JP2017052451A - Tire for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire for a motorcycle which realizes excellent turning performance and ride comfort.SOLUTION: In a tire 2, a carcass 10 is composed of one carcass ply 26. An end 32 of a belt 14 is located at the radial outer side of a maximum width position PC of the carcass 10. The belt 14 has no overlapping portion with a folded-back part 30. An apex 24 extends to the radial outer side of the position PC. The radial height from a bead base line to a tip of the apex 24 is 1.20 times or less of the radial height from the bead base line to an end 36 of a tread. In a radial direction, the position of a tip 40 of the apex 24 and the position of a tip 38 of the folded-back part 30 are not the same. A length LB from an equatorial plane to the end 32 of the belt 14 is equal to or longer than a length LD from the equatorial plane to the end of the band.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a motorcycle tire.

  When the motorcycle turns, the rider tilts the motorcycle inward. When running on a circuit with the vehicle body greatly inclined, a strong lateral force is applied to the tire side. The side portion needs to be rigid enough to withstand this strong lateral force. In order to obtain good turning performance, the rigidity of the side portion is increased. On the other hand, increasing the rigidity of the side portion can cause a decrease in ride comfort.

  Japanese Unexamined Patent Publication No. 2013-35540 discloses a tire for a two-wheeled vehicle that achieves both high turning performance and good riding comfort. In this tire, the carcass includes a first carcass ply that is folded around the bead and a second carcass ply that does not have the folded portion. The positions of the end of the folded portion of the first carcass ply and the end of the second carcass ply and the position of the tip of the apex are adjusted appropriately.

JP 2013-35540 A

  Along with the improvement in the performance of motorcycles, further improvements are required in the turning performance and riding comfort of tires. In the tire disclosed in Japanese Patent Laid-Open No. 2013-35540, the carcass includes two carcass plies, so that rigidity may increase. There is room for improvement in the riding comfort of this tire. Further, in this tire, the inner end of the second ply and the tip of the apex may be positioned in the vicinity of the position where the carcass has the maximum width. In this tire, stress tends to concentrate in the vicinity of the maximum width position of the carcass. This can cause buckling of the side portion when a large load is applied during turning. Buckling deteriorates ride comfort and turning performance.

  An object of the present invention is to provide a tire for a two-wheeled vehicle that realizes excellent turning performance and riding comfort.

  A tire for a motorcycle according to the present invention includes a tread, a pair of beads, a carcass spanned between the two beads, a belt laminated outside the carcass, and laminated outside the belt. With a band. The bead includes a core and an apex extending radially outward from the core. The carcass is composed of one carcass ply. The carcass ply is folded around the core from the inner side to the outer side in the axial direction, and the carcass ply forms a main part and a folded part. When the position where the axial width of the carcass is maximized is PC, the end of the belt is positioned radially outside the position PC. The belt does not overlap with the folded portion. The apex extends to the outside in the radial direction of the position PC. The radial height from the bead base line to the tip of the apex is 1.20 times or less the radial height from the bead base line to the end of the tread. In the radial direction, the position of the tip of the apex and the position of the tip of the folded portion are not the same. The length LB from the equatorial plane measured along the outer surface of the belt to the end of the belt is equal to or longer than the length LD from the equatorial plane measured along the outer surface of the band to the end of the band. The ratio (LD / LT) of the length LD to the length LT from the equator plane to the end of the tread measured along the tread surface is 0.75 or more and 0.95 or less.

  Preferably, when the thickness at the midpoint of the apex is WA and the maximum width of the core is WB, the ratio of the thickness WA to the width WB (WA / WB) is 0.30 or more and 0.70 or less. It is.

  Preferably, the apex has a hardness of 70 to 85.

  Preferably, the carcass ply includes a plurality of carcass cords arranged in parallel. The absolute value of the angle formed by each carcass cord with respect to the equator plane is 65 ° or more and 75 ° or less.

