JP2013014191A - Tire for two-wheeled vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire for a two-wheeled vehicle superior in abrasion resistance of a divided tread, and superior in various performances.SOLUTION: A center area C of the tread 4 of this tire 2, an intermediate base layer Mb and a shoulder base layer Sb are constituted of first cross-linked rubber R1. An intermediate cap layer Mc is constituted of second cross-linked rubber R2. A shoulder cap layer Sc is constituted of third cross-linked rubber R3. The ratio Tmb/Tm of a thickness Tmb of the intermediate base layer Mb to a thickness Tm of an intermediate area M and the ratio Tsb/Ts of a thickness Tsb of the shoulder base layer Sb to a thickness Ts of a shoulder area S are different. The ratio of a thickness of a layer constituted of rubber being small in a loss tangent out of the shoulder base layer Sb and the shoulder cap layer Sc to the thickness Ts of the shoulder area, is increased more than the ratio of a thickness of a layer constituted of rubber being small in a loss tangent out of the intermediate base layer Mb and the intermediate cap layer Mc to the thickness Tm of the intermediate area M.

Description

  The present invention relates to a pneumatic tire mounted on a two-wheeled vehicle. In particular, the present invention relates to improvements in tire treads.

  Centrifugal force acts on the motorcycle when turning. A two-wheeled vehicle turns by tilting the vehicle body inward while turning the steering wheel. A cornering force is generated in a tire of a motorcycle according to a slip angle. Camber thrust is generated according to the camber angle. The cornering force and the camber thrust balance with this centrifugal force when turning, and the two-wheeled vehicle can turn stably.

  The tire of a two-wheeled vehicle includes a tread having a small curvature radius in order to facilitate turning. When traveling straight, the center region located at the center in the axial direction of the tread is grounded. At the time of turning, the shoulder region located on the tread end side is grounded. Considering the roles of the center region and the shoulder region, tires employing a divided tread are used.

JP-A-2005-271760

  In a tire employing a divided tread, a difference in wear amount tends to occur between the regions of the divided tread. In order to suppress an increase in the difference in the amount of wear, the material of the center region and the shoulder region cannot be greatly different. In selecting a material suitable for each role of the center region and the shoulder region, a difference in the amount of wear between the regions is a restriction.

  It is conceivable to reinforce the tread with a band or a breaker as a method of suppressing this difference in wear while selecting a material suitable for the role of each region. This reinforcement can be expected to suppress the difference in the amount of wear, but the tire productivity is reduced.

  An object of the present invention is to provide a tire for a motorcycle that is excellent in wear resistance of a divided tread and is excellent in various performances.

  The tire for a motorcycle according to the present invention includes a tread. The tread includes a center region located in the center in the axial direction, a pair of intermediate regions located outside the center region in the axial direction, and a pair of shoulder regions located outside the intermediate region in the axial direction. The intermediate region includes an intermediate base layer located on the radially inner side and an intermediate cap layer located on the radially outer side. The shoulder region includes a shoulder base layer located on the radially inner side and a shoulder cap layer located on the radially outer side. The center region, the intermediate base layer, and the shoulder base layer are made of a first crosslinked rubber. This intermediate cap layer is made of a second crosslinked rubber. This shoulder cap layer is made of a third crosslinked rubber. The ratio Tmb / Tm of the intermediate base layer thickness Tmb to the intermediate region thickness Tm is different from the ratio Tsb / Ts of the shoulder base layer thickness Tsb to the shoulder region thickness Ts. The loss tangent of the first crosslinked rubber, the loss tangent of the second crosslinked rubber, and the loss tangent of the third crosslinked rubber are different from each other. The ratio of the thickness of the rubber layer having a small loss tangent between the shoulder base layer and the shoulder cap layer to the thickness Ts of the shoulder region is the ratio of the intermediate base layer and the intermediate cap layer to the thickness Tm of the intermediate region. The loss tangent is made larger than the ratio of the thicknesses of the layers made of rubber.

  Preferably, in this tire, the ratio Tsb / Ts is larger than the ratio Tmb / Tm. The loss tangent tan δ2 of the second crosslinked rubber is larger than the loss tangent tan δ1 of the first crosslinked rubber, and the loss tangent tan δ3 of the third crosslinked rubber is larger than the loss tangent tan δ2. Preferably, the loss tangent tan δ1 of the first crosslinked rubber is 0.20 or more and 0.50 or less, the loss tangent tan δ2 of the second crosslinked rubber is 0.30 or more and 0.60 or less, and the third crosslinked rubber is Loss tangent tan δ3 of 0.40 or more and 0.70 or less.

