Two-wheeled vehicle tire pair

Abstract

The present invention provides a pair of tires for a two-wheeled motor vehicle, which can help improve riding comfort. The tire pair is composed of a front tire (2) and a rear tire (52). The front tire (2) has: a pair of beads (18); a carcass (10) that is mounted between one bead (18) and the other bead (18); a tread (4) that is radially located outside the carcass (10); and a cap band (14) that is radially located between the tread (4) and the carcass (10). The carcass (10) includes a plurality of carcass cords (30) arranged in parallel, each carcass cord (30) being inclined relative to the equatorial plane. The cap band (14) includes a cap band cord (34) that extends substantially in the circumferential direction. 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 greater than 0.0 and less than 0.7.

Description

Technical Field

[0001] The present invention relates to a pair of tires for two-wheeled vehicles. Background Art

[0002] As a component of a motorcycle tire, a cap band (jointless cap band (JLB)) comprising a helically wound cap band cord is known. For example, Patent Document 1 below describes improving the maneuverability and stability of a motorcycle by adjusting the strength and space ratio of the cap band cord for the front and rear tires, respectively.

[0003] Patent Document 1: Japanese Patent No. 2567836

[0004] However, during travel, riders often ride on a two-wheeled vehicle for long periods of time. In such situations, riders place great emphasis on ride comfort. The tire pair disclosed in Patent Document 1 emphasizes maneuverability and stability, but fails to provide the ride comfort that riders desire. Summary of the Invention

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pair of tires for a motorcycle that can contribute to improving ride comfort.

[0006] The inventors conducted intensive research with the goal of improving the ride comfort of motorcycles and discovered that focusing on the flexural rigidity of the band cord is effective for improving ride comfort. They also discovered that the flexural rigidity of the band cord contributes to ensuring stability, leading to the completion of the present invention. Specifically, one embodiment of the present invention provides a pair of motorcycle tires comprising a front tire and a rear tire. The front and rear tires each include: a pair of beads; a carcass spanning between one bead and the other; a tread radially outwardly of the carcass; and a band radially positioned between the tread and the carcass. The carcass includes a plurality of carcass cords arranged in parallel, each carcass cord being inclined relative to the equatorial plane. The band includes a band cord extending substantially circumferentially. The ratio of the flexural rigidity of the band cord of the front tire to the flexural rigidity of the band cord of the rear tire is 0.0 or greater and less than 0.7.

[0007] In this pair of motorcycle tires, the band cords of the front tire preferably have a bending rigidity of less than 15.0 g·cm, and the band cords of the rear tire preferably have a bending rigidity of 15.0 g·cm to 40.0 g·cm.

[0008] In the pair of motorcycle tires, it is preferred that the band cords of the front tire are cords made of aramid fiber, and the band cords of the rear tire are steel cords.

[0009] In the pair of motorcycle tires, the angle formed between the carcass cords of the front tire and the equatorial plane is preferably smaller than the angle formed between the carcass cords of the rear tire and the equatorial plane.

[0010] In this pair of motorcycle tires, the angle between the carcass cords of the front tire and the equatorial plane is preferably 20° or more and less than 70°, and the angle between the carcass cords of the rear tire and the equatorial plane is preferably 70° or more.

[0011] In the pair of motorcycle tires, it is preferable that the density of the band cords in the band of the front tire is higher than the density of the band cords in the band of the rear tire.

[0012] According to the present invention, a pair of tires for a motorcycle can be obtained that can contribute to improving riding comfort and ensuring stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a cross-sectional view showing a portion of a front tire constituting a tire pair according to one embodiment of the present invention.

[0014] Figure 2 This is a schematic diagram illustrating the structure of the carcass and cap band of a front tire.

[0015] Figure 3 It is a perspective view showing a portion of a strip forming a cap band of a front tire.

[0016] Figure 4 This is a cross-sectional view showing a portion of a rear tire constituting a tire pair according to one embodiment of the present invention.

[0017] Figure 5 This is a schematic diagram illustrating the structure of the carcass and cap band of the rear tire.

[0018] Figure 6 This is a schematic diagram explaining a method for measuring the bending rigidity of a band cord.

