiffness constant was measured for each of the tires in Example 1 and Comparative Examples 1 to 3 under the conditions shown below.

[0072] Wheel rim dimensions used: MT3.50×17

[0073] Internal pressure: 230 kPa

[0074] Load T: 0.54kN, 1.1kN, 1.6kN

[0075] Outward tilt angle Ca: 0 to 50°

[0076] The measurement results of the vertical stiffness constant when the outward tilt angle Ca varies from 0° to 50° are as follows: Figure 5 Each of them is shown in the diagram. Figure 5 (A) shows the measurement results when the load T is 0.54 kN. Figure 5 (B) shows the measurement results when the load T is 1.1 kN. Figure 5 Table (C) shows the measurement results when the load T is 1.6 kN. The measurement results when the load T is 0.54 kN and the outward tilt angle Ca is 20° are shown as indices in Table 1, and the measurement results of Comparative Example 1 are shown as indices 100. A smaller vertical stiffness constant results in better handling and cornering performance. A smaller vertical stiffness constant is preferred. It should be noted that... Figure 5 The proportions of the vertical axis differ in (A), (B), and (C). Therefore, for example, Figure 5 (A) and (B) cannot be compared with each other. Figure 5 Each of (A), (B) and (C) is intended in its own diagram for comparison of Example 1 and Comparisons 1 to 3.

[0077] [Deflection Measurement]

[0078] The deflection was measured for each of the tires in Example 1 and Comparative Examples 1 to 3 under the conditions shown below. The deflection was calculated as the difference between the tire's section height when no load was applied and the tire's section height when a load was applied.

[0079] Wheel rim dimensions used: MT3.50×17

[0080] Internal pressure: 230 kPa

[0081] Load T: 0.54kN, 1.1kN, 1.6kN

[0082] Outward tilt angle Ca: 0 to 50°

[0083] Figure 6 The measurement results of the deflection amount are shown when the outward tilt angle Ca changes from 0° to 50°. Figure 6 (A) shows the measurement results when the load T is 0.54 kN. Figure 6 (B) shows the measurement results when the load T is 1.1 kN. Figure 6 Table (C) shows the measurement results when the load T is 1.6 kN. The measurement results when the load T is 0.54 kN and the camber angle Ca is 20° are shown as indices in Table 1, and the measurement results of Comparative Example 1 are shown as indices 100. A larger yaw rate results in better handling and cornering performance. A larger yaw rate is preferred. It should be noted that... Figure 6 The proportions of the vertical axis differ in (A), (B), and (C). Therefore, for example, Figure 6 (A) and (B) cannot be compared with each other. Figure 6 Each of (A), (B) and (C) is intended in its own diagram for comparison of Example 1 and Comparisons 1 to 3.

[0084] [Handling performance]

[0085] The aforementioned tires were fitted into standard rims (rim size = MT3.50 × 17) and mounted on the front wheel of a two-wheeled vehicle with an engine displacement of 1000cc. The tires were then inflated to an internal pressure of 200 kPa. Conventional tires were mounted on the rear wheel of the two-wheeled vehicle. A rider operated the two-wheeled vehicle on a loop route and conducted a sensory evaluation. Handling performance was assessed through sensory evaluation. The evaluation results are presented in Tables 1 and 2 as four levels: A, B, C, and D. Handling performance was graded alphabetically by A, B, C, and D, with A being the highest and D the lowest; that is, A is the most preferred and D is the least preferred.

[0086] [Table 1]

[0087] Table 1: Evaluation Results

[0088] [Table 2]

[0089] Table 2: Evaluation Results

[0090] like Figures 5 to 6 As shown in Tables 1 and 2, the example tires outperform the comparative example tires in terms of handling performance. These evaluation results clearly demonstrate the superiority of the tires for two-wheeled motor vehicles according to this disclosure.

[0091] [Public Items]

[0092] The following items all disclose preferred embodiments.

[0093] 1. A tire for a two-wheeled motor vehicle, the tire comprising: a pair of bead layers; and a carcass extending over and between the bead layers, wherein the carcass comprises: a first ply comprising a plurality of first cords arranged in parallel; and a second ply stacked outside the first ply layer and comprising a plurality of second cords arranged in parallel. The first cords are inclined relative to the equatorial plane, and each first cord forms an angle θ1 relative to the equatorial plane, the angle θ1 being substantially 90°. The second cords are inclined relative to the equatorial plane, and each second cord forms an angle θ2 relative to the equatorial plane, the angle θ2 being greater than or equal to 65° and less than or equal to 85°.

