JP2009143332A - Tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire 2 for a motorcycle having excellent straight line stability and turning stability. <P>SOLUTION: This tire 2 is provided with a pair of beads 8, a carcass 10, a band 12 positioned on the outer side in the radial direction of the carcass 10 and a reinforcement layer 14 laminated on the band 12. The band 12 includes a band cord spirally wound and substantially extended to the circumferential direction. The reinforcement layer 14 includes reinforcement cords inclined to the equatorial plane. The reinforcement cords are extended to the circumferential direction while being folded back right and left alternately at both ends 32 of the reinforcement layer 14. The absolute value of the gradient angle of the reinforcement cord is 30-60°. The density of the reinforcement cord is 15-25 ends/5 cm. The reinforcement cord is formed by twining two yarns comprising aramid fibers. The fineness of the yarn is 400-900 dtex. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motorcycle tire.

  Recent motorcycles have high performance and can run at high speed. A two-wheeled vehicle can travel straight at a high speed and turn at a high speed. Further improvement in running performance is desired for tires mounted on the two-wheeled vehicle.

  There is a radial tire with a jointless band. The band has a cord wound spirally and extending substantially circumferentially. This band can contribute to straight running stability at high speeds. However, since this tire is inferior in rigidity, handling is heavy. This tire is inferior in exercise performance. Since this band cannot contribute to the generation of cornering power, this tire also has poor turning performance.

  From the viewpoint of improving tire performance, there is a tire in which a reinforcing layer is laminated on the band. The reinforcing layer includes an inner ply and an outer ply laminated on the inner ply. The inner ply and the outer ply include reinforcing cords that extend at an angle with respect to the equator plane. This reinforcing layer can contribute to the tire rigidity. The handling of this tire is light. With this tire, the exercise performance is improved.

A radial tire for a two-wheeled vehicle with improved high-speed stability and durability is disclosed in JP-A-5-319017. In this tire, a belt layer is provided between the tread and the carcass. The belt layer includes a ply piece formed by inclining a belt-like body including a plurality of cords arranged in parallel with each other and alternately folding back and circulating the belt.
JP-A-5-319017

  In the tire including the reinforcing layer, the end of the reinforcing cord included in the reinforcing layer is located in the vicinity of the end of the tread. In this tire, there is a problem that strain concentrates on the end of the reinforcing layer and looseness occurs.

  In the tire of the above publication, the belt-like body is folded at the end of the belt layer. In this tire, the concentration of distortion at the end of the belt layer can be suppressed. In this tire, the occurrence of looseness is suppressed. However, in this tire, for example, a cord whose material is aramid fiber and whose fineness is 1500 d (denier) / 3 is used for the cord included in the belt layer. In the belt layer having such a cord, it is difficult to precisely control the rigidity of the tire. In this tire, sufficient straight running stability and turning stability cannot be obtained.

  An object of the present invention is to provide a tire for a two-wheeled vehicle that is excellent in straight running stability and turning stability.

  A two-wheeled vehicle tire according to the present invention includes a pair of beads, a carcass spanned between both beads, a band positioned radially outward of the carcass, and a reinforcing layer laminated on the band. . This band includes a band cord wound spirally and extending substantially in the circumferential direction. The reinforcing layer includes a reinforcing cord that is inclined with respect to the equator plane. The reinforcing cord extends in the circumferential direction while being alternately folded back at the both ends of the reinforcing layer. The absolute value of the inclination angle of the reinforcing cord is 30 ° or more and 60 ° or less. The density of the reinforcing cord is 15 ends / 5 cm or more and 25 ends / 5 cm or less. This reinforcing cord is formed by twisting two yarns made of aramid fibers. The fineness of this yarn is not less than 400 dtex and not more than 900 dtex.

  Preferably, in this tire, the band cord is formed by twisting two or three yarns made of aramid fibers. The fineness of this yarn is 1400 dtex. The number of twists of the band cord is 19.5 times / 10 cm or more and 29.5 times / 10 cm or less.

  Preferably, in this tire, the carcass includes a plurality of carcass cords arranged in parallel. This carcass cord is made of rayon fiber, aramid fiber or nylon fiber.