[0019] Description of labels

[0020] 2: front tire; 4, 54: tread; 8, 58: bead; 10, 60: carcass; 14, 64: cap band; 24, 26, 28, 74, 76, 78: carcass ply; 30, 80: carcass cord; 34, 84: cap band cord; 38: strip; 52: rear tire. DETAILED DESCRIPTION

[0021] Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

[0022] In the present disclosure, a state in which a tire is assembled on a regular rim, the internal pressure of the tire is adjusted to a regular internal pressure, and no load is applied to the tire is referred to as a regular state.

[0023] Unless otherwise specified, the dimensions and angles of various tire components are measured under normal conditions. Dimensions and angles of various components in a meridian cross-section of the tire, which cannot be measured when the tire is assembled on a normal rim, are obtained by cutting the tire along a plane containing the axis of rotation. In the cross-section, the distance between the left and right beads is aligned with the distance between the beads of a tire assembled on a normal rim.

[0024] A regular rim is a rim specified in the tire's specifications. JATMA's "standard rim," TRA's "design rim," and ETRTO's "measuring rim" are all regular rims. Unless otherwise specified, the term "rim" in this disclosure refers to a regular rim.

[0025] The normal internal pressure is the internal pressure specified in the tire's standards. The normal internal pressure is specified in the JATMA standard's "Maximum Air Pressure," the maximum value specified in the TRA standard's "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and the ETRTO standard's "INFLATION PRESSURE."

[0026] The normal load is the load specified in the tire's specifications. These include the "maximum load capacity" in the JATMA standard, the "maximum value" specified in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" section of the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard.

[0027] A motorcycle tire pair 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.

[0028] [Front tire]

[0029] Figure 1 A portion of a cross section (hereinafter also referred to as a meridian cross section) of the front tire 2 (hereinafter referred to as the tire 2) along a plane including the rotation axis of the tire 2 is shown. Figure 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 . Figure 1 The direction perpendicular to the paper is the circumferential direction of the tire 2. Figure 1In FIG, a dashed line ELf is the equatorial plane of the tire 2 .

[0030] exist Figure 1 In FIG, a solid line BLf extending in the axial direction is a bead base line. The bead base line BLf is a line that defines the rim diameter (see JATMA, etc.) of a rim (not shown) on which the tire 2 is mounted.

[0031] 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 cap band 14 .

[0032] The tread 4 is made of cross-linked rubber. The tread 4 contacts the road surface at its outer surface. The outer surface of the tread 4 is the tread surface 16. Figure 1 In the meridian cross section shown, the tread surface 16 is curved so that its equatorial portion protrudes radially outward. Grooves 18 are engraved on the tread 4. This forms a tread pattern. The tread 4 may not have grooves 18 engraved on it.

[0033] exist Figure 1 In the figure, the position indicated by the symbol Fe is the end of the tread surface 16. The length indicated by the double-headed arrow TWf is the tread width. The tread width TWf is represented by 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.

[0034] Each sidewall 6 is made of cross-linked rubber. The sidewall 6 is connected to the end of the tread 4. The sidewall 6 is located radially inside the tread 4. The sidewall 6 extends radially along the carcass 10.

[0035] Each bead 8 is radially located inward of the sidewall 6. Each bead 8 includes a core 20 and an apex 22. Although not shown, the core 20 is made of a steel wire rod. The apex 22 is radially located outward of the core 20. The apex 22 tapers toward the outer tip. The apex 22 is made of highly rigid cross-linked rubber.

[0036] The carcass 10 is located inside the tread 4 and the pair of sidewalls 6. The carcass 10 is spanned between one bead 8 and the other bead 8. The tread 4 is located outside the carcass 10 in the radial direction.

[0037] 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 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.

[0038] The first carcass ply 26 includes a first ply main body 26a spanned between one core 20 and the other core 20 and a pair of first folded portions 26b connected to the first ply main body 26a and folded around each core 20 from the axial inside toward the outside.

