Motorcycle Tire Pair

Abstract

To provide a tire pair for a two-wheel vehicle which can contribute to improvement of ride quality.SOLUTION: A tire pair is comprised of: a front tire 2; and a rear tire 52. The front tire 2 comprises: a pair of beads 18; a carcass 10 which bridges between one bead 18 and the other bead 18; a tread 4 which is positioned in radial outside of the carcass 10; and a band 14 which is positioned between the tread 4 and the carcass 10 in the radial direction. The carcass 10 includes many carcass cords 30 arranged in parallel, each of the carcass cords 30 is tilted against an equatorial plane. The band 14 includes a band cord 34 which substantially extends in a circumferential direction. A ratio (Jf / Jr) of flexural rigidity Jf of the band cord 34 of the front tire 2 to flexural rigidity Jr of a band cord 84 of the rear tire 52 is 0.0 or more and less than 0.7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pair of tyres for a two-wheeled motor vehicle. [Background technology]

[0002] A band (jointless band (JLB)) including a spirally wound band cord is known as a component of a tire for a motorcycle. For example, in the following Patent Document 1, the strength and space ratio of the band cord are adjusted for each of the front tire and the rear tire, thereby improving the maneuverability and stability of the motorcycle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2567836 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, when a rider is touring, he or she rides a motorcycle for a long period of time. In such a case, the rider attaches importance to a riding comfort. The tire pair disclosed in the above-mentioned Patent Document 1 attaches importance to maneuverability and stability, and does not provide the riding comfort desired by the rider.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a tire pair for a two-wheeled vehicle that can contribute to improving the riding comfort. [Means for solving the problem]

[0006] The present inventors have conducted extensive research aimed at improving the ride comfort of motorcycles, and have found that a study focusing on the bending rigidity of a band cord is effective in improving ride comfort, and that the bending rigidity of the band cord also contributes to ensuring stability, leading to the completion of the present invention. That is, a pair of tires for motorcycles according to one aspect of the present invention comprises a front tire and a rear tire. Each of the front tire and the rear tire includes a pair of beads, a carcass spanning between one bead and the other bead, a tread positioned radially outward of the carcass, and a band positioned radially between the tread and the carcass. The carcass includes a number of carcass cords arranged in parallel, and each carcass cord is inclined with respect to the equatorial plane. The band includes a band cord extending substantially in the circumferential direction. A ratio of the bending rigidity of the band cord of the front tire to the bending rigidity of the band cord of the rear tire is equal to or greater than 0.0 and less than 0.7.

[0007] Preferably, in the pair of tires for a two-wheeled vehicle, the bending stiffness of the band cord of the front tire is less than 15.0 g·cm, and the bending stiffness of the band cord of the rear tire is equal to or greater than 15.0 g·cm and equal to or less than 40.0 g·cm.

[0008] Preferably, in the pair of tires for a motorcycle, the band cord of the front tire is a cord made of aramid fiber, and the band cord of the rear tire is a steel cord.

[0009] Preferably, in the pair of tires for a two-wheeled vehicle, an angle that a carcass cord of the front tire makes with respect to the equatorial plane is smaller than an angle that a carcass cord of the rear tire makes with respect to the equatorial plane.

[0010] Preferably, in this pair of tires for a two-wheeled vehicle, the angle that the carcass cord of the front tire makes with respect to the equatorial plane is equal to or greater than 20° and less than 70°, and the angle that the carcass cord of the rear tire makes with respect to the equatorial plane is equal to or greater than 70°.

[0011] Preferably, in the pair of tires for a motorcycle, a density of a band cord in the band of the front tire is higher than a density of a band cord in the band of the rear tire. Effect of the Invention

[0012] According to the present invention, a tire pair for a two-wheeled vehicle can be obtained that can contribute to improving ride comfort and ensuring stability. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing a part of a front tire constituting a tire pair according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram illustrating the configuration of the carcass and the band in the front tire. [Diagram 3] FIG. 3 is a perspective view showing a portion of a strip used to form the band of a front tire. [Figure 4] FIG. 4 is a cross-sectional view showing a part of a rear tire constituting a tire pair according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic diagram illustrating the configuration of the carcass and the band in the rear tire. [Figure 6] FIG. 6 is a schematic diagram illustrating a method for measuring the bending rigidity of a band cord. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

[0015] In this disclosure, a state in which a tire is mounted on a standard rim, the internal pressure of the tire is adjusted to a standard internal pressure, and no load is applied to the tire is referred to as a standard state.

[0016] In this disclosure, unless otherwise specified, the dimensions and angles of each part of the tire are measured in a normal state. The dimensions and angles of each part in a meridian section of the tire, which cannot be measured when the tire is mounted on a normal rim, are measured by cutting the tire along a plane including the rotation axis, and the distance between the left and right beads in the tire section is measured so as to match the distance between the beads in the tire mounted on a normal rim.