  Preferably, in this tire, the ratio Tmb / Tm is greater than the ratio Tsb / Ts, the loss tangent tan δ4 of the first crosslinked rubber is greater than the loss tangent tan δ5 of the second crosslinked rubber, and the loss tangent tan δ5 is It is larger than the loss tangent tan δ6 of the third crosslinked rubber. Preferably, the loss tangent tan δ4 of the first crosslinked rubber is 0.40 or more and 0.70 or less, the loss tangent tan δ5 of the second crosslinked rubber is 0.30 or more and 0.60 or less, and the third crosslinked rubber is Loss tangent tan δ6 of 0.20 or more and 0.50 or less.

The two-wheeled vehicle tire pair according to the present invention includes a rear tire and a front tire. The rear tire and the front tire include a tread. The tread includes a center region located in the center in the axial direction, a pair of intermediate regions located outside the center region in the axial direction, and a pair of shoulder regions located outside the intermediate region in the axial direction. The intermediate region includes an intermediate base layer located on the radially inner side and an intermediate cap layer located on the radially outer side. The shoulder region includes a shoulder base layer located on the radially inner side and a shoulder cap layer located on the radially outer side. The center region, the intermediate base layer, and the shoulder base layer are made of a first crosslinked rubber. This intermediate cap layer is made of a second crosslinked rubber. This shoulder cap layer is made of a third crosslinked rubber.
In this rear tire, the ratio Tsb / Ts of the shoulder base layer thickness Tsb to the shoulder region thickness Ts is larger than the ratio Tmb / Tm of the intermediate base layer thickness Tmb to the intermediate region thickness Tm. The loss tangent tan δ2 of one second crosslinked rubber is made larger than the loss tangent tan δ1 of one first crosslinked rubber, and the loss tangent tan δ3 of one third crosslinked rubber is made larger than the loss tangent tan δ2.
In this front tire, the ratio Tmb / Tm of the intermediate base layer thickness Tmb to the intermediate region thickness Tm is larger than the ratio Tsb / Ts of the shoulder base layer thickness Tsb to the shoulder region thickness Ts. The loss tangent tan δ4 of the other first crosslinked rubber is made larger than the loss tangent tan δ5 of the other second crosslinked rubber, and the loss tangent tan δ5 is made larger than the loss tangent tan δ6 of the other third crosslinked rubber.

  In the tire according to the present invention, the material forming the center region, the intermediate region, and the shoulder region of the tread is configured with a material suitable for each role. Although this tire is a tire having a different material from the center region to the shoulder region, it has excellent wear resistance, and the difference in wear amount between the regions is suppressed.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an explanatory view showing a tread of the tire of FIG. FIG. 3 is a cross-sectional view showing a part of a pneumatic tire according to another embodiment of the present invention. FIG. 4 is an explanatory diagram showing the tread of the tire of FIG. 3.

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

  In FIG. 1, the vertical direction is the radial direction, and the horizontal direction is the axial direction. The tire 2 has a substantially symmetrical shape with respect to the alternate long and short dash line CL. This alternate long and short dash line represents the equator plane. The tire 2 includes a tread 4, a sidewall 6, a beat 8, a carcass 10, a band 12, an inner liner 14 and a chafer 16. The tire 2 is a tubeless type pneumatic tire. The tire 2 is attached to the rear wheel of a two-wheeled vehicle. The tire 2 is a rear tire.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 18 that contacts the road surface. A double arrow C in FIG. 1 indicates a center region located at the center in the axial direction. A double-headed arrow M indicates an intermediate region located outside the center region C in the axial direction. A double-headed arrow S indicates a shoulder region located outside the intermediate region in the axial direction. The intermediate region M and the shoulder region S are a pair of regions that are symmetrical with respect to the equator plane of the tire 2. The tread 4 includes a center region C, a pair of intermediate regions M, and a pair of shoulder regions S.

  The intermediate region M includes an intermediate base layer Mb and an intermediate cap layer Mc. The intermediate base layer Mb is located on the radially inner side. The intermediate cap layer Mc is located on the radially outer side. An intermediate cap layer Mc is overlaid on the outer side in the radial direction of the intermediate base layer Mb. The shoulder region S includes a shoulder base layer Sb and a shoulder cap layer Sc. The shoulder base layer Sb is located on the inner side in the radial direction. The shoulder cap layer Sc is located on the radially outer side. A shoulder cap layer Sc is stacked on the outer side in the radial direction of the shoulder base layer Sb.