[0039] The second carcass ply 28 includes: a second ply main body 28a spanned between one core 20 and the other core 20; and a pair of second folded portions 28b connected to the second ply main body 28a and folded around each core 20 from the axial inside to the outside.

[0040] exist Figure 1 , the double arrow HF1 is the radial distance from the bead baseline BLf to the end of the first turn-back portion 26b. The distance HF1 is the height of the first turn-back portion 26b. The double arrow HF2 is the radial distance from the bead baseline BLf to the end of the second turn-back portion 28b. The distance HF2 is the height of the second turn-back portion 28b. In this tire 2, the height HF1 of the first turn-back portion 26b is higher than the height HF2 of the second turn-back portion 28b. The height HF1 of the first turn-back portion 26b may also be lower than the height HF2 of the second turn-back portion 28b.

[0041] exist Figure 2 The structure of the carcass 10 is shown together with the cap band 14 described later. Figure 2 In the figure, 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 is the radial direction of the tire 2. The front side of the paper is the radial outside, and the back side is the radial inside.

[0042] like Figure 2 As shown, each carcass ply 24 constituting the carcass 10 includes a plurality of carcass cords 30 arranged in parallel. Figure 2 In FIG. 1 , for convenience of explanation, the carcass cords 30 are indicated by solid lines, but the carcass cords 30 are covered with a topping rubber 32 .

[0043] Each carcass cord 30 is inclined relative to the equatorial plane. Figure 2 As shown, the inclination direction of the carcass cords 30 in the first carcass ply 26 is opposite to the inclination direction of the carcass cords 30 in the second carcass ply 28. Figure 2 , the angle θ1f is the angle formed between the carcass cords 30 in the first carcass ply 26 and the equatorial plane. The angle θ2f is the angle formed between the carcass cords 30 in the second carcass ply 28 and the equatorial plane. In this tire 2, the inclination angle θ1f and the inclination angle θ2f are the same.

[0044] In this disclosure, the average of the angles θ1f and θ2f is used as the angle θf formed between the carcass cord 30 and 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 described below is also expressed similarly to that of the tire 2.

[0045] The carcass cords 30 are cords made of organic fibers. Examples of the organic fibers include nylon fibers, rayon fibers, polyester fibers, and aramid fibers.

[0046] The inner liner 12 is located inside the carcass 10 and forms the inner surface of the tire 2. The inner liner 12 is made of a cross-linked rubber having a low gas permeability coefficient and maintains the internal pressure of the tire 2.

[0047] The cap band 14 is located between the tread 4 and the carcass 10 in the radial direction. Figure 1 As shown, a band 14 is laminated to the carcass 10. The position indicated by reference symbol Bf is the end of the band 14. The length indicated by the double-headed 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 this tire 2, the ratio (BWf / TWf) of the width BWf of the band 14 to the tread width TWf is 0.80 or greater and 0.95 or less.

[0048] The cap band 14 includes a helically wound cap band cord 34. Figure 2 For ease of explanation, the band cord 34 is shown as a solid line, but the band cord 34 is covered by a topping rubber 36. In this tire 2, the band cord 34 substantially extends in the circumferential direction. Specifically, the angle formed between the band cord 34 and the circumferential direction is 5° or less. The band 14 is also called a seamless band.

[0049] 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.

[0050] Used in the formation of the crown band 14 Figure 3 The strip 38 is in a belt shape. The strip 38 is composed 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 side by side in its 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 into a spiral shape in the circumferential direction.

[0051] Although not shown, the cross sections of the band 14 included in the meridian cross section of the tire 2 have the cross sections of the plurality of band cords 34 arranged in a row. In other words, the band 14 of the tire 2 is composed of a single band ply.

[0052] In this tire 2, the number of band cords 34 sections per 5 cm of the band 14 cross section, obtained in a 10 cm width region centered on the equatorial plane, in a 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 "number of cords / 5 cm." The density Dr of the band cords of the rear tire, described below, is also expressed in the same manner as in this tire 2.

[0053] In the tire 2, the density Df of the band cords 34 in the band 14 is preferably 30 cords / 5 cm or more to ensure air leakage resistance. The density Df of the band cords 34 is preferably 50 cords / 5 cm or less to reduce weight.