  In this tire, the band includes a band cord wound in a spiral shape and extending substantially in the circumferential direction. This band can contribute to the radial stiffness of the tire. In this tire, the influence of the centrifugal force acting during traveling is suppressed. This tire is excellent in straight running stability. In this tire, the reinforcing layer includes a reinforcing cord inclined with respect to the equator plane. This reinforcing layer can contribute to the rigidity of the tire. Since this tire can generate a large cornering force, it has excellent turning stability. In this tire, the reinforcing cord is folded at the end of the reinforcing layer. In this tire, the concentration of strain at the end of the reinforcing layer can be suppressed. This tire is excellent in durability since the occurrence of looseness is suppressed. In this tire, since the inclination angle, density, and fineness of the reinforcing cord are appropriately adjusted, the reinforcing layer can appropriately contribute to the rigidity of the tire. This tire is excellent in straight running stability and turning stability.

  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 pneumatic tire 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 tire 2 has a substantially left-right symmetric shape centered on a one-dot chain line CL in FIG. This alternate long and short dash line CL represents the equator plane of the tire 2. This equatorial plane extends in the circumferential direction. The tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a band 12, a reinforcing layer 14, an inner liner 16 and a chafer 18. The tire 2 is a tubeless type. The tire 2 is attached to a two-wheeled vehicle.

  The tread 4 is made of a crosslinked rubber having excellent wear resistance. 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. A groove 22 is carved in the tread surface 20. The groove 22 forms a tread pattern. The groove 22 may not be cut in the tread 4.

  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. 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 is located substantially inward of the sidewall 6 in the radial direction. The bead 8 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 10 includes a ply 28. The ply 28 is spanned between the beads 8 on both sides, and extends along the inside of the tread 4 and the sidewall 6. The ply 28 is folded around the core 24 from the inner side to the outer side in the axial direction. The carcass 10 may be composed of two or more plies 28.

  Although not shown, the ply 28 includes a large number of carcass cords and topping rubbers arranged in parallel. The absolute value of the angle formed by each carcass cord with respect to the equator plane is usually 70 ° to 90 °. In other words, the carcass 10 has a radial structure. The tire 2 provided with such a carcass 10 is referred to as a radial tire 2. 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. From the viewpoint of having a high modulus and excellent versatility, the organic fibers are particularly preferably rayon fibers, aramid fibers, and nylon fibers.

  The band 12 is located outside the carcass 10 in the radial direction. The band 12 is located on the inner side in the radial direction of the tread 4. The band 12 is located between the tread 4 and the carcass 10. The end 30 of the band 12 is located in the vicinity of the end of the tread 4. Although not shown, the band 12 is composed of a band cord and a topping rubber. The band cord extends substantially in the circumferential direction and is wound in a spiral shape. The band 12 has a so-called jointless structure.

  Although not shown, the band cord is formed by twisting a plurality of yarns. This yarn consists of organic fibers. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. From the viewpoint that it can contribute to the rigidity of the tire 2, an aramid fiber is preferable as the organic fiber. The number of yarns constituting one band cord is preferably two or three. The fineness of this yarn is preferably 1400 dtex.

  The reinforcing layer 14 is located on the radially outer side of the carcass 10. The reinforcing layer 14 is located on the inner side in the radial direction of the tread 4. The reinforcing layer 14 is laminated on the band 12. In the tire 2, the reinforcing layer 14 is located on the radially inner side of the band 12. The reinforcing layer 14 may be located on the radially outer side of the band 12. The end 32 of the reinforcing layer 14 is located in the vicinity of the end of the tread 4. In the tire 2, the reinforcing layer 14 extends from the vicinity of one end of the tread 4 to the vicinity of the other end. As shown, the position of the end 32 of the reinforcing layer 14 coincides with the position of the end 30 of the band 12 in the axial direction. The end 32 of the reinforcing layer 14 may be located on the inner side in the axial direction of the end 30 of the band 12. The end 32 of the reinforcing layer 14 may be located outside the end 30 of the band 12 in the axial direction.

  The inner liner 16 is joined to the inner peripheral surface of the carcass 10. The inner liner 16 is made of a crosslinked rubber. For the inner liner 16, rubber having excellent air shielding properties is used. The inner liner 16 serves to maintain the internal pressure of the tire 2.

  The chafer 18 is located in the vicinity of the bead 8. When the tire 2 is assembled into a rim (not shown), the chafer 18 comes into contact with the rim. By this contact, the vicinity of the bead 8 is protected. The chafer 18 is usually made of cloth and rubber impregnated in the cloth. A chafer 18 made of a single rubber may be used.