  The tread 4 is made of a crosslinked rubber composition (crosslinked rubber). The center region C, the intermediate base layer Mb, and the shoulder base layer Sb are made of the first crosslinked rubber R1. The intermediate cap layer Mc is made of the second crosslinked rubber R2. The shoulder cap layer Sc is made of a third crosslinked rubber R3.

  The sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. The sidewall 6 is made of a crosslinked rubber composition. The sidewall 6 absorbs an impact from the road surface by bending. Furthermore, the sidewall 6 prevents the carcass 10 from being damaged.

  The bead 8 extends from the sidewall 6 substantially inward in the radial direction. The bead 8 includes a core 20 and an apex 22 that extends radially outward from the core 20. The apex 22 is tapered outward in the radial direction. The apex 22 is made of a crosslinked rubber composition. The apex 22 has a high hardness.

  The carcass 10 includes a carcass ply 24. The carcass ply 24 extends along the inner surfaces of the tread 4 and the sidewall 6. The carcass ply 24 is folded around the core 20 from the inner side to the outer side in the axial direction.

  Although not shown, the carcass ply 24 includes a cord and a topping rubber. The absolute value of the angle formed by the cord with respect to the equator plane CL is 65 ° to 90 °. In other words, the tire 2 has a radial structure. The cord is made of organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The band 12 is located between the carcass 10 and the tread 4. The band 12 includes a band ply 26. The band ply 26 includes a cord and a topping rubber (not shown). The cord extends substantially in the circumferential direction and is wound spirally. The band 12 has a so-called jointless structure. This band 12 suppresses kickback and shimmy. The tire 2 including the band 12 is excellent in disturbance absorption performance.

  The material of the cord of the band 12 having the jointless structure is steel or organic fiber. Specific examples of the organic fiber include aramid fiber, nylon fiber, polyester fiber, rayon fiber, and polyethylene naphthalate fiber. From the viewpoint of high restraining force and thus high rigidity, the preferred material of the cord is steel or aramid fiber. In particular, steel is preferred.

  The inner liner 14 is joined to the inner peripheral surface of the carcass 10. The inner liner 14 is made of a crosslinked rubber. The inner liner 14 is made of rubber having excellent air shielding properties. The inner liner 14 plays a role of maintaining the internal pressure of the tire 2.

  A two-dot chain line Lm in FIG. 2 indicates a straight line perpendicular to the tread surface 18 in the intermediate region M. A double arrow Tm indicates the thickness of the intermediate region M. A double-headed arrow Tmb indicates the thickness of the intermediate base layer. The thickness Tm and the thickness Tmb are measured in the direction of the two-dot chain line Lm. An alternate long and two short dashes line Ls indicates a straight line perpendicular to the tread surface 18 in the shoulder region S. A double-headed arrow Ts indicates the thickness of the shoulder region S. A double arrow Tsb indicates the thickness of the shoulder base layer. The thickness Ts and the thickness Tsb are measured in the direction of the two-dot chain line Ls. These Tm, Tmb, Ts, and Tsb are measured in the cross section of the tire 2.

  When the motorcycle is traveling straight, the center region C of the tire 2 is mainly grounded. The loss tangent tan δ1 of the crosslinked rubber R1 in the center region is set small. The center region C contributes to improvement in fuel consumption, straight running stability and wear resistance. From this viewpoint, the loss tangent tan δ1 is preferably 0.50 or less, more preferably 0.45 or less, and particularly preferably 0.40 or less. The tire 2 having a large loss tangent tan δ1 is excellent in grip performance. In this respect, the loss tangent tan δ1 is preferably equal to or greater than 0.20, more preferably equal to or greater than 0.25, and particularly preferably equal to or greater than 0.30.

  The tire 2 in which the rubber hardness H1 of the crosslinked rubber R1 in the center region C is large is excellent in straight running stability performance. The tire 2 having a small rubber hardness H1 is excellent in grip performance.

  In the tire 2, the crosslinked rubber R1 preferably contains silica. By containing this silica, the tire 2 is excellent in gripping performance when traveling straight ahead, even though tan δ1 is small. From this viewpoint, the silica is preferably contained in an amount of 20 parts by mass or more, more preferably 40 parts by mass or more, with respect to 100 parts by mass of the base rubber.

  A rubber composition having a large amount of silica has a high viscosity. By reducing the amount of silica, processing of the rubber composition is facilitated. From this viewpoint, the silica is preferably contained in an amount of 100 parts by mass or less, more preferably 80 parts by mass or less, with respect to 100 parts by mass of the base rubber.

  When the motorcycle is turning, the shoulder region S of the tire 2 is mainly grounded. The loss tangent tan δ3 of the crosslinked rubber R3 of the shoulder cap layer Sc is increased. This shoulder region S contributes to an improvement in grip performance during turning. In this respect, the loss tangent tan δ3 is preferably equal to or greater than 0.40, more preferably equal to or greater than 0.45, and particularly preferably equal to or greater than 0.50.