[0054] [Rear tire]

[0055] Figure 4 FIG. 5 shows a portion of a meridian cross section of a rear tire 52 (hereinafter referred to as tire 52). Figure 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 . Figure 4 The direction perpendicular to the paper is the circumferential direction of the tire 52. Figure 4 In FIG, the one-dot chain line ELr is the equatorial plane of the tire 52 .

[0056] exist Figure 4 In FIG, a solid line BLr extending in the axial direction is a bead base line. The bead base line BLr is a line that defines the rim diameter (see JATMA, etc.) of a rim (not shown) on which the tire 52 is mounted.

[0057] 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 cap band 64 .

[0058] The tread 54 is made of cross-linked rubber. Its tread surface 66 contacts the road surface. In a meridian cross-section, the tread surface 66 is curved so that its equatorial portion protrudes radially outward. Grooves 68 are engraved on the tread 54, thereby forming a tread pattern. The tread 54 may or may not have grooves 68.

[0059] exist Figure 4 , the position shown by reference numeral Re is the end of the tread surface 66. The length shown by the double arrow TWr is the tread width. Even in this tire 52, the end Re of the tread surface 66 is the axial outer end of the tire 52.

[0060] Each sidewall 56 is made of cross-linked rubber and is connected to the end of the tread 54. The sidewall 56 is located radially inward of the tread 54. The sidewall 56 extends radially along the carcass 60.

[0061] Each bead 58 is radially located inward of the sidewall 56. Each bead 58 includes a core 70 and an apex 72. Although not shown, the core 70 is made of a steel wire rod. The apex 72 is radially located outward of the core 70. The apex 72 tapers toward the outer tip. The apex 72 is made of highly rigid cross-linked rubber.

[0062] The carcass 60 is located inside the tread 54 and the pair of sidewalls 56. The carcass 60 is spanned between one bead 58 and the other bead 58. The tread 54 is located outside the carcass 60 in the radial direction.

[0063] The carcass 60 includes at least one carcass ply 74. The carcass 60 of the tire 52 is composed of two carcass plies 74, namely, a first carcass ply 76 and a second carcass ply 78.

[0064] The first carcass ply 76 includes a first ply main body 76 a spanned between one core 70 and the other core 70 ; and a pair of first folded portions 76 b connected to the first ply main body 76 a and folded around each core 70 from the axial inside to the outside.

[0065] The second carcass ply 78 includes: a second ply main body 78a which is spanned between one core 70 and the other core 70; and a pair of second folded portions 78b which are connected to the second ply main body 78a and folded around each core 70 from the axial inside to the outside.

[0066] exist Figure 1 In the figure, the double-headed arrow HR1 indicates the height of the first turn-back portion 76b. The double-headed arrow HR2 indicates the height of the second turn-back portion 78b. In this tire 52, the height HR1 of the first turn-back portion 76b is higher than the height HR2 of the second turn-back portion 78b. The height HR1 of the first turn-back portion 76b may also be lower than the height HR2 of the second turn-back portion 78b.

[0067] exist Figure 5 The structure of the carcass 60 is shown together with the cap band 64 described later. Figure 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 is the radial direction of the tire 52. The front side of the paper is the radial outer side, and the back side is the radial inner side.

[0068] like Figure 5 As shown, each carcass ply 74 includes a plurality of carcass cords 80 arranged in parallel. Figure 5In FIG. 8 , for convenience of explanation, the carcass cords 80 are also indicated by solid lines, but the carcass cords 80 are covered with a topping rubber 82 .

[0069] Each carcass cord 80 is inclined relative to the equatorial plane. Figure 5 As shown, the inclination direction of the carcass cords 80 in the first carcass ply 76 is opposite to the inclination direction of the carcass cords 80 in the second carcass ply 78. Figure 5 , the angle θ1r is the angle formed between the carcass cords 80 in the first carcass ply 76 and the equatorial plane. The angle θ2r is the angle formed between the carcass cords 80 in the second carcass ply 78 and the equatorial plane. In this tire 52, the inclination angle θ1r and the inclination angle θ2r are the same.

