JP2009012543A - Tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire pair 2 for a motorcycle superior in cornering performance. <P>SOLUTION: The tire pair 2 comprises a front tire 4, and a rear tire. The front tire 4 and the rear tire are equipped with a carcass 12, and an inner liner 18 extending along the inner side of the carcass 12, respectively. The inner liner 18 is equipped with a center part 34, and a pair of side parts 36. The center part 34 and the side parts 36 comprise cross-linked rubber. In the front tire 4, the hardness of the center part 34 is higher than that of the side parts 36. In the rear tire, the hardness of the center part 34 is lower than that of the side parts.In the tire pair 2, the hardness of the side parts 36 of the front tire 4 and the center part of the rear tire is preferably between 50 or more and 65 or less. The hardness of the center part 34 of the front tire 4 and the side part of the rear tire is preferably between 75 or more and 90 and less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tire pair mounted on a motorcycle. In detail, it is related with the improvement of the inner liner of a tire.

  The motorcycle turns by tilting the motorcycle inward while turning the handle. In the tire of this motorcycle, a cornering force is generated according to the slip angle, and a camber thrust is generated according to the camber angle. The cornering force and the camber thrust can contribute to the centripetal force generated in the tire during turning. Centrifugal force acts on a motorcycle that is turning. When this centripetal force is balanced with this centrifugal force, the motorcycle can turn stably. The cornering force when the slip angle is 1 ° (degree) is referred to as cornering power.

  Recent motorcycles have a high-power engine. The performance improvement of motorcycles is remarkable. Motorcycles can turn at high speeds. A large speed results in a large centrifugal force. In order for a motorcycle to turn stably at a high speed, a tire capable of generating a large centripetal force is demanded.

  A tire is configured by combining a number of members such as treads and sidewalls. The specification and combination of these members have been adjusted, and improvements in tire performance are being studied. Japanese Unexamined Patent Publication No. 7-186609 discloses a pneumatic tire that can reduce the weight of the tire while maintaining steering stability. In this tire, a protective rubber layer is provided in a region from the buttress to the bead of the tire. Thereby, the thickness reduction of the sidewall is achieved.

One of the members constituting the tire is an inner liner. This inner liner plays a role of maintaining the internal pressure of the tire. This inner liner is a crosslinked rubber formed by crosslinking a rubber composition. From the viewpoint of gas shielding properties, halogenated butyl rubber is mainly used as the base rubber of this rubber composition. From the viewpoint of durability, the inner liner is composed of a crosslinked rubber having a small hardness.
JP-A-7-186609

  From the viewpoint of high-speed stability, a band including a cord substantially spirally wound in a circumferential direction is being adopted for a front tire of a motorcycle. When turning a motorcycle with the motorcycle tilted inward, the rigidity of the front tire is higher than that of a conventional front tire having a belt composed of two plies in which the cord is arranged to be inclined with respect to the equator plane. Since this is insufficient, the centripetal force of this front tire is smaller than that of the conventional front tire. For this reason, in the tire pair composed of the front tire and the rear tire, the centripetal force of the front tire is lower than that of the rear tire. In other words, in this tire pair, the balance between the centripetal force of the front tire and that of the rear tire is poor. Such a tire pair has a problem that it is inferior in turning performance as compared with a conventional tire pair including a front tire and a rear tire.

  An object of the present invention is to provide a pair of motorcycle tires having excellent turning performance.

  The motorcycle tire pair according to the present invention includes 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 the two beads and having a radial structure, and an inner liner extending along the inside of the carcass. I have. The inner liner includes a center portion and a pair of side portions. The center part and the side part are made of a crosslinked rubber. In the front tire, the hardness of the center portion is larger than the hardness of the side portion. In the rear tire, the hardness of the center portion is smaller than the hardness of the side portion.

  Preferably, in this tire pair, the hardness of the side portion of the front tire and the center portion of the rear tire is 50 or more and 65 or less.

  Preferably, in the tire pair, the hardness of the center portion of the front tire and the side portion of the rear tire is 75 or more and 90 or less.

  Preferably, in the tire pair, in the front tire, the difference between the hardness of the center portion and the hardness of the side portion is 10 or more.

  Preferably, in the tire pair, in the rear tire, the difference between the hardness of the side portion and the hardness of the center portion is 10 or more.