[0017] A genuine rim means a rim specified in the standard on which the tire 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 genuine rims. Unless otherwise specified, the rim in this disclosure means a genuine rim.

[0018] Normal tire pressure means the internal pressure specified in the standard on which the tire is based. The "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are normal tire pressures.

[0019] Normal load refers to the load specified in the standard on which the tire is based. The "maximum load capacity" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard are normal loads.

[0020] A pair of tires for a motorcycle according to one embodiment of the present invention comprises a front tire mounted on the front wheel of the motorcycle and a rear tire mounted on the rear wheel. The front tire and the rear tire will be described below.

[0021] [Front tire] 1 shows a part of a cross section (hereinafter also referred to as a meridian cross section) of a front tire 2 (hereinafter referred to as tire 2) taken along a plane including the rotation axis of the tire 2. In FIG. 1, the left-right direction is the axial direction of the tire 2, and the up-down direction is the radial direction of the tire 2. The direction perpendicular to the plane of FIG. 1 is the circumferential direction of the tire 2. In FIG. 1, the dashed dotted line ELf is the equatorial plane of the tire 2.

[0022] 1, a solid line BLf extending in the axial direction is a bead base line, which defines the rim diameter (see JATMA, etc.) of a rim (not shown) on which the tire 2 is mounted.

[0023] The tire 2 includes a tread 4, a pair of sidewalls 6, a pair of beads 8, a carcass 10, an inner liner 12, and a band 14.

[0024] The tread 4 is made of crosslinked rubber. The outer surface of the tread 4 comes into contact with the road surface. The outer surface of the tread 4 is a tread surface 16. In the meridian cross section shown in FIG. 1, the tread surface 16 is curved so that its equatorial plane portion protrudes radially outward. Grooves 18 are formed in the tread 4. This forms a tread pattern. The grooves 18 do not necessarily have to be formed in the tread 4.

[0025] In FIG. 1 , the position indicated by the symbol Fe is the end of the tread surface 16. The length indicated by the double arrow TWf is the tread width. The tread width TWf is expressed as the axial distance from one end Fe of the tread surface 16 to the other end Fe of the tread surface 16. In this tire 2, the end Fe of the tread surface 16 is the axial outer end of the tire 2. The tread width TWf is also the maximum width of the tire 2.

[0026] Each sidewall 6 is made of crosslinked rubber. The sidewalls 6 are continuous with the ends of the tread 4. The sidewalls 6 are located radially inward of the tread 4. The sidewalls 6 extend radially along the carcass 10.

[0027] Each bead 8 is located radially inward of the sidewall 6. The bead 8 includes a core 20 and an apex 22. Although not shown, the core 20 includes a steel wire. The apex 22 is located radially outward of the core 20. The apex 22 tapers outward. The apex 22 is made of crosslinked rubber having high rigidity.

[0028] The carcass 10 is located on the inside of the tread 4 and the pair of sidewalls 6. The carcass 10 bridges between one bead 8 and the other bead 8. The tread 4 is located on the outside of the carcass 10 in the radial direction.

[0029] The carcass 10 includes at least one carcass ply 24. The carcass 10 of the tire 2 is composed of two carcass plies 24. The carcass ply 24 located radially inward on the inner side of the tread 4 is a first carcass ply 26, and the carcass ply 24 located outward of the first carcass ply 26 is a second carcass ply 28.

[0030] The first carcass ply 26 includes a first ply body 26a that spans between one core 20 and the other core 20, and a pair of first turn-up portions 26b that are connected to the first ply body 26a and turned back around each core 20 from the inside to the outside in the axial direction.

[0031] The second carcass ply 28 includes a second ply body 28a that spans between one core 20 and the other core 20, and a pair of second turn-up portions 28b that are connected to the second ply body 28a and are turned up around each core 20 from the inside to the outside in the axial direction.

[0032] In FIG. 1, the double-headed arrow HF1 indicates the radial distance from the bead base line BLf to the end of the first turned-up portion 26b. The distance HF1 is the height of the first turned-up portion 26b. The double-headed arrow HF2 indicates the radial distance from the bead base line BLf to the end of the second turned-up portion 28b. The distance HF2 is the height of the second turned-up portion 28b. In this tire 2, the height HF1 of the first turned-up portion 26b is higher than the height HF2 of the second turned-up portion 28b. The height HF1 of the first turned-up portion 26b may be lower than the height HF2 of the second turned-up portion 28b.