  FIG. 2 is a cross-sectional perspective view showing a part of the reinforcing layer 14 of the tire 2 of FIG. In FIG. 2, the reinforcing layer 14 located in the vicinity of the equator plane is shown. In FIG. 2, an alternate long and short dash line CL represents the equator plane of the tire 2. The direction indicated by the arrow line A is radially outward. The direction indicated by the double arrow line B is the axial direction. The reinforcing layer 14 includes a reinforcing cord 34 and a topping rubber 36. The reinforcing cord 34 is inclined with respect to the equator plane. As shown in the drawing, the inclination direction of the reinforcing cord 34 located in the radially inner portion (hereinafter referred to as the inner portion 38) of the reinforcing layer 14 and the radially outer portion (hereinafter referred to as the outer portion 40). The direction of inclination of the reinforcing cord 34 is opposite. In other words, the reinforcing cord 34 of the inner portion 38 and the reinforcing cord 34 of the outer portion 40 intersect each other.

  The tire 2 is manufactured as follows. First, the reinforcing cord 34 and the topping rubber 36 are extruded by an extruder to form a ribbon.

  FIG. 3 is a cross-sectional perspective view showing the ribbon 42 used for forming the reinforcing layer 14 of FIG. 2. In FIG. 3, a double arrow line C represents the longitudinal direction of the ribbon 42. A double arrow line D represents the width direction of the ribbon 42. As shown, the ribbon 42 is covered with a topping rubber 36 with a reinforcing cord 34. The reinforcing cord 34 extends in the longitudinal direction of the ribbon 42. The number of reinforcing cords 34 included in the ribbon 42 may be one or two or more. When the ribbon 42 includes a plurality of reinforcing cords 34, these reinforcing cords 34 are arranged in parallel in the width direction. As shown in FIG. 3, the ribbon 42 of the tire 2 includes two reinforcing cords 34 arranged in parallel in the width direction.

  Next, the ribbon 42 is supplied to a former (not shown). Other rubber members are also supplied to the former. Examples of other rubber members include the inner liner 16, the carcass 10, the band 12, the sidewall 6, the tread 4, and the like. In the tire 2, the reinforcing layer 14 is formed by the ribbon 42 after the carcass 10 is formed in the former.

  FIG. 4 is a plan view showing the formation state of the reinforcing layer 14. FIG. 4A shows a part of the carcass 10 formed in the former and a part of the ribbon 42 used for forming the reinforcing layer 14. In FIG. 4A, the alternate long and short dash line CL represents the equator plane of the tire 2. A two-dot chain line EL <b> 1 on the left side of the paper surface represents a portion corresponding to one end of the reinforcing layer 14. The two-dot chain line EL2 on the right side represents a portion corresponding to the other end. The front side of the paper surface corresponds to the radially outer side of the tire 2. In the tire 2, the ribbon 42 is adhered to the carcass 10 while the former is rotated. In FIG. 4, the ribbon 42 extends from the vicinity of the equator plane toward one end side. The ribbon 42 is disposed to be inclined with respect to the equator plane. Next, the ribbon 42 is folded back from the inside to the outside along the two-dot chain line EL1. In other words, the ribbon 42 is folded back from the radially inner side to the radially outer side at a location corresponding to one end of the reinforcing layer 14. In the figure, the portion indicated by S is the winding start portion of the ribbon 42.

  FIG. 4B shows a part of the folded ribbon 42. As shown in the figure, the folded ribbon 42 extends from one end of the reinforcing layer 14 toward the other end. The folded ribbon 42 is also inclined with respect to the equator plane. Next, the ribbon 42 is folded back from the inside to the outside along the two-dot chain line EL2. In other words, the ribbon 42 is folded back from the radially inner side to the radially outer side at a position corresponding to the other end of the reinforcing layer 14.

  FIG. 4C shows a state where the ribbon 42 is further folded. As shown in the figure, the folded ribbon 42 extends from the other end of the reinforcing layer 14 toward one end. The folded ribbon 42 is also inclined with respect to the equator plane. In the tire 2, the ribbon 42 is thus wound in the circumferential direction while being alternately folded back and forth at both ends of the reinforcing layer 14.

  FIG. 4D shows a state where the ribbon 42 is wound. As shown in the drawing, when the ribbon 42 is wound once in the circumferential direction, the ribbon 42 is disposed adjacent to the winding start portion S. Although not shown, when the ribbon 42 is further wound once in the circumferential direction, the ribbon 42 is disposed adjacent to the portion of the ribbon 42 adjacent to the winding start portion S. In this way, each time the ribbon 42 is wound once in the circumferential direction, the position of the ribbon 42 is shifted in the circumferential direction. The winding of the ribbon 42 is continued until the carcass 10 is not exposed at the portion where the reinforcing layer 14 is formed. In the tire 2, the reinforcing layer 14 is formed in this way.