[0070] In the tire 52, the carcass cords 80 are cords made of organic fibers. Examples of the organic fibers include nylon fibers, rayon fibers, polyester fibers, and aramid fibers.

[0071] The inner liner 62 is located inside the carcass 60. The inner liner 62 forms the inner surface of the tire 52. The inner liner 62 is made of a cross-linked rubber having a low gas permeability coefficient. The inner liner 62 maintains the internal pressure of the tire 52.

[0072] The cap band 64 is located radially between the tread 54 and the carcass 60. Figure 4 As shown, a cap band 64 is laminated on the carcass 60. Like the cap band 14 of the front tire 2, the cap band 64 is composed of a single cap band ply.

[0073] exist Figure 4 , the position indicated by reference symbol Br is the end of the band 64. The length indicated by 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 0.80 or more and 0.95 or less.

[0074] The cap band 64 includes a helically wound cap band cord 84. Figure 5 In the figure, for ease of explanation, the band cord 84 is also indicated by a solid line, but the band cord 84 is covered by a topping rubber 86. In this tire 52, the band cord 84 substantially extends in the circumferential direction. Specifically, the angle formed between the band cord 84 and the circumferential direction is 5° or less.

[0075] 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.

[0076] Although not shown, a strip is used to form the cap band 64, similar to the cap band 14 of the front tire 2. Although not described in detail, the cap band 64 is formed by spirally winding a strip in the circumferential direction.

[0077] In the tire 52, the density Dr of the band cords 84 in the band 64 is preferably 30 cords / 5 cm or more to ensure air leakage resistance. The density Dr of the band cords 84 is preferably 50 cords / 5 cm or less to reduce weight.

[0078] [Tire pair]

[0079] The present inventors conducted intensive research with the goal of improving the ride comfort of motorcycles and found that focusing on the bending stiffness of band cords is effective for improving ride comfort and that the bending stiffness of band cords contributes to ensuring stability, thereby completing the present invention.

[0080] In this disclosure, the bending stiffness of a band cord is the average of the bending moment at +15 degrees and the bending moment at -15 degrees. The unit of bending stiffness is g·cm, and the bending stiffness is expressed with the value rounded off to the second decimal place. If the bending stiffness of a band cord is too low to measure, the bending stiffness of the band cord is expressed as 0.0 g·cm. The bending moments at +15 degrees and -15 degrees are measured as follows using a stiffness tester (e.g., Model 150-D) manufactured by Taber Corporation (USA).

[0081] A band cord (length = 145 mm) was sampled from the band of the tire.

[0082] like Figure 6 As shown, the band cord ( Figure 6 The two ends of the label B) are installed on the fixture ( Figure 6 Label K).

[0083] The other jig K was moved relative to one jig K to give the band cord B bending angles of +15 degrees and -15 degrees.

[0084] The bending moment when a bending angle of +15 degrees was applied was obtained as the bending moment at +15 degrees, and the bending moment when a bending angle of -15 degrees was applied was obtained as the bending moment at -15 degrees.

[0085] In a tire, a band cord with low flexural rigidity contributes to improved ride comfort. If the flexural rigidity of the band cord is too low, the tire will deform significantly when a high load is applied. A tire with this large deformation can reduce stability.

[0086] In a two-wheeled vehicle, the rear wheel side of the vehicle body is structurally heavier than the front wheel side. During high-speed driving, lift forces act, further increasing the weight on the rear wheel side. Therefore, the band cord of the rear tire attached to the rear wheel must have a certain level of flexural rigidity.

[0087] Thus, even if the bending rigidity of the band cord is adjusted in the tire alone, it is difficult to adjust the ride comfort and stability in a balanced manner.

[0088] Therefore, the inventors conducted in-depth research focusing on the fact that the front tires contribute more to ride comfort and the rear tires contribute more to stability. They found that by using a band cord with low bending stiffness in the front tire and a band cord with high bending stiffness in the rear tire as a tire pair, ride comfort and stability can be adjusted in a balanced manner. They also found that when the ratio of the bending stiffness of the band cord of the front tire to the bending stiffness of the band cord of the rear tire is set to 0.7 or more, ride comfort is reduced due to the front tire, and stability is reduced due to the rear tire.