[0033] Fig. 2 shows the configuration of the carcass 10 together with a band 14 described later. In Fig. 2, the left-right direction is the axial direction of the tire 2, and the up-down direction is the circumferential direction of the tire 2. The direction perpendicular to the paper surface is the radial direction of the tire 2. The front side of the paper surface is the radial outer side, and the back side is the radial inner side.

[0034] As shown in Fig. 2, each carcass ply 24 constituting the carcass 10 includes a number of parallel carcass cords 30. In Fig. 2, for convenience of explanation, the carcass cords 30 are represented by solid lines, but the carcass cords 30 are covered with a topping rubber 32.

[0035] Each carcass cord 30 is inclined with respect to the equatorial plane. As shown in Fig. 2, the direction of inclination of the carcass cord 30 in the first carcass ply 26 is opposite to the direction of inclination of the carcass cord 30 in the second carcass ply 28. In Fig. 2, the angle indicated by the symbol θ1f is the angle that the carcass cord 30 in the first carcass ply 26 makes with respect to the equatorial plane. The angle indicated by the symbol θ2f is the angle that the carcass cord 30 in the second carcass ply 28 makes with respect to the equatorial plane. In this tire 2, the inclination angle θ1f and the inclination angle θ2f are the same.

[0036] In the present disclosure, the average value of the angles θ1f and θ2f is used as the angle θf that the carcass cord 30 makes with respect to the equatorial plane (hereinafter also referred to as the inclination angle θf of the carcass cord 30). The inclination angle θr of the carcass cord of the rear tire, which will be described later, is also expressed in the same manner as the tire 2.

[0037] The carcass cord 30 is a cord made of organic fibers, such as nylon fibers, rayon fibers, polyester fibers, and aramid fibers.

[0038] The inner liner 12 is positioned inside the carcass 10. The inner liner 12 constitutes the inner surface of the tire 2. The inner liner 12 is made of a crosslinked rubber having a low gas permeability coefficient. The inner liner 12 maintains the internal pressure of the tire 2.

[0039] The band 14 is located between the tread 4 and the carcass 10 in the radial direction. As shown in FIG. 1, the band 14 is laminated on the carcass 10. The position indicated by the symbol Bf is the end of the band 14. The length indicated by the double arrow BWf is the width of the band 14. The width BWf of the band 14 is represented by the axial distance from one end Bf of the band 14 to the other end Bf of the band 14. In the tire 2, the ratio (BWf / TWf) of the width BWf of the band 14 to the tread width TWf is 0.80 or more and 0.95 or less.

[0040] The band 14 includes a spirally wound band cord 34. In Fig. 2, for convenience of explanation, the band cord 34 is represented by a solid line, but the band cord 34 is covered with a topping rubber 36. In the tire 2, the band cord 34 extends substantially in the circumferential direction. In detail, the angle that the band cord 34 forms with the circumferential direction is 5° or less. The band 14 is also called a jointless band.

[0041] The band cord 34 is a cord made of a steel cord or an organic fiber. Examples of the organic fiber include nylon fiber, rayon fiber, polyester fiber, and aramid fiber.

[0042] The band 14 is formed using a strip 38 in FIG. 3. The strip 38 is tape-shaped. The strip 38 is made of a band cord 34 and a topping rubber 36. In the strip 38, the topping rubber 36 is in an unvulcanized state. The strip 38 includes a plurality of band cords 34 arranged in parallel in the width direction. The number of band cords 34 included in the strip 38 may be one. Although not described in detail, the band 14 is formed by winding the strip 38 spirally in the circumferential direction.

[0043] Although not shown, the cross sections of a large number of band cords 34 are arranged in a row in a cross section of the band 14 included in a meridian cross section of the tire 2. In other words, the band 14 of the tire 2 is composed of one band ply.

[0044] In this tire 2, the number of cross sections of the band cords 34 contained per 5 cm width of the cross section of the band 14 obtained in a 10 cm wide zone centered on the equatorial plane in the meridian cross section is expressed as the density Df of the band cords 34 in the band 14. The unit of the density Df of the band cords 34 is ends / 5 cm. The density Dr of the band cords of the rear tire, which will be described later, is also expressed in the same way as this tire 2.

[0045] In the tire 2, from the viewpoint of ensuring puncture resistance, the density Df of the band cord 34 in the band 14 is preferably 30 ends / 5 cm or more. From the viewpoint of weight reduction, the density Df of the band cord 34 is preferably 50 ends / 5 cm or less.

[0046] [Rear tire] 4 shows a portion of a meridian cross section of a rear tire 52 (hereinafter, tire 52). In FIG. 4, the left-right direction is the axial direction of the tire 52, and the up-down direction is the radial direction of the tire 52. The direction perpendicular to the plane of FIG. 4 is the circumferential direction of the tire 52. In FIG. 4, dashed dotted line ELr is the equatorial plane of the tire 52.