  Preferably, the belt includes a plurality of belt cords arranged in parallel. The absolute value of the angle formed by each belt cord with respect to the equator plane is 60 ° or more and 80 ° or less. The inclination direction of the belt cord with respect to the equator plane CL is opposite to the inclination direction of the carcass cord with respect to the equator plane CL.

  The inventors have studied the structure of the side portion for realizing high turning performance and good riding comfort. As a result, it has been found that turning performance and riding comfort can be improved by appropriately adjusting the positions of the belt end, band end, carcass ply turn-up end, and apex tip.

  In this tire, the end of the belt is located radially outside the maximum width position PC of the carcass in the radial direction. This belt does not have an overlapping portion with the folded portion. The length LB from the equatorial plane to the end of the belt is equal to or longer than the length LD from the equatorial plane to the end of the band. In the radial direction, the end of the belt is at the same position as the end of the band, or the end of the belt is located inside the end of the band. That is, the side portion has a portion where none of the belt, the band, and the folded portion exists outside the maximum width position PC of the carcass in the radial direction. Furthermore, the carcass of this tire is composed of one carcass ply. Outside the maximum width position PC of the carcass in the radial direction, the layer having the cord is only one carcass ply. This part contributes to the flexible bending of the side part. In this tire, the ride comfort is improved.

  In this tire, the apex extends radially outward from the maximum width position PC. The radial height from the bead base line to the tip of the apex is 1.20 times or less the radial height from the bead base line to the end of the tread. This apex contributes to the rigidity of the side portion. This side portion has sufficient rigidity to obtain good turning performance. Furthermore, in this tire, the position of the tip of the apex and the position of the tip of the folded portion are not the same in the radial direction. For this reason, the concentration of stress is suppressed. This makes it less likely to buckle at the side. In this tire, the influence on the turning performance and riding comfort due to buckling is suppressed. This tire is excellent in turning performance and ride comfort.

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 enlarged cross-sectional view showing a part of the tire of FIG.

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

  A pneumatic tire 2 shown in FIG. 1 includes a tread 4, a pair of sidewalls 6, a pair of beads 8, a carcass 10, an inner liner 12, a belt 14, and a band 16. A portion of the tire 2 that extends radially inward from the vicinity of the end of the tread 4 is referred to as a side portion 18. The sidewall 6 and the bead 8 are located on the side portion 18. The tire 2 is a tubeless type. The tire 2 is attached to a two-wheeled vehicle. The tire 2 is particularly mounted on the front wheel of a two-wheeled vehicle. 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 tire 2 has a substantially bilaterally symmetric shape with the 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 tire 2.

  The tread 4 is made of a crosslinked rubber. The tread 4 has a shape protruding outward in the radial direction. The tread 4 includes a tread surface 20. The tread surface 20 is in contact with the road surface. Although not shown, a tread pattern may be formed by forming a groove in the tread surface 20.

  Each 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. The sidewall 6 absorbs an impact from the road surface by bending. Furthermore, the sidewall 6 prevents the carcass 10 from being damaged.

  Each bead 8 is positioned substantially inward in the axial direction from the sidewall 6. The bead 8 includes a core 22 and an apex 24 that extends radially outward from the core 22. The core 22 has a ring shape. The core 22 is formed by winding a non-stretchable wire. Typically, a steel wire is used for the core 22. The apex 24 is tapered outward in the radial direction. The apex 24 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a carcass ply 26. The carcass 10 includes a single carcass ply 26. The carcass ply 26 is stretched between the beads 8 on both sides, and extends along the inside of the tread 4 and the sidewall 6. The carcass ply 26 is folded around the core 22 from the inner side to the outer side in the axial direction. By this folding, a main portion 28 and a folding portion 30 are formed in the carcass ply 26.