[0089] That is, in this tire pair, the ratio (Jf / Jr) of the bending stiffness Jf of the band cord 34 of the front tire 2 to the bending stiffness Jr of the band cord 84 of the rear tire 52 is 0.0 or greater and less than 0.7. In this tire pair, the front tire 2 contributes to improved ride comfort, while the rear tire 52 contributes to ensured stability. This tire pair, consisting of the front tire 2 and the rear tire 52, achieves excellent ride comfort and stability. This tire pair achieves improved ride comfort and ensured stability, which cannot be achieved by adjusting the band cords of a single tire.

[0090] In this tire pair, the bending rigidity Jf of the band cord 34 of the front tire 2 is preferably less than 15.0 g·cm, and the bending rigidity Jr of the band cord 84 of the rear tire 52 is preferably 15.0 g·cm to 40.0 g·cm.

[0091] By setting the bending rigidity Jf of the band cord 34 of the front tire 2 to less than 15.0 g·cm, a reduction in ride comfort caused by the front tire 2 is suppressed. From this perspective, a bending rigidity Jf of 10.0 g·cm or less is more preferable. From the perspective of ride comfort, a lower bending rigidity Jf is better, so there is no preferred lower limit for the bending rigidity Jf.

[0092] By setting the flexural rigidity Jr of the band cord 84 of the rear tire 52 to 15.0 g·cm or greater, a decrease in stability caused by the rear tire 52 is suppressed. Furthermore, by setting the flexural rigidity Jr to 40.0 g·cm or less, a decrease in ride comfort caused by the rear tire 52 is suppressed. From this perspective, the flexural rigidity Jr is more preferably 30 g·cm or less.

[0093] From the perspective of achieving good ride comfort and stability, the bending rigidity Jf of the band cord 34 of the front tire 2 is more preferably 10.0 g·cm or less, and the bending rigidity Jr of the band cord 84 of the rear tire 52 is more preferably 15.0 g·cm or more and 30.0 g·cm or less.

[0094] As mentioned above, the band cord 34 of the front tire 2 is composed of either steel cord or organic fiber. The band cord 34 is designed to have a low flexural rigidity Jf. Therefore, when using steel cord as the band cord 34, a thinner steel cord is used. In this case, the strength of the band cord 34 is reduced, and the front tire 2's water pressure burst strength may not meet the required standards. If the band cord 34 is composed of organic fibers other than aramid fiber, the restraining force of the band 14 is insufficient, potentially reducing high-speed stability. To prevent a decrease in water pressure burst strength and high-speed stability caused by the band 14, the band cord 34 of the front tire 2 in this tire pair is preferably composed of aramid fiber. Furthermore, by confirming the tire's water pressure burst strength, it is possible to assess the tire's durability when overfilled with air.

[0095] As described above, the band cord 84 of the rear tire 52 is composed of steel cords or organic fibers. Because the band cord 84 has a high flexural rigidity Jr, when using an organic fiber cord as the band cord 84, a thicker diameter organic fiber cord is used. In this case, the proportion of the band cord 84 in the band 64 increases, and the amount of topping rubber 86 covering the band cord 84 decreases. If the band cord 84 is not covered with a sufficient amount of topping rubber 86, the topping rubber 86 is likely to peel from the band cord 84, potentially reducing the durability of the rear tire 52. To prevent a decrease in durability caused by the band 64, the band cord 84 of the rear tire 52 in this tire pair is preferably a steel cord.

[0096] In this tire pair, since the band cord 34 having a low bending rigidity Jf is used in the band 14 of the front tire 2, the stress of the front tire 2 at a slip angle is reduced. Depending on the degree of stress reduction, cornering performance may be impaired.

[0097] 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. Because the smaller inclination angle θf increases the stress of the front tire 2 when it is subjected to a slip angle, the turning force of the front tire 2 is higher than that of the rear tire 52. In this tire pair, despite the use of the band cord 34 with a lower flexural rigidity Jf in the cap band 14 of the front tire 2, the turning performance of the motorcycle is improved. From this perspective, the inclination angle θf of the carcass cord 30 of the front tire 2 is preferably 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 greater, more preferably 8° or greater. This difference (θr - θf) is preferably 25° or less, more preferably 20° or less.