  On the other hand, the tire 2 having a small loss tangent tan δ3 contributes to a good handle cut. In this respect, the loss tangent tan δ3 is preferably equal to or less than 0.70, more preferably equal to or less than 0.65, and particularly preferably equal to or less than 0.60.

  The tire 2 having a small rubber hardness H3 of the crosslinked rubber R3 is excellent in grip performance during turning. On the other hand, the tire 2 in which the rubber hardness H3 of the crosslinked rubber R3 is large contributes to good handle cutting.

  At the time of transition between straight travel and turning, the intermediate region M is mainly grounded. The loss tangent tan δ2 of the crosslinked rubber R2 is larger than the loss tangent tan δ1. The rubber hardness H2 of the crosslinked rubber R2 is smaller than the rubber hardness H1. The intermediate region M contributes to the improvement of grip performance than the center region C. From this viewpoint, the loss tangent tan δ2 is preferably 0.30 or more, more preferably 0.35 or more, and particularly preferably 0.40 or more. The loss tangent tan δ2 of the crosslinked rubber R2 is smaller than the loss tangent tan δ3. The rubber hardness H2 of the crosslinked rubber R2 is greater than the rubber hardness H3. A ground plane having a small loss tangent tan δ has a small energy loss. The intermediate region M contributes to the improvement of fuel consumption than the shoulder region S. From this viewpoint, the loss tangent tan δ2 is preferably 0.60 or less, more preferably 0.55 or less, and particularly preferably 0.50 or less.

  The ratio Tsb / Ts between the thickness Tsb of the shoulder base layer Sb and the thickness Ts of the shoulder region S is larger than the ratio Tmb / Tm between the thickness Tmb of the intermediate base layer Mb and the thickness Tm of the intermediate region M. The shoulder region S has a larger base layer ratio than the intermediate region M. The ratio of the thickness of the shoulder base layer Sb made of rubber having a small loss tangent between the shoulder base layer Sb and the shoulder cap layer Sc to the thickness Ts of the shoulder region S is the intermediate base layer Mb to the thickness Tm of the intermediate region M. And the intermediate cap layer Mc, the loss tangent is made larger than the ratio of the thickness of the intermediate base layer Mb made of rubber. In the shoulder region S, sufficient rigidity can be obtained by the shoulder base layer Sb, so that the loss tangent tan δ3 of the third crosslinked rubber R3 can be increased. In this respect, the ratio Tsb / Ts is preferably equal to or greater than 0.5, and more preferably equal to or greater than 0.7. On the other hand, the ratio Tsb / Ts is preferably 0.9 or less, and more preferably 0.8 or less, from the viewpoint of securing grip performance during turning.

  The tire 2 has a small difference in rigidity between regions. The tire 2 is excellent in wear resistance. A difference in wear amount among the center region C, the intermediate region M, and the shoulder region S hardly occurs. In addition, the discomfort experienced by the rider when the ground contact surface moves between the center region and the shoulder region S is reduced. The tire 2 is excellent in transient characteristics. Since the tire 2 has a large difference in wear amount and a decrease in transient characteristics, the materials of the crosslinked rubber R1 to the crosslinked rubber R3 can be made suitable for each role.

  A two-wheeled vehicle using the tire 2 as a rear tire can achieve both straight traveling and turning performance.

  Although not shown, in the manufacture of the tire 2, the inner liner 14 and the carcass ply 24 are sequentially wound around the former. A ribbon made of a cord and a topping rubber is spirally wound on the carcass ply 24 to form a band ply 26 having a jointless structure. The ribbon extends substantially in the circumferential direction.

  On the band ply 26, a first strip made of uncrosslinked rubber is spirally wound. The first strip extends substantially in the circumferential direction. The first strips are laminated sequentially. When the first strip is wound, a third strip made of uncrosslinked rubber is wound continuously with the first strip. The third strip extends substantially in the circumferential direction. The third strip is sequentially laminated. When the third strip is finished, the second strip is further wound continuously with the third strip. A green tire is thus obtained. In addition, the winding method from the first strip to the third strip, the winding order of each strip, and the winding thickness can be appropriately adjusted according to the configuration of the tread described above.