[0047] 4, a solid line BLr extending in the axial direction is a bead base line, which defines the rim diameter (see JATMA, etc.) of a rim (not shown) on which the tire 52 is mounted.

[0048] The tire 52 includes a tread 54 , a pair of sidewalls 56 , a pair of beads 58 , a carcass 60 , an inner liner 62 , and a band 64 .

[0049] The tread 54 is made of crosslinked rubber. The tread 54 comes into contact with the road surface at a tread surface 66. In a meridian cross section, the tread surface 66 is curved such that its equatorial plane portion protrudes radially outward. Grooves 68 are formed in the tread 54. This forms a tread pattern. The grooves 68 do not necessarily have to be formed in the tread 54.

[0050] 4, the position indicated by the symbol Re is the edge of the tread surface 66. The length indicated by the double arrow TWr is the tread width. In this tire 52 as well, the edge Re of the tread surface 66 is the outer end of the tire 52 in the axial direction.

[0051] Each sidewall 56 is made of crosslinked rubber. The sidewalls 56 are continuous with the ends of the tread 54. The sidewalls 56 are located radially inward of the tread 54. The sidewalls 56 extend radially along the carcass 60.

[0052] Each bead 58 is located radially inward of the sidewall 56. The bead 58 includes a core 70 and an apex 72. Although not shown, the core 70 includes a steel wire. The apex 72 is located radially outward of the core 70. The apex 72 tapers outward. The apex 72 is made of crosslinked rubber having high rigidity.

[0053] The carcass 60 is located on the inside of the tread 54 and the pair of sidewalls 56. The carcass 60 bridges between one bead 58 and the other bead 58. The tread 54 is located on the outside of the carcass 60 in the radial direction.

[0054] The carcass 60 includes at least one carcass ply 74. The carcass 60 of the tire 52 is composed of two carcass plies 74, that is, a first carcass ply 76 and a second carcass ply 78.

[0055] The first carcass ply 76 includes a first ply body 76a that spans between one core 70 and the other core 70, and a pair of first turn-up portions 76b that are connected to the first ply body 76a and are turned up from the axially inner side to the axially outer side around each core 70.

[0056] The second carcass ply 78 includes a second ply body 78a that spans between one core 70 and the other core 70, and a pair of second turn-up portions 78b that are connected to the second ply body 78a and are turned back around each core 70 from the axial inside to the axial outside.

[0057] 1, the double-headed arrow HR1 indicates the height of the first turned-up portion 76b. The double-headed arrow HR2 indicates the height of the second turned-up portion 78b. In this tire 52, the height HR1 of the first turned-up portion 76b is higher than the height HR2 of the second turned-up portion 78b. The height HR1 of the first turned-up portion 76b may be lower than the height HR2 of the second turned-up portion 78b.

[0058] Fig. 5 shows the configuration of the carcass 60 together with a band 64, which will be described later. In Fig. 5, the left-right direction is the axial direction of the tire 52, and the up-down direction is the circumferential direction of the tire 52. The direction perpendicular to the paper surface is the radial direction of the tire 52. The front side of the paper surface is the radial outer side, and the back side is the radial inner side.

[0059] 5, each carcass ply 74 includes a number of parallel carcass cords 80. In this Fig. 5, for convenience of explanation, the carcass cords 80 are represented by solid lines, but the carcass cords 80 are covered with a topping rubber 82.

[0060] Each carcass cord 80 is inclined with respect to the equatorial plane. As shown in Fig. 5, the direction of inclination of the carcass cord 80 in the first carcass ply 76 is opposite to the direction of inclination of the carcass cord 80 in the second carcass ply 78. In Fig. 5, the angle indicated by the symbol θ1r is the angle that the carcass cord 80 in the first carcass ply 76 makes with respect to the equatorial plane. The angle indicated by the symbol θ2r is the angle that the carcass cord 80 in the second carcass ply 78 makes with respect to the equatorial plane. In this tire 52, the inclination angle θ1r and the inclination angle θ2r are the same.

[0061] In the tire 52, the carcass cord 80 is a cord made of an organic fiber. Examples of the organic fiber include nylon fiber, rayon fiber, polyester fiber, and aramid fiber.

[0062] The inner liner 62 is positioned inside the carcass 60. The inner liner 62 constitutes the inner surface of the tire 52. The inner liner 62 is made of crosslinked rubber with a low gas permeability coefficient. The inner liner 62 maintains the internal pressure of the tire 52.

[0063] The band 64 is located between the tread 54 and the carcass 60 in the radial direction. As shown in Fig. 4, the band 64 is laminated on the carcass 60. This band 64, like the band 14 of the front tire 2, is made of one band ply.