  FIG. 5 is a plan view showing a part of the reinforcing layer 14 formed by winding the ribbon 42. As illustrated, the ribbon 42 constituting the reinforcing layer 14 is inclined with respect to the equator plane. As described above, the reinforcing cord 34 included in the ribbon 42 extends in the longitudinal direction of the ribbon 42. In the tire 2, the reinforcement cord 34 is inclined with respect to the equator plane.

  In the tire 2, the reinforcing layer 14 is formed by circumferentially winding the ribbon 42 while being alternately folded left and right at both ends of the reinforcing layer 14. In the tire 2, the reinforcing cord 34 included in the reinforcing layer 14 extends in the circumferential direction while being alternately folded back at the both ends of the reinforcing layer 14. In other words, in the tire 2, the reinforcing cord 34 extends in the circumferential direction while being folded back in a zigzag shape.

  As illustrated, in the tire 2, the ribbon 42 located on the radially inner side of the reinforcing layer 14 and the ribbon 42 located on the radially outer side intersect with each other. In the tire 2, the crossing of the reinforcing cords 34 as shown in FIG. 2 is formed by the crossing of the ribbons 42.

  In the method for manufacturing the tire 2, following the formation of the reinforcing layer 14, rubber members such as the band 12, the sidewall 6, and the tread 4 are assembled. With this assembly, a low cover (also referred to as an uncrosslinked tire) is obtained. The raw cover is put into a mold and is sandwiched between the cavity surface of the mold and the outer surface of the bladder and is pressed. The raw cover is heated by heat conduction from the bladder and the mold. The rubber composition of the raw cover flows by pressurization and heating. The rubber composition causes a crosslinking reaction by heating, and the tire 2 can be obtained.

  As described above, in the tire 2, the band 12 includes a band cord that is wound spirally and extends substantially in the circumferential direction. The band 12 can contribute to the rigidity of the tire 2 in the radial direction. In the tire 2, the influence of the centrifugal force acting during traveling is suppressed. The tire 2 is excellent in straight running stability.

  In the tire 2, the reinforcing layer 14 includes a reinforcing cord 34 that is inclined with respect to the equator plane. The reinforcing layer 14 can contribute to the rigidity of the tire 2. Since the tire 2 can generate a large cornering force, the tire 2 is excellent in turning stability.

  In the tire 2, since the reinforcing cord 34 is folded back at the end 32 of the reinforcing layer 14, strain concentration on the end 32 of the reinforcing layer 14 can be suppressed. In the tire 2, the occurrence of looseness can be suppressed. The tire 2 is excellent in durability.

  As will be described later, in the tire 2, the inclination angle, fineness, and density of the reinforcing cord 34 are appropriately adjusted. The reinforcing layer 14 can appropriately contribute to the rigidity of the tire 2. The tire 2 is excellent in straight running stability and turning stability.

  In FIG. 2, the arrow line L <b> 1 represents the longitudinal direction of the reinforcing cord 34 included in the outer portion 40 of the reinforcing layer 14. The arrow line L2 represents the longitudinal direction of the reinforcing cord 34 included in the inner portion 38. The angle α represents an angle formed by the longitudinal direction L1 with respect to the equator plane. This angle α is the inclination angle of the reinforcing cord 34 of the outer portion 40. The angle β represents an angle formed by the longitudinal direction L2 with respect to the equator plane. This angle β is the inclination angle of the reinforcing cord 34 of the inner portion 38.

  In the tire 2, the absolute value of the inclination angle α is not less than 30 ° and not more than 60 °. By setting the inclination angle α to 30 ° or more, the reinforcing layer 14 can effectively restrain the carcass 10. The tire 2 is excellent in straight running stability. From this viewpoint, the inclination angle α is preferably 40 ° or more. The reinforcing layer 14 can contribute to the rigidity of the tire 2 by setting the inclination angle α to 60 ° or less. Since the tire 2 can generate a large cornering force, the tire 2 is excellent in turning stability. From this viewpoint, the inclination angle α is preferably 50 ° or less.