  This green tire is put into a mold, and pressurized and heated. A cross-linking reaction occurs in the rubber by heating, and the tire 2 is obtained. A first crosslinked rubber R1 is obtained from the first strip. A third cross-linked rubber R3 is obtained from the third strip. A second crosslinked rubber R2 is obtained from the second strip. In the tire 2, since three types of strips are used and wound sequentially, the center region C, the intermediate base layer Mb, and the shoulder base layer Sb are easily formed. The intermediate cap layer Mc and the shoulder cap layer Sc are easily formed. The tread 4 can be easily manufactured by a strip wind method.

  The tire 2 does not require reinforcement such as a band or a breaker in order to compensate for a decrease in rigidity of the shoulder region S. The ratio Tsb / Ts and the ratio Tmb / Tm can be easily adjusted by the strip wind method. The tire 2 is excellent in productivity by using a strip wind method.

  In this invention, the rubber hardness is measured by pressing a type A durometer against the tire 2 under the condition of 23 ° C. in accordance with the provisions of “JIS-K 6253”.

The loss tangent tan δ is measured by a viscoelastic spectrometer (trade name “VA-200”, manufactured by Shimadzu Corporation) under the conditions shown below in accordance with the provisions of “JIS-K 6394”.
Initial strain: 10%
Amplitude: ± 2%
Frequency: 10Hz
Deformation mode: Tensile Measurement temperature: 70 ° C

  In the present invention, unless otherwise specified, the dimensions and angles of the respective members of the tire 2 are measured in a state where the tire 2 is incorporated in a regular rim and the tire 2 is filled with air so as to have a regular internal pressure. At the time of measurement, no load is applied to the tire 2. In the present specification, the normal rim means a rim defined in a standard on which the tire 2 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 2 relies. “Maximum air pressure” in JATMA standard, “Maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in TRA standard, and “INFLATION PRESSURE” in ETRTO standard are normal internal pressures.

  FIG. 3 shows a tire 28 according to another embodiment of the present invention. Here, the configuration different from the tire 2 is mainly described, and the description of the same configuration is omitted. The tire 28 includes a tread 30, a sidewall 32, a bead 34, a carcass 36, a band 38, an inner liner 40, and a chafer 42. The tire 28 is a tubeless type pneumatic tire. The tire 28 is attached to the front wheel of a two-wheeled vehicle. The tire 28 is a front tire.

  The tread 30 forms a tread surface 44 that contacts the road surface. The tread 30 includes a center region C, a pair of intermediate regions M, and a pair of shoulder regions S. The intermediate region M includes an intermediate base layer Mb and an intermediate cap layer Mc. The shoulder region S includes a shoulder base layer Sb and a shoulder cap layer Sc.

  The center region C, the intermediate base layer Mb, and the shoulder base layer Ms are made of the first crosslinked rubber R4. The intermediate cap layer Mc is made of the second crosslinked rubber R5. The shoulder cap layer Sc is made of a third crosslinked rubber R6.

  In the tire 28, the loss tangent tan δ4 of the first crosslinked rubber R4 is larger than the loss tangent tan δ5 of the second crosslinked rubber R5. The rubber hardness H4 of the first crosslinked rubber R4 is smaller than the rubber hardness H5 of the second crosslinked rubber R5. The loss tangent tan δ5 of the second crosslinked rubber R5 is larger than the loss tangent tan δ6 of the third crosslinked rubber R6. The rubber hardness H5 of the second crosslinked rubber R5 is smaller than the rubber hardness H6 of the third crosslinked rubber R6.

  When the motorcycle is traveling straight, the center region C of the tire 28 is mainly grounded. The loss tangent tan δ4 of the crosslinked rubber R4 in the center region C is increased. This center region C contributes to the improvement of the disturbance absorbing performance when traveling straight. In this respect, the loss tangent tan δ4 is preferably equal to or greater than 0.40, more preferably equal to or greater than 0.45, and particularly preferably equal to or greater than 0.50.

  On the other hand, the tire 28 having a small loss tangent tan δ4 is excellent in straight running stability and wear resistance. In this respect, the loss tangent tan δ4 is preferably equal to or less than 0.70, more preferably equal to or less than 0.65, and particularly preferably equal to or less than 0.60.

  When the motorcycle is turning, the shoulder region S of the tire 28 is mainly grounded. The loss tangent tan δ6 of the crosslinked rubber R6 of the shoulder cap layer Sc is set small. This shoulder region S contributes to the generation of a large camber thrust. From this viewpoint, the loss tangent tan δ6 is preferably 0.50 or less, more preferably 0.45 or less, and particularly preferably 0.40 or less. In particular, in the tire 28, since the disturbance absorption performance is obtained by the shoulder base layer Sb, the loss tangent tan δ6 can be set smaller than that of the conventional tire.