  Although not shown, the carcass ply 26 includes a large number of carcass cords arranged in parallel and a topping rubber. In this embodiment, the absolute value α of the angle formed by each carcass cord with respect to the equator plane is 65 ° or more and 75 ° or less. The carcass cord is made of an organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The inner liner 12 is located inside the carcass 10. The inner liner 12 is joined to the inner surface of the carcass 10. The inner liner 12 is made of a crosslinked rubber. The inner liner 12 is made of rubber having excellent air shielding properties. A typical base rubber of the inner liner 12 is butyl rubber or halogenated butyl rubber. The inner liner 12 holds the internal pressure of the tire 2.

  The belt 14 is located on the inner side in the radial direction of the tread 4. The belt 14 is laminated with the carcass 10. The belt 14 reinforces the carcass 10. Although not shown, the belt 14 is composed of a number of parallel belt cords and topping rubber. The belt cord is inclined with respect to the equator plane. In this embodiment, the absolute value θ of the tilt angle is not less than 60 ° and not more than 80 °. In the tire 2, the material of the belt cord is an organic fiber. A preferred organic fiber is an aramid fiber. The belt cord may be made of polyester fiber, nylon fiber, rayon fiber and polyethylene naphthalate fiber. The belt cord material may be steel.

  The band 16 is located on the inner side in the radial direction of the tread 4. The band 16 is located on the radially outer side of the belt 14. The band 16 is laminated on the belt 14. Although not shown, the band 16 includes a band cord and a topping rubber. The band cord is spirally wound. The band 16 has a so-called jointless structure. The band cord extends substantially in the circumferential direction. The angle of the band cord with respect to the circumferential direction is 5 ° or less, and further 2 ° or less. The band 16 can contribute to the radial rigidity of the tire 2. The band 16 can suppress the influence of centrifugal force that acts during traveling. The tire 2 is excellent in high speed stability. A preferred material for the band cord is steel. An organic fiber may be used for the band cord. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  In FIG. 1, a double arrow LB is a length from the equator plane measured along the outer surface of the belt 14 to the end 32 of the belt 14. The double arrow LD is the length from the equator plane measured along the outer surface of the band 16 to the end 34 of the band 16. In the tire 2, the length LB is not less than the length LD. That is, the length of the belt 14 is the same as the length of the band 16 or longer than the length of the band 16. In the radial direction, the end 32 of the belt 14 is at the same position as the end 34 of the band 16, or the end 32 of the belt 14 is positioned inside the end 34 of the band 16.

  In FIG. 1, a double arrow LT is the length from the equator plane measured along the tread surface 20 to the end 36 of the tread. In the tire 2, the ratio of the length LD to the length LT (LD / LT) is not less than 0.75 and not more than 0.95.

  FIG. 2 is an enlarged cross-sectional view showing the side portion 18 of the tire 2 of FIG. 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. In FIG. 2, a solid line BBL is a bead base line. The bead base line BBL is a line that defines the rim diameter (see JATMA) of the rim R. The bead base line BBL extends in the axial direction.

  In the figure, reference numeral PC denotes an axially outer end of the main portion 28 of the carcass ply 26. The maximum width of the carcass 10 is defined as an axial distance between one axial outer end of the main portion 28 and the other axial outer end. In other words, the width of the carcass 10 is maximum at the position of the outer end PC. The outer end PC is also referred to as the maximum width position of the carcass 10. A double-pointed arrow HC is a height in the radial direction from the bead base line BBL to the maximum width position PC. A double-headed arrow HB is a radial height from the bead base line BBL to the end 32 of the belt 14. A double-headed arrow HR is a height in the radial direction from the bead base line BBL to the end 38 of the folded portion 30.

  In the tire 2, the end 32 of the belt 14 does not reach the maximum width position PC of the carcass 10. The end 32 of the belt 14 is located radially outward from the maximum width position PC. That is, the height HB is larger than the height HC. In the tire 2, the belt 14 does not have an overlapping portion with the folded portion 30. The end 32 of the belt 14 is located radially outward from the end 38 of the folded portion 30. That is, the height HB is larger than the height HR. As described above, the end 32 of the belt 14 is located at the same position as the end 34 of the band 16 in the radial direction, or the end 32 of the belt 14 is located inside the end 34 of the band 16. The band 16 and the folded portion 30 do not overlap. The tire 2 has a portion where none of the belt 14, the band 16, and the turned-up portion 30 exists outside the maximum width position PC in the radial direction.