[0064] 4, the position indicated by the symbol Br is the end of the band 64. The length indicated by the double arrow BWr is the width of the band 64. In the tire 52, the ratio (BWr / TWr) of the width BWr of the band 64 to the tread width TWr is equal to or greater than 0.80 and equal to or less than 0.95.

[0065] The band 64 includes a spirally wound band cord 84. In Fig. 5, the band cord 84 is also shown by a solid line for convenience of explanation, but the band cord 84 is covered with a topping rubber 86. In the tire 52, the band cord 84 extends substantially in the circumferential direction. In detail, the angle that the band cord 84 forms with the circumferential direction is 5° or less.

[0066] The band cord 84 is a cord made of a steel cord or an organic fiber. Examples of the organic fiber include nylon fiber, rayon fiber, polyester fiber, and aramid fiber.

[0067] Although not shown, a strip is used to form the band 64, similar to the band 14 of the front tire 2. Although not described in detail, the band 64 is formed by winding the strip spirally in the circumferential direction.

[0068] In the tire 52, from the viewpoint of ensuring puncture resistance, the density Dr of the band cord 84 in the band 64 is preferably 30 ends / 5 cm or more. From the viewpoint of weight reduction, the density Dr of the band cord 84 is preferably 50 ends / 5 cm or less.

[0069] [Tire pair] The present inventors have conducted extensive research aimed at improving the ride comfort of two-wheeled vehicles and have found that focusing on the bending rigidity of a band cord is effective in improving the ride comfort, and that the bending rigidity of a band cord also contributes to ensuring stability, thus completing the present invention.

[0070] In this disclosure, the bending rigidity of a band cord is the average value of the bending moment at +15 degrees and the bending moment at -15 degrees. The unit of bending rigidity is g·cm, and the bending rigidity is expressed as a value rounded off to one decimal place. When the bending rigidity of a band cord is so small that it cannot be measured, the bending rigidity of the band cord is expressed as 0.0 g·cm. The bending moment at +15 degrees and the bending moment at -15 degrees are obtained as follows, for example, using a rigidity tester (e.g., 150-D type) manufactured by Taber Inc. (USA). A band cord (length = 145 mm) is sampled from the band of the tire. As shown in FIG. 6, both ends of a band cord (designated B in FIG. 6) are attached to clamps (designated K in FIG. 6). One clamp K is moved relative to the other clamp K, and bending angles of +15 degrees and -15 degrees are applied to the band cord B. The bending moment when a bending angle of +15 degrees is applied is obtained as the bending moment at +15 degrees, and the bending moment when a bending angle of -15 degrees is applied is obtained as the bending moment at -15 degrees.

[0071] In a single tire, a band cord with low bending rigidity contributes to improving ride comfort. If the bending rigidity of the band cord is excessively low, the tire will deform significantly when a high load is applied to the tire. A tire with a large amount of deformation reduces stability. In motorcycles, the rear wheel side of the vehicle body is heavier than the front wheel side due to its structure. When traveling at high speeds, lift is generated, making the rear wheel even heavier. For this reason, the band cord of the rear tire attached to the rear wheel needs to have a certain degree of bending rigidity. Thus, in a single tire, it is difficult to achieve a good balance between ride comfort and stability even if the bending rigidity of the band cord is adjusted.

[0072] Therefore, the inventors focused on the fact that the front tires make a greater contribution to ride comfort and the rear tires make a greater contribution to stability, and after extensive research, discovered that by using a band cord with low bending rigidity for the front tires and a band cord with high bending rigidity for the rear tires, a good balance between ride comfort and stability can be achieved for the pair of tires, and also discovered that if the ratio of the bending rigidity of the band cord of the front tire to the bending rigidity of the band cord of the rear tire is set to 0.7 or more, the front tire will cause a decrease in ride comfort and the rear tire will cause a decrease in stability.

[0073] That is, in this tire pair, the ratio (Jf / Jr) of the bending rigidity Jf of the band cord 34 of the front tire 2 to the bending rigidity Jr of the band cord 84 of the rear tire 52 is equal to or greater than 0.0 and less than 0.7. In this tire pair, the front tire 2 contributes to improving ride comfort, and the rear tire 52 contributes to ensuring stability. With this tire pair consisting of the front tire 2 and rear tire 52, good ride comfort and stability can be obtained. With this tire pair, it is possible to improve ride comfort and ensure stability, which could not be achieved by tuning the band cord of a single tire.

[0074] In this tire pair, the bending stiffness Jf of the band cord 34 of the front tire 2 is preferably less than 15.0 g·cm, and the bending stiffness Jr of the band cord 84 of the rear tire 52 is preferably 15.0 g·cm or more and 40.0 g·cm or less.