  On the other hand, the tire 28 having a large loss tangent tan δ6 contributes to an improvement in grip performance. In this respect, the loss tangent tan δ6 is preferably equal to or greater than 0.20, more preferably equal to or greater than 0.25, and particularly preferably equal to or greater than 0.30.

  At the time of transition between straight travel and turning, the intermediate region M is mainly grounded. The loss tangent tan δ5 of the crosslinked rubber R5 of the intermediate cap layer Mc is smaller than the loss tangent tan δ4. This intermediate region M can generate a larger camber thrust than the center region C. In this respect, the loss tangent tan δ5 is preferably equal to or less than 0.60, more preferably equal to or less than 0.55, and particularly preferably equal to or less than 0.50. The loss tangent tan δ5 of the crosslinked rubber R5 is larger than the loss tangent tan δ6. The intermediate region M contributes to the improvement of disturbance absorption performance than the shoulder region S. From this viewpoint, the loss tangent tan δ5 is preferably 0.30 or more, more preferably 0.35 or more, and particularly preferably 0.40 or more.

  The ratio Tsb / Ts between the thickness Tsb of the shoulder base layer Sb and the thickness Ts of the shoulder region S is smaller than the ratio Tmb / Tm between the thickness Tmb of the intermediate base layer Mb and the thickness Tm of the intermediate region M. The shoulder region S has a base layer ratio smaller than that of the intermediate region M. The ratio of the thickness of the shoulder cap layer Sc made of rubber having a small loss tangent of the shoulder base layer Sb and the shoulder cap layer Sc to the thickness Ts of the shoulder region S is the intermediate base layer Mb to the thickness Tm of the intermediate region M. The intermediate cap layer Mc has a smaller loss tangent than the thickness ratio of the intermediate cap layer Mc made of rubber. Since the cross-linked rubber R6 in the shoulder region is thickened, a large camber thrust is easily obtained. In this respect, the ratio Tsb / Ts is preferably equal to or less than 0.5, and more preferably equal to or less than 0.3.

  On the other hand, the tire 28 having a large base layer ratio in the shoulder region S is excellent in disturbance absorption performance and transient characteristics. In this respect, the ratio Tsb / Ts is preferably equal to or greater than 0.1, and more preferably equal to or greater than 0.2.

  The loss tangent tan δ5 of the second crosslinked rubber R5 is smaller than the loss tangent tan δ4 of the first crosslinked rubber R4. The rubber hardness H5 of the second crosslinked rubber R5 is greater than the rubber hardness H4 of the first crosslinked rubber R4. The center region C is more suitable for improving disturbance absorbing performance than the intermediate region M. On the other hand, in the intermediate region M, a larger camber thrust than the center region C is likely to occur.

  The loss tangent tan δ6 of the third crosslinked rubber R6 is smaller than the loss tangent tan δ5 of the second crosslinked rubber R5. The rubber hardness H6 of the third crosslinked rubber R6 is greater than the rubber hardness H5 of the second crosslinked rubber R5. This intermediate region M is more suitable for improving disturbance absorbing performance than the shoulder region S. On the other hand, a larger camber thrust than that in the intermediate region M is likely to occur in the shoulder region S.

  In the tire 28, the center region C having a low hardness is mainly grounded when traveling straight. This tire 28 is excellent in disturbance absorbing performance. Steering stability when going straight is improved. The shoulder region S with high hardness is mainly grounded during turning. A large camber thrust is likely to occur in the shoulder region S. The tire 28 is excellent in turning stability. A two-wheeled vehicle using the tire 28 as a front tire can achieve both straight traveling and turning performance.

  Since the tire 28 includes the intermediate base layer Mb and the shoulder base layer Sb, the characteristics of the tire 28 gradually change at the time of transition between the straight traveling and the turning traveling, and the discomfort of the rider is reduced. The tire 28 has excellent transient characteristics at the time of transition between straight traveling and turning traveling.

  By using the tire 2 described above as a rear tire and using the tire 28 as a front tire, the two-wheeled vehicle can exhibit more straight running performance and turning performance.

  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 rear tire of Example 1 having the structure shown in FIG. 1 was obtained. In this tire, the rubber hardness H1 of the first crosslinked rubber, the rubber hardness H2 of the second crosslinked rubber, and the rubber hardness H3 of the third crosslinked rubber, the loss tangent tan δ1 of the first crosslinked rubber, the loss tangent tan δ2 of the second crosslinked rubber, and The loss tangent tan δ3 of the second crosslinked rubber is as shown in Table 1. The size of the rear tire is “190 / 55ZR17”.