[0094] 2. The tire for a two-wheeled motor vehicle according to claim 1, wherein the angle θ2 is greater than or equal to 70° and less than or equal to 80°.

[0095] 3. The tire for a two-wheeled motor vehicle according to claim 1 or 2, wherein the second ply is rolled up around each bead such that the second ply includes a rolled-up portion formed around the respective bead.

[0096] 4. The tire for a two-wheeled motor vehicle according to claim 3, wherein the first ply is rolled up around each bead such that the first ply includes a rolled-up portion formed around the respective bead.

[0097] 5. The tire for a two-wheeled motor vehicle according to claim 4, the tire further comprising a tread, the tread comprising a tread surface in contact with the road surface, wherein, in the radial direction, the outer ends of each rolled portion of the first ply and the outer ends of each rolled portion of the second ply are located inside the ends of the tread surface.

[0098] 6. The tire for a two-wheeled motor vehicle according to claim 4 or 5, wherein, in the radial direction, the outer end of each rolled-up portion of the second ply is located outside the outer end of each rolled-up portion of the first ply.

[0099] 7. A tire for a two-wheeled motor vehicle according to any one of claims 4 to 6, wherein, in the radial direction, the ratio of the height of each rolled-up portion of the first ply to the cross-sectional height of the tire is greater than or equal to 0.10 and less than or equal to 0.35, and the ratio of the height of each rolled-up portion of the second ply to the cross-sectional height of the tire is greater than or equal to 0.15 and less than or equal to 0.40.

[0100] Industrial applicability

[0101] The above tires are suitable for all kinds of two-wheeled motor vehicles.

[0102] List of reference numerals

[0103] 2 tires

[0104] 4. Tread

[0105] 6. Sidewalls

[0106] 8 wings

[0107] 10 Beads

[0108] 12 fetuses

[0109] 12a First curtain layer

[0110] 12b Second curtain layer

[0111] 14 belts

[0112] 16 Lining

[0113] 18. Bead wrapping

[0114] 20 Tread surface

[0115] 22 Grooves

[0116] 24 core

[0117] 26 Triangle rubber

[0118] 28, 32 Main parts

[0119] 30, 34 Rolled-up sections

[0120] 36 First Cord

[0121] 38, 42 Top layer rubber

[0122] 40 Second Cord

[0123] 44 First Rubber Sheet

Claims

1. A tire for a two-wheeled motor vehicle, the tire comprising: A pair of tire beads; as well as The tire body extends over and between the tire bead, wherein, The fetal body includes: A first fabric layer, comprising a plurality of first cords arranged in parallel; and The second fabric layer is stacked on the outside of the first fabric layer and includes a plurality of parallel second cords. The first cords are inclined relative to the equatorial plane, and each first cord forms an angle θ1 relative to the equatorial plane as an absolute value, the angle θ1 being greater than or equal to 87° and less than or equal to 90°. The second cord is inclined relative to the equatorial plane, and each second cord forms an angle θ2 relative to the equatorial plane as an absolute value, the angle θ2 being greater than or equal to 65° and less than or equal to 85°. The second ply is rolled up around each tire bead, such that the second ply includes a rolled-up portion formed around the respective tire bead. The first ply is rolled up around each tire bead, such that the first ply includes a rolled-up portion formed around the corresponding tire bead. In the radial direction, the outer end of each rolled-up portion of the second fabric layer, where the inclination of the cord relative to the equatorial plane is relatively small, is located outside the outer end of each rolled-up portion of the first fabric layer, where the inclination of the cord relative to the equatorial plane is relatively large.

2. The tire for a two-wheeled motor vehicle according to claim 1, wherein, The angle θ2 is greater than or equal to 70° and less than or equal to 80°.

3. The tire for a two-wheeled motor vehicle according to claim 1 or 2, the tire further comprising a tread, the tread including a tread surface in contact with the road surface, wherein, In the radial direction, the outer end of each rolled-up portion of the first ply and the outer end of each rolled-up portion of the second ply are located inside the end of the tread surface.

4. The tire for a two-wheeled motor vehicle according to claim 1 or 2, wherein, In the radial direction, The ratio of the height of each rolled-up portion of the first ply to the cross-sectional height of the tire is greater than or equal to 0.10 and less than or equal to 0.

35. The ratio of the height of each rolled-up portion of the second ply to the cross-sectional height of the tire is greater than or equal to 0.15 and less than or equal to 0.40.

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