[0075] Setting the bending stiffness Jf of the band cord 34 of the front tire 2 to less than 15.0 g·cm suppresses deterioration of ride comfort caused by the front tire 2. From this viewpoint, it is more preferable that the bending stiffness Jf is 10.0 g·cm or less. From the viewpoint of ride comfort, the lower the bending stiffness Jf, the better, so no preferable lower limit is set for the bending stiffness Jf.

[0076] Setting the bending stiffness Jr of the band cord 84 of the rear tire 52 to 15.0 g·cm or more suppresses a decrease in stability caused by the rear tire 52. Setting the bending stiffness Jr to 40.0 g·cm or less suppresses a decrease in ride comfort caused by the rear tire 52. From this viewpoint, it is more preferable that the bending stiffness Jr be 30 g·cm or less.

[0077] From the viewpoint of obtaining a good ride comfort and stability, it is more preferable that the bending rigidity Jf of the band cord 34 of the front tire 2 is 10.0 g·cm or less, and the bending rigidity Jr of the band cord 84 of the rear tire 52 is 15.0 g·cm or more and 30.0 g·cm or less.

[0078] As described above, the band cord 34 of the front tire 2 is a cord made of a steel cord or an organic fiber. Since the band cord 34 is configured to have a low bending rigidity Jf, when a steel cord is used as the band cord 34, a steel cord with a small diameter is used. In this case, the strength of the band cord 34 is reduced, and there is a risk that the water pressure resistant burst strength of the front tire 2 may not clear a predetermined standard. When a cord made of an organic fiber other than aramid fiber is used as the band cord 34 as a cord made of an organic fiber, the binding force of the band 14 may be insufficient, and high-speed stability may decrease. From the viewpoint of preventing a decrease in water pressure resistant burst strength and high-speed stability caused by the band 14, in this tire pair, it is preferable that the band cord 34 of the front tire 2 is a cord made of aramid fiber. By checking the water pressure resistant burst strength of the tire, the durability of the tire when the tire is overfilled with air can be understood.

[0079] As described above, the band cord 84 of the rear tire 52 is a cord made of a steel cord or an organic fiber. Since this band cord 84 has a high bending rigidity Jr, when a cord made of an organic fiber is used as the band cord 84, a cord made of a thick organic fiber is used. In this case, the proportion of the band cord 84 in the band 64 increases, and the amount of the topping rubber 86 covering the band cord 84 decreases. If the band cord 84 cannot be covered with a sufficient amount of the topping rubber 86, the topping rubber 86 is likely to peel off from the band cord 84, and the durability of the rear tire 52 may decrease. From the viewpoint of preventing a decrease in durability caused by the band 64, it is preferable that the band cord 84 of the rear tire 52 in this tire pair is a steel cord.

[0080] In this tire pair, the band cord 34 having a low bending stiffness Jf is used for the band 14 of the front tire 2, so that the stress is reduced when the front tire 2 has a slip angle. Depending on the degree of the reduction in stress, there is a risk of loss of cornering performance. However, in this tire pair, the inclination angle θf of the carcass cord 30 of the front tire 2 is smaller than the inclination angle θr of the carcass cord 80 of the rear tire 52. A small inclination angle θf increases the stress when the front tire 2 has a slip angle, so the turning force of the front tire 2 is stronger than that of the rear tire 52. In this tire pair, the turning performance of the two-wheeled vehicle is improved, even though the band cord 34 having a low bending rigidity Jf is used for the band 14 of the front tire 2. From this viewpoint, it is preferable that the inclination angle θf of the carcass cord 30 of the front tire 2 is smaller than the inclination angle θr of the carcass cord 80 of the rear tire 52. Specifically, the difference (θr-θf) between the inclination angle θr of the carcass cord 80 of the rear tire 52 and the inclination angle θf of the carcass cord 30 of the front tire 2 is preferably 5° or more, more preferably 8° or more. This difference (θr-θf) is preferably 25° or less, more preferably 20° or less.

[0081] In this tire pair, it is preferable that the inclination angle θf of the carcass cord 30 of the front tire 2 is equal to or greater than 20° and less than 70°, and the inclination angle θr of the carcass cord 80 of the rear tire 52 is equal to or greater than 70°.

[0082] By setting the inclination angle θf to 20° or more, the rigidity of the carcass 10 in the front tire 2 is appropriately maintained, so that a good ride comfort is maintained. From this viewpoint, the inclination angle θf is more preferably 30° or more, and further preferably 40° or more. And, by setting the inclination angle θf to less than 70°, the carcass 10 contributes to improving the cornering performance. From this viewpoint, the inclination angle θf is more preferably 68° or less, and further preferably 65° or less.