[Comparative Example 1]
Comparative Example 1 is a tire having the same structure as that of Example 1 except that the center region, the intermediate region, and the shoulder region each include a divided tread made of a single crosslinked rubber. The rubber hardness and loss tangent tan δ are as shown in Table 1. Here, the hardness of the crosslinked rubber in the center region is described as H1, and the loss tangent is described as tan δ1. Similarly, the hardness of the crosslinked rubber in the middle region is described as H2, the loss tangent is tan δ2, the hardness of the crosslinked rubber in the shoulder region is H3, and the loss tangent is described as tan δ3.

[Examples 2 to 4]
A rear tire was obtained in the same manner as in Example 1 except that the rubber hardness and loss tangent of the first crosslinked rubber, the second crosslinked rubber, and the third crosslinked rubber were set as shown in Table 1.

[Examples 5 to 11]
A rear tire was obtained in the same manner as in Example 1 except that the ratio Tsb / Ts of the shoulder region and the ratio Tmb / Tm of the intermediate region were as shown in Table 2.

[Example 12]
A front tire of Example 12 having the structure shown in FIG. 3 was obtained. In this tire, rubber hardness H4 of the first crosslinked rubber, rubber hardness H5 of the second crosslinked rubber, rubber hardness H6 of the third crosslinked rubber, loss tangent tan δ4 of the first crosslinked rubber, loss tangent tan δ5 of the second crosslinked rubber, and The loss tangent tan δ6 of the second crosslinked rubber is as shown in Table 1. The size of the front tire is “125 / 80R17”.

[Comparative Example 2]
Comparative Example 2 is a tire having the same structure as Example 12 except that the center region, the intermediate region, and the shoulder region each include a divided tread having a single tread. The rubber hardness and loss tangent tan δ are as shown in Table 3. Here, the hardness of the crosslinked rubber in the center region is described as H4, and the loss tangent is described as tan δ4. Similarly, the hardness of the crosslinked rubber in the intermediate region is H5 and the loss tangent is tan δ5, the hardness of the crosslinked rubber in the shoulder region is H6, and the loss tangent is tan δ6.

[Examples 13 to 15]
A front tire was obtained in the same manner as in Example 12 except that the rubber hardness and loss tangent of the first crosslinked rubber, the second crosslinked rubber, and the third crosslinked rubber were changed as shown in Table 3.

[Examples 16 to 22]
A front tire was obtained in the same manner as in Example 12 except that the shoulder region ratio Tsb / Ts and the intermediate region ratio Tmb / Tm were as shown in Table 4.

[Grip performance and transient characteristics]
A prototype rear tire was mounted on the rear wheel of a commercially available two-wheeled vehicle having a displacement of 1000 cc. The rim width was 6 inches and the tire air pressure was 250 kPa. The front wheel tire was a commercially available tire. The motorcycle was run on a test course, and the rider was given a sensory evaluation of grip performance and transient characteristics. The results are shown in Tables 1 and 2 below. This evaluation is evaluated on a 10-point scale, and the higher the number, the higher the evaluation.

[Abrasion resistance evaluation]
The two-wheeled vehicle equipped with the prototype rear tire was run over a distance of 1000 km on the test course. The amount of wear was determined before and after traveling, and the wear index (tread thickness after traveling / tread thickness before traveling) was determined from this amount of wear. Relative evaluation was performed with the tire of Comparative Example 1 as 100. The results are shown in Table 1 below. The higher the index, the less wear.

[Maneuvering stability and transient characteristics]
A prototype front tire was mounted on the front wheel of a commercially available two-wheeled vehicle having a displacement of 1000 cc. The rim width was 3.50 inches and the tire internal pressure was 200 kPa. As the rear wheel tire, a commercially available tire was used as it was. The motorcycle was run on a test course, and the rider was given a sensory evaluation of steering stability and transient characteristics. The results are shown in Tables 3 and 4 below. This evaluation is evaluated on a 10-point scale, and the higher the number, the higher the evaluation.

[Abrasion resistance evaluation]
The motorcycle equipped with the prototype front tire was run at a distance of 1000 km on the test course. The amount of wear was determined before and after traveling, and the wear index (tread thickness after traveling / tread thickness before traveling) was determined from this amount of wear. Relative evaluation was performed with the tire of Comparative Example 2 as 100. The results are shown in Table 1 below. The higher the index, the less wear.

  From the evaluation results in Tables 1 to 4, the superiority of the present invention is clear.

  The tire according to the present invention can be mounted on various motorcycles.