  Preferably, in this tire pair, the thickness of the inner liner of the front tire is 0.7 mm or more and 1.5 mm.

  Preferably, in this tire pair, the thickness of the inner liner of the rear tire is 0.7 mm or more and 1.5 mm.

  Preferably, in the tire pair, the front tire further includes a band. The band includes a cord that is substantially spirally wound in a circumferential direction.

  In the motorcycle tire pair according to the present invention, the inner liners of the front tire and the rear tire each have an appropriate hardness distribution. In this tire pair, the difference between the centripetal force of the front tire and that of the rear tire is small. In other words, in this tire pair, the balance between the centripetal force of the front tire and that of the rear tire is good. For this reason, this tire pair is excellent in turning performance.

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

  FIG. 1 is a cross-sectional view showing a part of a front tire 4 of a tire pair 2 according to an embodiment of the present invention. In FIG. 1, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. The front tire 4 has a substantially bilaterally symmetric shape with a one-dot chain line CL in FIG. 1 as the center. This alternate long and short dash line CL represents the equator plane of the front tire 4. A solid line BBL represents a bead base line. The front tire 4 includes a tread 6, a sidewall 8, a bead 10, a carcass 12, a belt 14, a band 16, an inner liner 18 and a chafer 20. The front tire 4 is a tubeless type pneumatic tire. The front tire 4 is attached to the front wheel of the motorcycle.

  The tread 6 is made of a crosslinked rubber having excellent wear resistance. The tread 6 has a shape protruding outward in the radial direction. The tread 6 includes a tread surface 22. The tread surface 22 is in contact with the road surface. In addition, a groove may be engraved on the tread surface 22 to form a tread pattern.

  The sidewall 8 extends substantially inward in the radial direction from the end of the tread 6. The sidewall 8 is made of a crosslinked rubber. The sidewall 8 absorbs an impact from the road surface by bending. Further, the sidewall 8 prevents the carcass 12 from being damaged.

  The bead 10 is located substantially inward of the sidewall 8 in the radial direction. The bead 10 includes a core 24 and an apex 26 that extends radially outward from the core 24. The core 24 has a ring shape. The core 24 includes a plurality of non-stretchable wires (typically steel wires). The apex 26 is tapered outward in the radial direction. The apex 26 is made of a highly hard crosslinked rubber.

  The carcass 12 includes a carcass ply 28. The carcass ply 28 is spanned between the beads 10 on both sides, and extends along the inside of the tread 6 and the sidewall 8. The carcass ply 28 is folded around the core 24 from the inner side to the outer side in the axial direction. The carcass 12 may be composed of two or more carcass plies 28.

  Although not shown, the carcass ply 28 includes a plurality of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each cord with respect to the equator plane is 70 ° or more and 90 ° or less. In other words, the carcass 12 has a radial structure. The carcass 12 in which the absolute value of this angle is set to 70 ° or more and 90 ° or less can contribute to steering stability. The cord is usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The belt 14 is located on the radially outer side of the carcass 12. The belt 14 is laminated with the carcass 12. The belt 14 reinforces the carcass 12. The belt 14 includes a belt ply 30. Although not shown, the belt ply 30 is composed of a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the equator plane. The absolute value of the tilt angle is not less than 10 ° and not more than 35 °. A preferred material for the cord is steel. An organic fiber may be used for the cord. The belt 14 may be composed of two belt plies 30.

  The band 16 includes a band ply 32. The band ply 32 covers the belt 14. Although not shown, the band ply 32 is made of a cord and a topping rubber. The cord extends substantially in the circumferential direction and is wound spirally. The band 16 has a so-called jointless structure. Since the belt 14 is restrained by this cord, lifting of the belt 14 is suppressed. The absolute value of the angle formed by this cord with respect to the equator plane is 5 ° or less, particularly 2 ° or less. In the present invention, the direction in which the absolute value of the angle formed with respect to the circumferential direction is 5.0 ° or less is the “substantially circumferential direction”. In the front tire 4, the cord is made of organic fiber or steel. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The inner liner 18 is joined to the inner peripheral surface of the carcass 12. The inner liner 18 extends along the inner side of the carcass 12. The inner liner 18 serves to maintain the internal pressure of the front tire 4.