[0083] By setting the inclination angle θr to 70° or more, the rigidity of the carcass 60 in the rear tire 52 is appropriately maintained. Since the contribution to turning performance of the rear tire 52 and the contribution to turning performance of the front tire 2 are well balanced, the two-wheeled vehicle maintains good agility. This tire pair can effectively contribute to improving turning performance. From this viewpoint, the inclination angle θr is more preferably 72° or more, and further preferably 80° or more. The upper limit of the inclination angle θr is 90°.

[0084] The density of the band cord in the band affects the stress when the tire has a slip angle. The higher the density of the band cord, the greater the stress generated when the tire has a slip angle. The greater the stress, the greater the turning ability of the tire.

[0085] In this tire pair, the density Df of the band cord 34 in the band 14 of the front tire 2 is higher than the density Dr of the band cord 84 in the band 64 of the rear tire 52. Therefore, the turning force of the front tire 2 is higher than the turning force of the rear tire 52. In this tire pair, the turning performance of the two-wheeled vehicle is improved despite the band cord 34 having a low bending rigidity Jf being used in the band 14 of the front tire 2. From this viewpoint, it is preferable that the density Df of the band cord 34 in the band 14 of the front tire 2 is higher than the density Dr of the band cord 84 in the band 64 of the rear tire 52. Specifically, the ratio (Df / Dr) of the density Df of the band cord 34 in the band 14 of the front tire 2 to the density Dr of the band cord 84 in the band 64 of the rear tire 52 is preferably 1.1 or more, and more preferably 1.2 or more. In light of achieving a good balance between the rigidity of the front tire 2 and the rigidity of the rear tire 52, the ratio (Df / Dr) is preferably equal to or less than 1.4, and more preferably equal to or less than 1.3.

[0086] As described above, according to the present invention, a tire pair for a two-wheeled vehicle can be obtained that can contribute to improving ride comfort and ensuring stability. EXAMPLES

[0087] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0088] [Example 1] A pair of tires for a motorcycle was obtained, consisting of a front tire (120 / 70ZR17) having the basic configuration shown in FIG. 1 and the specifications shown in Table 1 below, and a rear tire (180 / 55ZR17) having the basic configuration shown in FIG. 4 and the specifications shown in Table 1 below. In the front tire of Example 1, a cord made of aramid fiber was used for the band cord. This is shown as "K" for the band cord in column F of Table 1. The bending rigidity Jf and density Df of the band cord, and the inclination angle θf of the carcass cord are as shown in Table 1 below. In this front tire, a cord made of rayon fiber was used for the carcass cord. The structure of the carcass cord was 1840 dtex / 2. The height HF1 of the first turned-up portion was 45 mm, and the height HF2 of the second turned-up portion was 20 mm. In the rear tire of Example 1, a steel cord was used for the band cord. This is indicated by "S" for the band cord in column R of Table 1. The bending rigidity Jr and density Dr of the band cord, and the inclination angle θr of the carcass cord are as shown in Table 1 below. In this rear tire, a cord made of rayon fiber was used for the carcass cord. The structure of the carcass cord was 1840 dtex / 2. The height HR1 of the first turned-up portion was 50 mm, and the height HR2 of the second turned-up portion was 30 mm.

[0089] [Example 2] A tire pair of Example 2 was obtained in the same manner as Example 1, except that the inclination angle θr of the carcass cords of the rear tires was set as shown in Table 1 below.

[0090] [Example 3] A tire pair of Example 3 was obtained in the same manner as Example 2, except that the inclination angle θf of the carcass cords of the front tires was set as shown in Table 1 below.

[0091] [Example 4] A tire pair of Example 4 was obtained in the same manner as in Example 3, except that the density Df of the band cord of the front tire was set as shown in Table 1 below.

[0092] [Examples 5-10 and Comparative Examples 1-3] Tire pairs of Examples 5-10 and Comparative Examples 1-3 were obtained in the same manner as in Example 1, except that the specifications of the band cord of the front tire and the band cord of the rear tire were as shown in Tables 1 and 2 below.

[0093] [Handling stability] The front tire was mounted on a rim (MT3.50x17) and inflated to adjust the internal tire pressure to 250kPa. The rear tire was mounted on a rim (MT5.50x17) and inflated to adjust the internal tire pressure to 290kPa. The front and rear tires were mounted on a large motorcycle (engine displacement = 1300cc). The motorcycle was run on a test course with a dry asphalt surface, and a test rider performed a sensory evaluation (on a 5-point scale) for ride comfort, stability, and turning ability. The results are shown as indices in Tables 1 and 2 below. The handling stability column in Tables 1 and 2 lists the total index value for each item. The higher the value, the better.