2, 28 ... Tire 4, 30 ... Tread 6, 32 ... Sidewall 8, 34 ... Bead 10, 36 ... Carcass 12, 38 ... Band 14, 40 ... Inner Liner 16, 42 ... Chafer 18, 44 ... Tread surface 20 ... Core 22 ... Apex 24 ... Carcass ply 26 ... Band ply

Claims (6)

With a tread,
The tread includes a center region positioned in the center in the axial direction, a pair of intermediate regions positioned outside in the axial direction of the center region, and a pair of shoulder regions positioned outside in the axial direction of the intermediate region,
The intermediate region includes an intermediate base layer positioned radially inside and an intermediate cap layer positioned radially outward, and the shoulder base layer positioned radially outward and a shoulder cap positioned radially outward With layers,
The center region, the intermediate base layer, and the shoulder base layer are made of a first crosslinked rubber, the intermediate cap layer is made of a second crosslinked rubber, the shoulder cap layer is made of a third crosslinked rubber,
The ratio Tmb / Tm of the thickness Tmb of the intermediate base layer to the thickness Tm of the intermediate region is different from the ratio Tsb / Ts of the thickness Tsb of the shoulder base layer to the thickness Ts of the shoulder region,
The loss tangent of the first crosslinked rubber, the loss tangent of the second crosslinked rubber, and the loss tangent of the third crosslinked rubber are different from each other,
The ratio of the thickness of the rubber layer having a small loss tangent between the shoulder base layer and the shoulder cap layer to the thickness Ts of the shoulder region is the ratio of the intermediate base layer and the intermediate cap layer to the thickness Tm of the intermediate region. A tire for a two-wheeled vehicle having a larger loss ratio than a ratio of thicknesses of layers made of rubber. The ratio Tsb / Ts is larger than the ratio Tmb / Tm,
The tire according to claim 1, wherein the loss tangent tan δ2 of the second crosslinked rubber is larger than the loss tangent tan δ1 of the first crosslinked rubber, and the loss tangent tan δ3 of the third crosslinked rubber is larger than the loss tangent tan δ2. The loss tangent tan δ1 of the first crosslinked rubber is 0.20 or more and 0.50 or less,
The loss tangent tan δ2 of the second crosslinked rubber is 0.30 or more and 0.60 or less,
The tire according to claim 2, wherein the loss tangent tan δ3 of the third crosslinked rubber is 0.40 or more and 0.70 or less. The ratio Tmb / Tm is larger than the ratio Tsb / Ts,
The tire according to claim 1, wherein the loss tangent tan δ4 of the first crosslinked rubber is larger than the loss tangent tan δ5 of the second crosslinked rubber, and the loss tangent tan δ5 is larger than the loss tangent tan δ6 of the third crosslinked rubber. The loss tangent tan δ4 of the first crosslinked rubber is 0.40 or more and 0.70 or less,
The loss tangent tan δ5 of the second crosslinked rubber is 0.30 or more and 0.60 or less,
The tire according to claim 4, wherein a loss tangent tan δ6 of the third crosslinked rubber is 0.20 or more and 0.50 or less. It has a rear tire and a front tire,
This rear tire and front tire are equipped with treads,
The tread includes a center region positioned in the center in the axial direction, a pair of intermediate regions positioned outside in the axial direction of the center region, and a pair of shoulder regions positioned outside in the axial direction of the intermediate region,
The intermediate region includes an intermediate base layer positioned radially inward and an intermediate cap layer positioned radially outward, and the shoulder region has a shoulder base layer positioned radially inward and a shoulder positioned radially outward. With a cap layer,
The center region, the intermediate base layer, and the shoulder base layer are made of a first crosslinked rubber, the intermediate cap layer is made of a second crosslinked rubber, the shoulder cap layer is made of a third crosslinked rubber,
In this rear tire, the ratio Tsb / Ts of the shoulder base layer thickness Tsb to the shoulder region thickness Ts is larger than the ratio Tmb / Tm of the intermediate base layer thickness Tmb to the intermediate region thickness Tm. The loss tangent tan δ2 of the two crosslinked rubbers is made larger than the loss tangent tan δ1 of the first crosslinked rubber, and the loss tangent tan δ3 of the one third crosslinked rubber is made larger than the loss tangent tan δ2.
In this front tire, the ratio Tmb / Tm of the thickness Tmb of the intermediate base layer to the thickness Tm of the intermediate region is larger than the ratio Tsb / Ts of the thickness Tsb of the shoulder base layer to the thickness Ts of the shoulder region. A pair of tires for a two-wheeled vehicle in which the loss tangent tan δ4 of one crosslinked rubber is larger than the loss tangent tan δ5 of another second crosslinked rubber, and the loss tangent tan δ5 is larger than the loss tangent tan δ6 of another third crosslinked rubber.

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