  In the front tire 4, the inner liner 18 includes a center portion 34 and a pair of side portions 36. As shown in the figure, the center portion 34 is located inside the tread 6 in the radial direction. The center portion 34 is a crosslinked rubber. The side portion 36 extends substantially inward in the radial direction from the center portion 34. The side portion 36 is located on the inner side in the axial direction of the sidewall 8. The side portion 36 is a crosslinked rubber.

  In the front tire 4, the center portion 34 has a hardness higher than that of the side portion 36. As described above, the center portion 34 is located on the inner side in the radial direction of the tread 6, and the side portion 36 is located on the inner side in the axial direction of the sidewall 8. The center portion 34 having a large hardness can suppress deformation of the tread 6 portion of the front tire 4. The hardness of the side portion 36 is the same as that of the inner liner of a conventional front tire. The inner liner 18 composed of the center portion 34 and the side portion 36 has high rigidity, and the ratio of the rigidity of the center portion 34 to the rigidity of the side portion 36 (rigidity ratio) is large. It can contribute to the generation of camber thrust (hereinafter referred to as centripetal force). The front tire 4 can generate a large centripetal force compared to the centripetal force of the conventional front tire.

  As shown in FIG. 1, in the front tire 4, the end 38 of the center portion 34 is located in the vicinity of the end 40 of the tread 6. Thereby, the center part 34 can contribute to the rigidity of the part of the tread 6 effectively, and the side part 36 can contribute to the rigidity of the part of the sidewall 8 effectively. In the front tire 4, the rigidity can be easily controlled by adjusting the hardness of the center portion 34 and the side portion 36.

  In the front tire 4, the center portion 34 preferably has a hardness of 75 or more and 90 or less. By setting the hardness to 75 or more, the center portion 34 can contribute to the generation of centripetal force. In this respect, the hardness is more preferably equal to or greater than 80. By setting the hardness to 90 or less, excessive rigidity due to the center portion 34 can be suppressed. In the front tire 4, durability and riding comfort can be maintained. From this viewpoint, the hardness is more preferably 85 or less.

  In the front tire 4, the side portion 36 preferably has a hardness of 50 or greater and 65 or less. By setting the hardness to 50 or more, the rigidity of the side portion 36 can be appropriately maintained. The side portion 36 can contribute to responsiveness during steering. From this viewpoint, the hardness is more preferably 55 or more. By setting the hardness to 65 or less, excessive rigidity due to the side portion 36 is suppressed. In the front tire 4, the ride comfort can be maintained. In this respect, the hardness is more preferably 60 or less.

  In the front tire 4, the hardness of the center portion 34 and the hardness of the side portion 36 of the inner liner 18 are durometer hardnesses defined in JIS K 6253. This hardness is measured by pressing a type A durometer against the tire at room temperature. Also in the rear tire described later, the hardness of the center portion and the side portion of the inner liner are measured in the same manner as the front tire 4.

  In the front tire 4, from the viewpoint that the inner liner 18 can effectively contribute to the generation of centripetal force, the difference between the hardness of the center portion 34 and the hardness of the side portion 36 is preferably 10 or more, more preferably 20 or more, 30 or more is particularly preferable. From the viewpoint of transient performance, this difference is preferably 40 or less.

  In FIG. 1, the double arrow line TA represents the thickness of the inner liner 18. A double arrow line H <b> 1 represents the height in the radial direction from the bead base line to the end 40 of the tread 6. This radial height H1 is a reference height. A double arrow line H <b> 2 represents the radial height from the bead base line to the end 38 of the center portion 34.

  In the front tire 4, the inner liner 18 preferably has a thickness TA of 0.7 mm or more and 1.5 mm or less. By setting the thickness TA to 0.7 mm or more, the inner liner 18 can effectively contribute to the generation of the centripetal force of the front tire 4. In this respect, the thickness TA is more preferably equal to or greater than 0.8 mm, and particularly preferably equal to or greater than 0.9 mm. By setting the thickness TA to 1.5 mm or less, excessive rigidity due to the inner liner 18 is suppressed. In the front tire 4, the ride comfort can be maintained. In this respect, the thickness TA is more preferably equal to or less than 1.4 mm, and particularly preferably equal to or less than 1.3 mm.