[0098] In this tire pair, the inclination angle θf of the carcass cord 30 of the front tire 2 is 20° or more and less than 70°, and the inclination angle θr of the carcass cord 80 of the rear tire 52 is preferably 70° or more.

[0099] By setting the inclination angle θf to 20° or greater, the rigidity of the carcass 10 in the front tire 2 is appropriately maintained, thereby maintaining good ride comfort. From this perspective, the inclination angle θf is more preferably 30° or greater, and even more preferably 40° or greater. Furthermore, by setting the inclination angle θf to less than 70°, the carcass 10 contributes to improved cornering performance. From this perspective, the inclination angle θf is more preferably 68° or less, and even more preferably 65° or less.

[0100] By setting the tilt angle θr to 70° or greater, the rigidity of the carcass 60 in the rear tire 52 is appropriately maintained. By balancing the contributions of the rear tire 52 to turning performance with those of the front tire 2, the motorcycle maintains excellent agility. This tire pair effectively contributes to improved turning performance. From this perspective, the tilt angle θr is more preferably 72° or greater, and even more preferably 80° or greater. The upper limit of the tilt angle θr is 90°.

[0101] The density of the cap cords in the cap band affects the stress generated when the tire is subjected to slip angles. The higher the density of the cap cords, the greater the stress generated when the tire is subjected to slip angles. Greater stress contributes to improved cornering force.

[0102] 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 cornering force of the front tire 2 is higher than that of the rear tire 52. In this tire pair, even though the band cord 34 having a lower flexural rigidity Jf is used in the band 14 of the front tire 2, the turning performance of the motorcycle is improved. From this perspective, the density Df of the band cord 34 in the band 14 of the front tire 2 is preferably 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 greater, and more preferably 1.2 or greater. From the viewpoint of adjusting the rigidity of the front tire 2 and the rigidity of the rear tire 52 in a balanced manner, the ratio (Df / Dr) is preferably 1.4 or less, and more preferably 1.3 or less.

[0103] As described above, according to the present invention, a pair of motorcycle tires that can contribute to improving riding comfort and ensuring stability can be obtained.

[0104] [Example]

[0105] Hereinafter, the present invention will be described in further detail with reference to Examples and the like, but the present invention is not limited to these Examples.

[0106] [Example 1]

[0107] A pair of tires for a two-wheeled vehicle is obtained, which consists of a front tire (120 / 70ZR17) and a rear tire (180 / 55ZR17). The front tire (120 / 70ZR17) has Figure 1 The basic structure shown in Table 1 below has the following specifications. The rear tire (180 / 55ZR17) has Figure 4 The basic structure is shown in FIG. 1 and has the specifications shown in Table 1 below.

[0108] In the front tire of Example 1, the band cord used was made of aramid fiber. This is indicated as "K" in the band cord column F of Table 1. The bending rigidity Jf and density Df of the band cord, as well as the inclination angle θf of the carcass cord, are shown in Table 1 below.

[0109] In this front tire, carcass cords made of rayon fibers are used. The carcass cord structure is 1840 dtex / 2. The height HF1 of the first folded portion is 45 mm, and the height HF2 of the second folded portion is 20 mm.

[0110] In the rear tire of Example 1, steel cords were used as band cords. This is indicated as "S" in the band cord column R of Table 1. The bending rigidity Jr and density Dr of the band cords and the inclination angle θr of the carcass cords are shown in Table 1 below.

[0111] This rear tire uses a carcass cord made of rayon fiber. The carcass cord structure is 1840 dtex / 2. The height HR1 of the first turn-up is 50 mm, and the height HR2 of the second turn-up is 30 mm.

[0112] [Example 2]

[0113] A tire pair of Example 2 was obtained in the same manner as in Example 1 except that the inclination angle θr of the carcass cord of the rear tire was set as shown in Table 1 below.