  In FIG. 2, the double-headed arrow HA is the radial height from the bead base line BBL to the tip 40 of the apex 24. A double-headed arrow HT is a height in the radial direction from the bead base line BBL to the end of the tread 4.

  In the tire 2, the apex 24 extends to the outside in the radial direction of the position PC. The tip 40 of the apex 24 is located radially outward from the maximum width position PC. That is, the height HA is larger than the height HC. In the tire 2, the radial height from the bead base line to the tip 40 of the apex 24 is 1.20 times or less the radial height from the bead base line to the end of the tread 4. That is, the ratio of the height HA to the height HT (HA / HT) is 1.20 or less.

  Here, the height HB being larger than the height HC means that the ratio (HB / HC) is 1.02 or more. Similarly, the height HB being greater than the height HR means that the ratio (HB / HR) is 1.02 or more. That the height HA is larger than the height HC means that these ratios (HA / HC) are 1.02 or more.

  In the tire 2, the position of the tip 40 of the apex 24 is not the same as the position of the end 38 of the folded portion 30 in the radial direction. That is, the height HA is a value different from the height HR. Here, that the height HA and the height HR are different values means that the ratio (HA / HR) is 0.98 or less or 1.02 or more.

  Hereinafter, the function and effect of the present invention will be described.

  As described above, in the side portion 18 of the tire 2, the height HB of the end 32 of the belt 14 is larger than the maximum width position height HC of the carcass 10 and the height HR of the end 38 of the folded portion 30. The length LB of the belt 14 is longer than the length LD of the band 16. In the radial direction, the end 32 of the belt 14 is at the same position as the end 34 of the band 16, or the end 32 of the belt 14 is positioned inside the end 34 of the band 16. That is, it has a portion where none of the belt 14, the band 16, and the folded portion 30 exists on the radially outer side of the maximum width position of the carcass 10. This portion contributes to the flexible bending of the side portion 18. The side portion 18 can be appropriately bent even during normal running when a high load is not applied to the tire 2 during high-speed turning. In the tire 2, the ride comfort is improved.

  In the tire 2, the carcass 10 is composed of a single carcass ply 26. Compared with the tire 2 configured by two or more carcass plies 26, the rigidity of the side portion 18 is suppressed. Further, as described above, the tire 2 has a portion where none of the belt 14, the band 16, and the turned-up portion 30 exists outside the maximum width position PC of the carcass 10 in the radial direction. In this portion, the layer having the cord is only one carcass ply 26. Due to the combination of the positional relationship of the belt 14, the band 16, and the folded portion 30 and the carcass 10, the side portion 18 can bend more flexibly. In the tire 2, ride comfort is improved. Further, the flexible side portion 18 can lighten the steering. In the tire 2, good steering performance is realized.

  The ratio of height HB to height HC (HB / HC) is preferably 1.05 or more. By setting the ratio (HB / HC) to 1.05 or more, the side portion 18 can bend more flexibly. From this viewpoint, the ratio (HB / HC) is more preferably 1.10 or more. The ratio (HB / HC) is preferably 1.40 or less. By setting the ratio (HB / HC) to 1.40 or less, the rigidity of the side portion 18 is appropriately maintained. The tire 2 has good turning performance. In this respect, the ratio (HB / HC) is more preferably equal to or less than 1.35.

  The ratio of the height HB to the height HR (HB / HR) is preferably 1.10 or more. By setting the ratio (HB / HR) to 1.10 or more, the side portion 18 can bend more flexibly. In this respect, the ratio (HB / HR) is more preferably equal to or greater than 1.15. The ratio (HB / HR) is preferably 1.60 or less. By setting the ratio (HB / HR) to 1.60 or less, the rigidity of the side portion 18 is appropriately maintained. The tire 2 has good turning performance. In this respect, the ratio (HB / HR) is more preferably equal to or less than 1.55.