  In the front tire 4, the ratio of the radial height H2 to the reference height H1 is preferably 0.8 or more and 1.2 or less. By setting this ratio to 0.8 or more, excessive rigidity due to the center portion 34 of the inner liner 18 is suppressed. In the front tire 4, the ride comfort can be maintained. From this viewpoint, this ratio is more preferably 0.9 or more. By setting this ratio to 1.2 or less, the center portion 34 can effectively contribute to the generation of the centripetal force of the front tire 4. From this viewpoint, the ratio is more preferably 1.1 or less.

  In the present invention, the dimensions and angles of each member of the front tire 4 and the rear tire described later are measured in a state where the tire 4 is incorporated in a regular rim and the tire 4 is filled with air so as to have a regular internal pressure. At the time of measurement, no load is applied to the tire 4. In the present specification, the normal rim means a rim defined in a standard on which the tire 4 depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In the present specification, the normal internal pressure means an internal pressure defined in a standard on which the tire 4 depends. “Maximum air pressure” in the JATMA standard, “maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, and “INFLATION PRESSURE” in the ETRTO standard are normal internal pressures.

  FIG. 2 is a cross-sectional view showing a part of the rear tire 42 of the tire pair 2 according to the embodiment of the present invention. In FIG. 2, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. The rear tire 42 has a substantially bilaterally symmetric shape with the one-dot chain line CL in FIG. 2 as the center. This alternate long and short dash line CL represents the equator plane of the rear tire 42. A solid line BBL represents a bead base line. The rear tire 42 includes a tread 44, a sidewall 46, a bead 48, a carcass 50, a belt 52, a band 54, an inner liner 56, and a chafer 58. The rear tire 42 is a tubeless type pneumatic tire. The rear tire 42 is attached to the rear wheel of the motorcycle.

  The tread 44 is made of a crosslinked rubber having excellent wear resistance. The tread 44 has a shape protruding outward in the radial direction. The tread 44 includes a tread surface 60. The tread surface 60 is in contact with the road surface. In addition, a groove may be cut in the tread surface 60 to form a tread pattern.

  The sidewall 46 extends substantially inward in the radial direction from the end of the tread 44. The sidewall 46 is made of a crosslinked rubber. The sidewall 46 absorbs an impact from the road surface by bending. Furthermore, the sidewall 46 prevents the carcass 50 from being damaged.

  The bead 48 is located substantially inward of the sidewall 46 in the radial direction. The bead 48 includes a core 62 and an apex 64 that extends radially outward from the core 62. The core 62 has a ring shape. The core 62 includes a plurality of non-stretchable wires (typically steel wires). The apex 64 is tapered outward in the radial direction. The apex 64 is made of a highly hard crosslinked rubber.

  The carcass 50 includes a carcass ply 66. The carcass ply 66 is spanned between the beads 48 on both sides, and extends along the inside of the tread 44 and the sidewall 46. The carcass ply 66 is folded around the core 62 from the inner side to the outer side in the axial direction. The carcass 50 may be composed of two or more carcass plies 66.

  Although not shown, the carcass ply 66 includes a large number of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each cord with respect to the equator plane is 70 ° or more and 90 ° or less. In other words, the carcass 50 has a radial structure. The carcass 50 in which the absolute value of this angle is set to 70 ° or more and 90 ° or less can contribute to steering stability. The cord is usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The belt 52 is located outside the carcass 50 in the radial direction. The belt 52 is laminated with the carcass 50. The belt 52 reinforces the carcass 50. The belt 52 includes a belt ply 68. Although not shown, the belt ply 68 includes a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the equator plane. The absolute value of the tilt angle is not less than 10 ° and not more than 35 °. A preferred material for the cord is steel. An organic fiber may be used for the cord. The belt 52 may be composed of two belt plies 68.

  The band 54 includes a band ply 70. The band ply 70 covers the belt 52. Although not shown, the band ply 70 is composed of a cord and a topping rubber. The cord extends substantially in the circumferential direction and is wound spirally. The band 54 has a so-called jointless structure. Since the belt 52 is restrained by this cord, the lifting of the belt 52 is suppressed. The absolute value of the angle formed by this cord with respect to the equator plane is 5 ° or less, particularly 2 ° or less. In the present invention, the direction in which the absolute value of the angle formed with respect to the circumferential direction is 5.0 ° or less is the “substantially circumferential direction”. In the rear tire 42, the cord is made of organic fiber or steel. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The inner liner 56 is joined to the inner peripheral surface of the carcass 50. The inner liner 56 extends along the inside of the carcass 50. The inner liner 56 plays a role of maintaining the internal pressure of the rear tire 42.