[0114] [Example 3]

[0115] A tire pair of Example 3 was obtained in the same manner as in Example 2 except that the inclination angle θf of the carcass cord of the front tire was set as shown in Table 1 below.

[0116] [Example 4]

[0117] 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.

[0118] [Examples 5-10 and Comparative Examples 1-3]

[0119] Tire pairs of Examples 5 to 10 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1 except that the specifications of the band cords of the front tire and the band cords of the rear tire were as shown in Tables 1 and 2 below.

[0120] [Handling stability]

[0121] The front tire was mounted on a rim (MT3.50×17), and the tire was filled with air to adjust the internal pressure to 250 kPa. The rear tire was mounted on a rim (MT5.50×17), and the tire was filled with air to adjust the internal pressure to 290 kPa.

[0122] The front and rear tires were mounted on a large two-wheeled vehicle (displacement = 1300cc). The two-wheeled vehicle was driven on a test track on a dry asphalt pavement, and the ride comfort, stability, and cornering performance were evaluated by test riders (on a 5-point scale). The results are presented as indices in Tables 1 and 2 below. The total value of the index for each item is recorded in the column for handling stability in Tables 1 and 2. The larger the value, the better.

[0123] Durability

[0124] The prototype tire (rear tire) was run on a drum tester under the following conditions. The broken state of each cord and the peeling state of each component after running were visually confirmed. The results are expressed as indices in Tables 1 and 2 below. A larger value indicates superior tire durability.

[0125] Rim: MT5.50×17

[0126] Internal pressure: 235kPa

[0127] Speed: 80km / h

[0128] Longitudinal load: 4.41kN

[0129] Driving distance: 16,000 km

[0130] [Water pressure breaking strength]

[0131] A prototype tire (front tire) was assembled onto a rim (MT3.50×17). Water was then filled into the tire to increase the internal pressure, causing the tire to collapse. The pressure at which the tire collapsed was measured. The results are presented as an index in Tables 1 and 2 below. A larger index indicates a higher water pressure collapse strength.

[0132]

Table 1

[0133]

[0134]

Table 2

[0135]

[0136] As shown in Table 1-2, it was confirmed that the tire pair of the embodiment can contribute to the improvement of ride comfort and the assurance of stability. The superiority of the present invention is obvious from the evaluation results.

[0137] Industrial applicability

[0138] The technology described above that can contribute to improving ride comfort and ensuring stability can also be applied to tire pairs for various motorcycles.

Claims

1. A tire pair for a two-wheeled motor vehicle, comprising a front tire and a rear tire, wherein: The front tire and the rear tire each have: a pair of tire beads; A carcass, which is mounted between the tire beads on one side and the tire beads on the other side; a tread located radially outside the carcass; and a cap band located radially between the tread and the carcass, The carcass comprises a plurality of carcass cords arranged in parallel, each carcass cord being inclined relative to the equatorial plane. The band includes a band cord extending substantially in the circumferential direction, wherein the angle formed between the band cord and the circumferential direction is 5° or less. 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 0.0 or more and less than 0.7, and the bending rigidity of the band cord is an average value of the bending moment at +15 degrees and the bending moment at -15 degrees. The bending rigidity of the band cord of the front tire is less than 15.0 g·cm, The flexural rigidity of the band cord of the rear tire is 15.0 g·cm or more and 40.0 g·cm or less, An angle formed between the carcass cords of the front tire and the equatorial plane is smaller than an angle formed between the carcass cords of the rear tire and the equatorial plane.

2. The tire pair for a two-wheeled vehicle according to claim 1, wherein: The cap cord of the front tire is a cord made of aramid fiber. The band cords of the rear tire are steel cords.

3. The tire pair for a motorcycle according to claim 1 or 2, wherein: The angle between the carcass cords of the front tire and the equatorial plane is greater than 20° and less than 70°. The angle formed between the carcass cords of the rear tire and the equatorial plane is greater than 70°.

4. The tire pair for a motorcycle according to claim 1 or 2, wherein: The density of the band cords in the band of the front tire is higher than the density of the band cords in the band of the rear tire.

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