  In the tire 2, the apex 24 extends outward in the radial direction beyond the maximum width position PC. The height HA of the tip 40 of the apex 24 is larger than the height HC. The apex 24 reinforces the side portion 18 on the radially outer side of the maximum width position PC. The apex 24 contributes to the rigidity of the side portion 18. The tire 2 has rigidity capable of withstanding a large load applied to the side portion 18 even during high-speed turning. The tire 2 is excellent in turning performance. Further, the apex 24 prevents the deflection of the tire 2 from suddenly increasing when a large load is applied. Sudden fluctuations in deflection at the time of transition from straight traveling to turning traveling or from transition to straight traveling (referred to as a transient state) can be suppressed. Deterioration of ride comfort due to sudden fluctuations in deflection is suppressed. The tire 2 is excellent in riding comfort in a transient state. The tire 2 has good transient characteristics.

  The ratio of the height HA to the height HC (HA / HC) is preferably 1.05 or more. By setting the ratio (HB / HC) to 1.05 or more, the apex 24 effectively contributes to the rigidity of the side portion 18. The tire 2 is excellent in turning performance. Further, the apex 24 effectively prevents sudden fluctuations in the bending state. The tire 2 has good transient characteristics. In this respect, the ratio (HA / HC) is more preferably equal to or greater than 1.10.

  In the tire 2, the ratio of the height HA to the height HT (HA / HT) is 1.20 or less. By setting the ratio (HA / HT) to 1.20 or less, the rigidity of the side portion 18 is appropriately maintained. The side portion 18 can flex flexibly. The tire 2 is excellent in ride comfort. Further, in the tire 2, the rigidity of the side portion 18 is increased, thereby preventing the steering from becoming heavy. The tire 2 is excellent in steering performance. In this respect, the ratio (HA / HT) is more preferably 1.10 or less.

  When the positions of the tip 40 of the apex 24 and the end 38 of the folded portion 30 are the same in the radial direction, stress concentration occurs in this portion. Furthermore, the difference in rigidity between the radially inner side and the outer side of this portion increases. When a large load is applied during the turning, the stress concentration and the rigidity difference can cause the side portion 18 to buckle. The buckling of the side portion 18 impairs the turning performance. Furthermore, since the longitudinal spring constant of the tire 2 changes before and after buckling, the riding comfort deteriorates.

  In the tire 2, the position of the tip 40 of the apex 24 is not the same as the position of the end 38 of the folded portion 30 in the radial direction. The height HA is a value different from the height HR. In the tire 2, stress concentration due to the same position of the tip 40 of the apex 24 and the end 38 of the folded portion 30 is suppressed. It is prevented that the difference in rigidity is increased between the radially inner side and the outer side of this portion. In the tire 2, buckling of the side portion 18 is suppressed. The tire 2 is excellent in turning performance and ride comfort.

  The ratio of the height HA to the height HR (HA / HR) is preferably 1.05 or more or 0.95 or less. By setting the ratio (HA / HR) to 1.05 or more or 0.95 or less, stress concentration is effectively suppressed. It is effectively prevented that the rigidity difference is increased between the radially inner side and the outer side of this portion. In the tire 2, buckling of the side portion 18 is suppressed. The tire 2 is excellent in turning performance and ride comfort.

  In the tire 2, the ratio (LD / LT) to the length LT from the equator plane to the tread end 36 with respect to the length LD from the equator plane to the end 34 of the band 16 is 0.75 or more. By setting the ratio (LD / LT) to be 0.75 or more, the band 16 exists in the vicinity of the ground contact surface of the tread 4 even in the case of a full bank. The tread 4 has sufficient rigidity to support a large load during full banking. The tire 2 is excellent in turning performance. Further, in the tire 2, the belt 14 always exists in the vicinity of the ground contact surface in the transient state. This prevents the rigidity of the tread 4 from changing greatly in a transient state. The tire 2 is excellent in riding comfort in a transient state. The tire 2 is excellent in transient characteristics. In this respect, the ratio (LD / LT) is more preferably equal to or greater than 0.80.