  In the rear tire 42, the inner liner 56 includes a center portion 72 and a pair of side portions 74. As shown in the figure, the center portion 72 is located radially inside the tread 44. The center portion 72 is a crosslinked rubber. The side portion 74 extends substantially inward in the radial direction from the center portion 72. The side portion 74 is located on the inner side in the axial direction of the sidewall 46. The side portion 74 is a crosslinked rubber.

  In the rear tire 42, the hardness of the center portion 72 is smaller than the hardness of the side portion 74. As described above, the center portion 72 is located on the inner side in the radial direction of the tread 44, and the side portion 74 is located on the inner side in the axial direction of the sidewall 46. The side portion 74 having a large hardness can appropriately maintain the rigidity of the rear tire 42. The hardness of the center portion 72 is the same as that of the inner liner of the conventional rear tire. The inner liner 56 including the center portion 72 and the side portion 74 can contribute to stability because the side portion 74 has high rigidity. Since the inner liner 56 has a small rigidity ratio (stiffness ratio) of the center portion 72 with respect to the rigidity of the side portion 74, it suppresses an increase in the camber thrust. For this reason, the inner liner 56 can suppress the occurrence of the centripetal force of the rear tire 42. The centripetal force generated in the rear tire 42 is smaller than the centripetal force generated in the conventional rear tire.

  As shown in FIG. 2, in the rear tire 42, the end 76 of the center portion 72 is located in the vicinity of the end 78 of the tread 44. Accordingly, the center portion 72 can effectively contribute to the rigidity of the tread 44 portion, and the side portion 74 can effectively contribute to the rigidity of the sidewall 46 portion. In the rear tire 42, the rigidity can be easily controlled by adjusting the hardness of the center portion 72 and the side portion 74.

  In the rear tire 42, the center 72 preferably has a hardness of 50 or greater and 65 or less. By setting this hardness to 50 or more, the rigidity under the center portion 72 is suppressed. In the rear tire 42, the rigidity can be appropriately maintained. From this viewpoint, the hardness is more preferably 55 or more. By setting the hardness to 65 or less, the center portion 72 can suppress an increase in cornering power. The center portion 72 can maintain stability and ride comfort. In this respect, the hardness is more preferably 60 or less.

  In the rear tire 42, the side portion 74 preferably has a hardness of 75 or more and 90 or less. By setting the hardness to 75 or more, the side portion 74 can appropriately maintain the rigidity of the rear tire 42. In this respect, the hardness is more preferably equal to or greater than 80. By setting the hardness to 90 or less, excessive rigidity due to the side portion 74 can be suppressed. In the rear tire 42, durability and riding comfort can be maintained. From this viewpoint, the hardness is more preferably 85 or less.

  In the rear tire 42, from the viewpoint that the inner liner 56 effectively suppresses the occurrence of centripetal force, the difference between the hardness of the center portion 72 and the hardness of the side portion 74 is preferably 10 or more, more preferably 20 or more, and 30 or more. Particularly preferred. From the viewpoint of transient performance, this difference is preferably 40 or less.

  In FIG. 2, the double arrow line TB represents the thickness of the inner liner 56. A double arrow line H <b> 3 represents the height in the radial direction from the bead base line to the end 78 of the tread 44. This radial height H3 is a reference height. A double arrow line H <b> 4 represents the radial height from the bead base line to the end 76 of the center portion 72.

  In the rear tire 42, the thickness TB of the inner liner 56 is preferably 0.7 mm or greater and 1.5 mm or less. The inner liner 56 can effectively contribute to the rigidity of the tire 42 by setting the thickness TB to 0.7 mm or more. In this respect, the thickness TB is more preferably equal to or greater than 0.8 mm, and particularly preferably equal to or greater than 0.9 mm. By setting the thickness TB to 1.5 mm or less, excessive rigidity due to the inner liner 56 is suppressed. In the rear tire 42, the riding comfort can be maintained. In this respect, the thickness TB is more preferably equal to or less than 1.4 mm, and particularly preferably equal to or less than 1.3 mm.