[0094] [Durability] The prototype tire (rear tire) was run on a drum test machine under the following conditions. After running, the state of breakage of each cord and the state of peeling of each component were visually checked. The results are shown as indices in Tables 1 and 2 below. The higher the value, the more durable the tire is. Rim: MT5.50×17 Internal pressure: 235kPa Speed: 80km / h Vertical load: 4.41kN Mileage: 16,000km

[0095] [Water pressure resistance] A prototype tire (front tire) was mounted on a rim (MT3.50 x 17), and water was filled inside the tire to increase the internal pressure and destroy the tire. The pressure at which the tire was destroyed was measured. The results are shown as indices in Tables 1 and 2 below. The higher the value, the higher the tire's water pressure destruction strength.

[0096] [Table 1]

[0097] [Table 2]

[0098] As shown in Table 1-2, it has been confirmed that the tire pair of the embodiment can contribute to improving the ride comfort and ensuring stability. From this evaluation result, the superiority of the present invention is clear. [Industrial Applicability]

[0099] The techniques described above that can contribute to improving ride comfort and ensuring stability can also be applied to tire pairs for various two-wheeled vehicles. [Explanation of symbols]

[0100] 2. Front tire 4, 54...Tread 8, 58... Bead 10, 60... Carcass 14, 64... band 24, 26, 28, 74, 76, 78...Carcass ply 30, 80... Carcass cord 34, 84...Band cord 38. Strip 52···Rear tire

Claims

1. A tire pair consisting of a front tire and a rear tire, Each of the front tires and the rear tires is The tire comprises a pair of beads, a carcass extending between one bead and the other bead, a tread positioned radially outward of the carcass, and a band positioned radially between the tread and the carcass, The carcass includes a number of carcass cords arranged in parallel, each of the carcass cords being inclined with respect to an equator plane, The band includes a band cord extending substantially in a circumferential direction, a ratio of a bending rigidity of the band cord of the front tire to a bending rigidity of the band cord of the rear tire is 0.0 or more and less than 0.7, The bending rigidity of the band cord of the front tire is less than 15.0 g cm, The bending rigidity of the band cord of the rear tire is 15.0 g cm or more and 40.0 g cm or less. Pair of tyres for motorcycles.

2. The band cord of the front tire is a cord made of aramid fiber, The band cord of the rear tire is a steel cord. A pair of tyres for a two-wheeled motor vehicle according to claim 1.

3. an angle that the carcass cord of the front tire makes with respect to the equatorial plane is smaller than an angle that the carcass cord of the rear tire makes with respect to the equatorial plane; A pair of tyres for a two-wheeled motor vehicle according to claim 1 or 2.

4. The angle that the carcass cord of the front tire makes with respect to the equatorial plane is equal to or greater than 20° and less than 70°, The angle of the carcass cord of the rear tire with respect to the equator plane is 70° or more. A pair of tyres for a two-wheeled motor vehicle according to claim 3.

5. a density of a band cord in the band of the front tire is higher than a density of a band cord in the band of the rear tire; A pair of tyres for a two-wheeled motor vehicle according to any one of claims 1 to 4.

6. A tire pair consisting of a front tire and a rear tire, Each of the front tires and the rear tires is The tire comprises a pair of beads, a carcass extending between one bead and the other bead, a tread positioned radially outward of the carcass, and a band positioned radially between the tread and the carcass, The carcass includes a number of carcass cords arranged in parallel, each of the carcass cords being inclined with respect to an equator plane, The band includes a band cord extending substantially in a circumferential direction, a ratio of a bending rigidity of the band cord of the front tire to a bending rigidity of the band cord of the rear tire is 0.0 or more and less than 0.7, a density of a band cord in the band of the front tire is higher than a density of a band cord in the band of the rear tire; Pair of tyres for motorcycles.

7. The bending stiffness of the band cord of the front tire is less than 15.0 g cm, The bending rigidity of the band cord of the rear tire is 15.0 g cm or more and 40.0 g cm or less. A pair of tyres for a two-wheeled motor vehicle according to claim 6.

8. The band cord of the front tire is a cord made of aramid fiber, The band cord of the rear tire is a steel cord. A pair of tyres for a two-wheeled motor vehicle according to claim 6 or 7.

9. An angle that the carcass cord of the front tire makes with respect to the equatorial plane is smaller than an angle that the carcass cord of the rear tire makes with respect to the equatorial plane. A pair of tyres for a two-wheeled motor vehicle according to any one of claims 6 to 8.

10. The angle that the carcass cord of the front tire makes with respect to the equatorial plane is greater than or equal to 20° and less than 70°, The angle of the carcass cord of the rear tire with respect to the equator plane is 70° or more. A pair of tyres for a two-wheeled motor vehicle according to claim 9.

Images