  In the tire 2, the ratio (LD / LT) is 0.95 or less. By setting (LD / LT) to 0.95 or less, the influence of the band 16 on the rigidity of the side portion 18 can be suppressed. The side portion 18 has an appropriate rigidity. The side portion 18 can flex flexibly. In the tire 2, good riding comfort and steering performance are realized. In this respect, the ratio (LD / LT) is more preferably equal to or less than 0.90.

  In FIG. 1, a straight line VA is a vertical bisector of a straight line connecting the midpoint of the bottom of the apex 24 and the tip 40 of the apex 24. A point PA is an intersection of the straight line VA and the outer surface of the apex 24. The point PA is referred to as a midpoint of the apex 24. In FIG. 2, a straight line LA is a normal line at the point PA. A double arrow WA is the distance between the outer surface and the inner surface of the apex 24 measured along the normal line LA. A double arrow WA is the thickness at the midpoint PA of the apex 24. A double arrow WB is the maximum width of the core 22.

  The ratio (WA / WB) of the thickness WA to the width WB is preferably 0.30 or more. The apex 24 contributes to the rigidity of the side portion 18 by setting the ratio (WA / WB) to 0.30 or more. The side portion 18 has rigidity capable of withstanding a load during turning. The tire 2 is excellent in turning performance. In this respect, the ratio (WA / WB) is more preferably equal to or greater than 0.35. The ratio (WA / WB) is preferably 0.70 or less. By setting the ratio (WA / WB) to 0.70 or less, the rigidity of the side portion 18 is appropriately maintained. The side portion 18 can flex flexibly. In the tire 2, good riding comfort and steering performance are realized. In this respect, the ratio (WA / WB) is more preferably equal to or less than 0.65.

  The hardness Ah of the apex 24 is preferably 70 or more. The apex 24 contributes to the rigidity of the side portion 18 by setting the hardness Ah to 70 or more. The side portion 18 has rigidity capable of withstanding a load during turning. The tire 2 is excellent in turning performance. In this respect, the hardness Ah is more preferably equal to or greater than 73. The hardness Ah is preferably 85 or less. By setting the hardness Ah to 85 or less, the rigidity of the side portion 18 is appropriately maintained. The side portion 18 can flex flexibly. The tire 2 is excellent in ride comfort. In this respect, the hardness Ah is more preferably equal to or less than 82.

  In the present application, the hardness Ah of the apex 24 is measured by a type A durometer in accordance with the provisions of “JIS K6253”. This durometer is pressed against the cross section shown in FIG. 1, and the hardness is measured. The measurement is made at a temperature of 23 ° C.

  As described above, in the tire 2, the absolute value α of the angle formed by the carcass cord of the carcass ply 26 with respect to the equator plane is preferably 75 ° or less. By setting the absolute value α to 75 ° or less, a sufficient cornering force can be generated in the tire 2. Especially for the front wheels of a two-wheeled vehicle, the tire 2 has a sufficient turning force. The tire 2 is excellent in turning stability. The absolute value α is preferably 65 ° or more. By setting the absolute value α to 65 ° or more, the rigidity of the tread 4 is maintained appropriately. The tire 2 is excellent in ride comfort.

  As described above, in the tire 2, the absolute value θ of the angle formed by the belt cord of the belt 14 with respect to the equator plane is preferably 80 ° or less. By setting the absolute value θ to 80 ° or less, the tread 4 of the tire 2 has sufficient rigidity to withstand lateral force during turning. The tire 2 has a sufficient turning force. The tire 2 is excellent in turning stability. In this respect, the absolute value θ is more preferably 77 ° or less. The absolute value θ is preferably 60 ° or more. By setting the absolute value θ to 60 ° or more, the rigidity of the tread 4 is maintained appropriately. The tire 2 is excellent in ride comfort. In this respect, the absolute value θ is more preferably 70 ° or more.