  In the rear tire 42, the ratio of the radial height H4 to the reference height H2 is preferably 0.8 or more and 1.2 or less. By setting this ratio to be 0.8 or more, it is possible to suppress excessive rigidity due to the center portion 72 of the inner liner 56. In the tire 42, rigidity can be appropriately maintained. From this viewpoint, this ratio is more preferably 0.9 or more. By setting the ratio to 1.2 or less, the center portion 72 can effectively suppress the occurrence of the centripetal force of the rear tire 42. From this viewpoint, the ratio is more preferably 1.1 or less.

  The tire pair 2 according to the present invention includes the front tire 4 shown in FIG. 1 and the rear tire 42 shown in FIG. As described above, in the tire pair 2, the inner liners 18 and 56 of the front tire 4 and the rear tire 42 have an appropriate hardness distribution. As a result, a larger centripetal force is generated in the front tire 4 than in the conventional front tire, and a smaller centripetal force is generated in the rear tire 42 than in the conventional rear tire. In the tire pair 2, the difference between the centripetal force of the front tire 4 and that of the rear tire 42 is small even though the front tire 4 is provided with a band 54 having a jointless structure. In other words, in the tire pair 2, the balance between the centripetal force of the front tire 4 and that of the rear tire 42 is good. For this reason, this tire pair 2 is excellent in high-speed stability and turning performance.

  In the tire pair 2, the crosslinked rubber constituting the center portion 34 of the front tire 4 and the crosslinked rubber constituting the side portion 74 of the rear tire 42 are formed by crosslinking the same rubber composition. The crosslinked rubber constituting the side portion 36 of the front tire 4 and the crosslinked rubber constituting the center portion 72 of the rear tire 42 are formed by crosslinking the same rubber composition. In the tire pair 2, it is not necessary to prepare separate rubber compositions for the center portion 34 and the side portion 36 of the front tire 4 and the center portion 72 and the side portion 74 of the rear tire 42. In the tire pair 2, an increase in production cost is suppressed.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
A tire pair including a front tire (120 / 70ZR17) having the structure shown in FIG. 1 and a rear tire (190 / 50ZR17) having the structure shown in FIG. 2 was obtained.

  The carcass of the front tire is composed of a carcass ply. The cord of this carcass ply is nylon fiber. The absolute value of the angle formed by this cord with respect to the equator plane is 90 °. The fineness of this cord is 940 dtex / 2. The band has a jointless structure. The cord contained in this band is made of steel. The configuration of this code is “3 × 3 / 0.19”. The absolute value of the angle that this cord makes with the equator plane is substantially zero. The thickness TA of the inner liner is 1.0 mm. This inner liner consists of a center portion and a side portion. The center portion has a hardness Hc of 90, and the side portion has a hardness Hs of 55. The size of the front tire is “120 / 70ZR17”.

  The carcass of the rear tire is composed of a carcass ply. The cord of this carcass ply is nylon fiber. The absolute value of the angle formed by this cord with respect to the equator plane is 90 °. The fineness of this cord is 940 dtex / 2. The band has a jointless structure. The cord contained in this band is made of steel. The configuration of this code is “3 × 3 / 0.19”. The absolute value of the angle that this cord makes with the equator plane is substantially zero. The thickness TB of the inner liner is 1.2 mm. This inner liner consists of a center portion and a side portion. The center portion has a hardness Hc of 55, and the side portion has a hardness Hs of 90. The size of the rear tire is “190 / 50ZR17”.

[Examples 7 to 10]
A tire pair was obtained in the same manner as in Example 1 except that the thickness TA and the thickness TB were as shown in Tables 1 and 2 below.

[Examples 2, 3, 5 and 11]
A tire pair was obtained in the same manner as in Example 1 except that the hardness Hc of the center portion of the front tire and the hardness Hs of the side portion of the rear tire were as shown in Tables 1 and 2 below.

[Example 6]
A tire pair was obtained in the same manner as in Example 1 except that the hardness Hs of the side portion of the front tire and the hardness Hc of the center portion of the rear tire were as shown in Table 1 below.

[Comparative Example 2 and Example 4]
In the same manner as in Example 1, except that the center portion hardness Hc and the side portion hardness Hs of the front tire, the center portion hardness Hc and the side portion hardness Hs of the rear tire are as shown in Tables 1 and 2 below, Got.