  The inclination angle of the belt cord is preferably different from the inclination angle of the carcass cord. More preferably, the inclination direction of the belt cord with respect to the equator plane CL is opposite to the inclination direction of the carcass cord with respect to the equator plane CL. The belt 14 effectively tightens the carcass 10 by reversing the inclination direction of the belt cord with respect to the equator plane CL from the inclination direction of the carcass cord with respect to the equator plane CL. The tread 4 of the tire 2 has sufficient rigidity. The tire 2 has a sufficient turning force. The tire 2 is excellent in turning stability.

  In the present invention, the dimensions and angles of the tire 2 and each member 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.

  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 two-wheeled vehicle tire of Example 1 having the structure shown in FIG. 1 was obtained. The tire size was 120 / 70ZR17. Table 1 below shows the specifications of this tire. In the table, among the numbers described in the “Structure” column of “Carcass”, the number on the front side represents the number of carcass plies having folded portions. The number on the back side represents the number of carcass plies that do not have a folded portion. “1-0” in Example 1 indicates that the carcass is composed of one carcass ply having a folded portion.

  In this tire, the height HC of the maximum width position of the carcass is 32 mm. Height HR is shown in the table as a ratio to height HC (HR / HC). The same applies to the height HB and the height HA. At this time, since this tire satisfies the condition (HA> HC), “Yes” is described in the column “Condition (HA> HC)”. The same applies to the condition (HB> HC), the condition (HR ≠ HC), the condition (HB> HR), and the condition (LB ≧ LD). In the following examples and comparative examples, when this condition is not satisfied, “No” is described in this column.

  In this tire, the absolute value of the angle formed by the carcass cord with respect to the equator plane is 72 °. The inclination direction of the belt cord with respect to the equator plane CL is opposite to the inclination direction of the carcass cord with respect to the equator plane CL.

  In this tire, the material of the carcass cord is rayon fiber. The structure of this carcass cord is 1840 dtex / 2. The material of the belt cord is rayon fiber. The structure of this belt cord is 1840 dtex / 2. The material of the band cord is steel. This band cord has a structure in which three strands having an outer diameter of 0.17 mm are twisted and then three strands are twisted.

[Comparative Example 1]
In the tire of Comparative Example 1, the carcass is composed of a carcass ply provided with two folded portions. This is indicated as “2-0” in the “Structure” column of “Carcass”. This tire does not have a belt. This is a conventional tire.

[Comparative Example 2]
In the tire of Comparative Example 2, the carcass is composed of a carcass ply that includes one folded portion and a carcass ply that does not include one folded portion. This is indicated as “1-1” in the “Structure” column of “Carcass”. This tire does not have a belt. This is a conventional tire.

[Comparative Example 3]
The tire of Comparative Example 3 is the same as Comparative Example 2 except that a belt is provided.

[Example 2]
A tire of Example 2 was obtained in the same manner as Example 1 except that the band length was changed and the ratio (LD / LT) was changed as shown in Table 2.

[Example 3, Comparative Example 4-5]
Tires of Example 3 and Comparative Example 4-5 were obtained in the same manner as Example 1 except that the position of the end of the folded portion was changed and the ratio (HR / HC) was as shown in Table 2.

[Comparative Example 6-7]
A tire of Comparative Example 6-7 was obtained in the same manner as in Example 1 except that the length of the belt was changed and the ratio (LB / LT) was changed as shown in Table 2. Since the position of the end of the belt is also changed, the ratio (HB / HC) is also changed.

[Comparative Example 8-9]
The tire of Comparative Example 8-9 was obtained in the same manner as in Example 1 except that the length of the belt and the length of the band were changed and the ratio (LB / LT) and ratio (LD / LT) were changed as shown in Table 3. It was. Since the position of the end of the belt is also changed, the ratio (HB / HC) is also changed.

[Example 4-6]
Tires of Examples 4-6 were obtained in the same manner as Example 1 except that the thickness of the apex was changed and the ratio (WA / WB) was changed as shown in Table 3.