[Comparative Example 1]
A tire pair was obtained in the same manner as in Example 1 except that the inner liner of the front tire had a single structure and the inner liner of the rear tire had a single structure. This tire pair is a conventional tire pair.

[Real car evaluation]
The front tire was assembled in a rim of “MT3.50 × 17”, and this front tire was filled with air so that the internal pressure was 250 kPa. The rear tire was assembled in a rim of “MT6.00 × 17”, and this rear tire was filled with air so that the internal pressure was 290 kPa. This tire pair was mounted on a commercially available motorcycle (4 cycles) having a displacement of 750 cm ³ . This motorcycle was run on a circuit course whose road surface is asphalt, and a sensory evaluation on the turning performance by the rider was performed. The results are shown as index values in Tables 1 and 2 below. The larger this value, the better.

[Static evaluation]
The front tire was assembled in a rim of “MT3.50 × 17”, and this front tire was filled with air so that the internal pressure was 250 kPa. The rear tire was assembled in a rim of “MT6.00 × 17”, and this rear tire was filled with air so that the internal pressure was 290 kPa. The tire pair was mounted on a flat belt testing machine, and the camber thrust and cornering power were measured. The load was 1.3 kN and the camber angle was 30 ° (degree). The results are shown in Tables 1 and 2 below.

  As shown in Tables 1 and 2, in the example, the front tire generates a greater centripetal force than the front tire of Comparative Example 1, and the rear tire generates a smaller centripetal force than the rear tire of Comparative Example 1. It was confirmed that the turning performance of this example was superior to the turning performance of Comparative Example 1. From this evaluation result, the superiority of the present invention is clear.

  The motorcycle tire pair according to the present invention can be mounted on various vehicles.

FIG. 1 is a cross-sectional view showing a part of a front tire of a tire pair according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a part of a rear tire of a tire pair according to an embodiment of the present invention.

Explanation of symbols

2 ... Tire pair 4 ... Front tire 6, 44 ... Tread 8, 46 ... Side wall 10, 48 ... Bead 12, 50 ... Carcass 14, 52 ... Belt 16, 54 ... Band 18, 56 ... Inner liner 20, 58 ... Chafer 22, 60 ... Tread surface 24, 62 ... Core 26, 64 ... Apex 28, 66 ... Carcass ply 30, 68 ... Belt ply 32, 70 ... Band ply 34, 72 ... Center part 36, 74 ... Side part 38, 40, 76, 78 ... End 42 ... Rear tire

Claims (8)

(1) A pair of beads, a carcass spanned between both beads, and an inner liner extending along the inside of the carcass,
This carcass has a radial structure,
This inner liner has a center portion and a pair of side portions,
This center part and side part are made of crosslinked rubber,
A front tire having a hardness of the center portion larger than that of the side portion, and (2) a pair of beads, a carcass bridged between both beads, and an inner side of the carcass. With an inner liner,
This carcass has a radial structure,
This inner liner has a center portion and a pair of side portions,
This center part and side part are made of crosslinked rubber,
A pair of motorcycle tires comprising a rear tire in which the hardness of the center portion is smaller than the hardness of the side portion.   The tire pair according to claim 1, wherein the hardness of the side portion of the front tire and the center portion of the rear tire is 50 or more and 65 or less.   The tire pair according to claim 1 or 2, wherein the hardness of the center portion of the front tire and the side portion of the rear tire is 75 or more and 90 or less.   The tire pair according to any one of claims 1 to 3, wherein a difference between the hardness of the center portion and the hardness of the side portion is 10 or more in the front tire.   The tire pair according to any one of claims 1 to 4, wherein, in the rear tire, a difference between the hardness of the side portion and the hardness of the center portion is 10 or more.   The tire pair according to any one of claims 1 to 5, wherein an inner liner of the front tire has a thickness of 0.7 mm or more and 1.5 mm.   The tire pair according to any one of claims 1 to 6, wherein an inner liner of the rear tire has a thickness of 0.7 mm or more and 1.5 mm. The front tire further includes a band,
The tire pair according to any one of claims 1 to 7, wherein the band includes a cord substantially spirally wound in a circumferential direction.

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