[Comparative Example 10-11]
A tire of Comparative Example 10-11 was obtained in the same manner as in Example 1 except that the tip position of the apex was changed and the ratio (HA / HC) and ratio (HA / HT) were as shown in Table 4.

[Example 7-8]
Tires of Examples 7-8 were obtained in the same manner as in Example 1 except that the hardness of the apex was as shown in Table 4.

[Example 9-10]
Tires of Examples 9-10 were obtained in the same manner as in Example 1 except that the absolute value θ of the belt cord angle was as shown in Table 4.

[Turning stability, steering, transient characteristics, ride comfort]
The prototype tire was assembled in a standard rim (size = MT3.50 × 17) and mounted on the front wheel of a two-wheeled vehicle having a displacement of 1000 cc. The internal pressure of this tire was 250 kPa. A commercially available tire (size: 190 / 50ZR17) was mounted on the rear wheel, and air was filled so that the internal pressure was 290 kPa. This motorcycle was run on a circuit course with asphalt on the road surface, and sensory evaluation was performed by the rider. The evaluation items are turning stability, steering performance (weight when steering), transient characteristics (riding comfort in a transient state), and riding comfort (riding comfort in normal driving). The results are shown in Table 1-4 below, with 5 points being the perfect score. Larger values are preferred.

  As shown in Table 1-4, the tire of the example has a higher evaluation than the tire of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The tire described above can be applied to various two-wheeled vehicles.

2 ... tyre 4 ... tread 6 ... side wall 8 ... bead 10 ... carcass 12 ... inner liner 14 ... belt 16 ... band 18 ... side 20 .. tread surface 22 ... core 24 ... apex 26 ... carcass ply 28 ... main part 30 ... turn-up part 32 ... belt end 34 ... band end 36 ...・ End of tread 38 ... End of folded part 40 ... End of apex

Claims (5)

A tread, a pair of beads, a carcass spanned between the beads, a belt laminated outside the carcass, and a band laminated outside the belt,
The bead includes a core and an apex extending radially outward from the core;
The carcass is composed of one carcass ply,
The carcass ply is folded from the axially inner side to the outer side around the core, and by this folding, a main part and a folded part are formed in the carcass ply,
When the position where the axial width of the carcass is maximized on the outer surface of the carcass is PC,
The end of the belt is located radially outside the position PC,
The belt does not have an overlapping portion with the folded portion,
The apex extends radially outward from the position PC,
The radial height from the bead base line to the tip of the apex is not more than 1.20 times the radial height from the bead base line to the end of the tread;
In the radial direction, the position of the tip of the apex and the position of the end of the folded portion are not the same,
The length LB from the equator plane measured along the outer surface of the belt to the end of the belt is not less than the length LD from the equator plane measured along the outer surface of the band to the end of the band;
A tire for a two-wheeled vehicle, wherein a ratio (LD / LT) of the length LD to a length LT from the equator plane to the end of the tread measured along the tread surface is 0.75 or more and 0.95 or less.   When the thickness at the midpoint of the apex is WA and the maximum width of the core is WB, the ratio of the thickness WA to the width WB (WA / WB) is 0.30 or more and 0.70 or less. 2. The tire for a motorcycle according to 1.   The tire for two-wheeled vehicles according to claim 1 or 2 whose hardness of said apex is 70 or more and 85 or less. The carcass ply includes a large number of carcass cords arranged in parallel,
The tire for a motorcycle according to any one of claims 1 to 3, wherein an absolute value of an angle formed by each carcass cord with respect to the equator plane is 65 ° or more and 75 ° or less. It has a number of belt cords in which the above belts are arranged in parallel.
The absolute value of the angle formed by each belt cord with respect to the equator plane is 60 ° or more and 80 ° or less,
The tire for a motorcycle according to claim 4, wherein an inclination direction of the belt cord with respect to the equator plane CL is opposite to an inclination direction of the carcass cord with respect to the equator plane CL.

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