  In the tire 2, the absolute value of the inclination angle β is not less than 30 ° and not more than 60 °. By setting the inclination angle β to 30 ° or more, the reinforcing layer 14 can effectively restrain the carcass 10. The tire 2 is excellent in straight running stability. From this viewpoint, the inclination angle β is preferably 40 ° or more. The reinforcing layer 14 can contribute to the rigidity of the tire 2 by setting the inclination angle β to 60 ° or less. Since the tire 2 can generate a large cornering force, the tire 2 is excellent in turning stability. From this viewpoint, the inclination angle β is preferably 50 ° or less. From the viewpoint of workability, the inclination angle β is preferably the same as the inclination angle α.

  Although not shown, in the tire 2, the reinforcing cord 34 is formed by twisting two yarns made of aramid fibers. The modulus of the reinforcing cord 34 is larger than that of a cord made of nylon fiber, polyester fiber or rayon fiber. This reinforcing layer 14 effectively reinforces the tire 2. The reinforcing layer 14 can contribute to the rigidity of the tire 2. The tire 2 can generate a large cornering force. The tire 2 is excellent in turning stability.

  In the tire 2, the fineness of the yarn constituting the reinforcing cord 34 is not less than 400 dtex and not more than 900 dtex. By setting the fineness of the yarn to 400 dtex or more, the reinforcing layer 14 can contribute to the rigidity of the tire 2. Since the tire 2 can generate a large cornering force, the tire 2 is excellent in turning stability. From this viewpoint, the fineness of this yarn is preferably 500 dtex or more. By setting the fineness of the yarn to 900 dtex or less, excessive rigidity of the tire 2 is suppressed. In the tire 2, riding comfort can be maintained. From this viewpoint, the fineness of this yarn is preferably 800 dtex or less.

  In the tire 2, the density of the reinforcing cord 34 is 15 ends / 5 cm or more and 25 ends / 5 cm or less. By setting the density to 15 ends / 5 cm or more, the reinforcing layer 14 can contribute to the rigidity of the tire 2. Since the tire 2 can generate a large cornering force, the tire 2 is excellent in turning stability. By setting the density to 25 ends / 5 cm or less, excessive rigidity of the tire 2 is suppressed. In the tire 2, riding comfort can be maintained. This density is obtained by measuring the number (ends) of the reinforcing cords 34 arranged in parallel per 5 cm width of the reinforcing layer 14 in a cross section perpendicular to the longitudinal direction of the reinforcing cords 34.

  In the tire 2, the number of twists of the band cord included in the band 12 is preferably 19.5 times / 10 cm or more and 29.5 times / 10 cm or less. By setting the number of upper twists to 19.5 times / 10 cm or more, the band 12 including the band cord can contribute to the durability of the tire 2. By setting the number of upper twists to 29.5 times / 10 cm or less, the band 12 including this band cord can contribute to the rigidity of the tire 2. In addition, this number of upper twists is measured according to JIS-L1017.

  In the present invention, the size and angle of 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 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.

  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 radial tire for a motorcycle according to Example 1 having the basic configuration shown in FIG. 1 and the specification shown in Table 2 below was obtained. The tire size is “180 / 55ZR17 MC (73W)”. The reinforcing layer is laminated on the inner side in the radial direction of the band (indicated as “in” in the table). The axial width of the reinforcing layer and the axial width of the band are the same. The reinforcing layer is formed by winding a single ribbon including two reinforcing cords arranged in parallel while being folded back alternately at the left and right sides. The direction of inclination of the reinforcing cord located on the inner side of the reinforcing layer is opposite to the direction of inclination of the reinforcing cord located on the outer side thereof. The absolute value of the inclination angle of the reinforcing cord is 45 ° (degree). The fineness of the reinforcing cord is 600 dtex / 2. The density of this reinforcing cord is 20 ends / 5 cm. This reinforcing cord is made of an aramid fiber. The fineness of the band cord included in the band is 1400 dtex / 3. The number of twists of this band cord is 24.5 times / 10 cm. The carcass cord included in the carcass is made of nylon fiber.

[Comparative Examples 4 to 5 and Examples 5 to 6]
A tire was obtained in the same manner as in Example 1 except that the inclination angle of the reinforcing cord was changed as shown in Table 2 below.

[Comparative Examples 3, 6 and 8 and Examples 4 and 7]
Tires were obtained in the same manner as in Example 1 except that the fineness of the reinforcing cords was as shown in Table 1, Table 2, and Table 3 below.

[Comparative Examples 2 and 7 and Examples 3 and 8]
Tires were obtained in the same manner as in Example 1 except that the density of the reinforcing cords was as shown in Table 1, Table 2, and Table 3 below.

[Example 2]
The tire was formed in the same manner as in Example 1 except that the reinforcing layer was arranged on the outer side in the radial direction of the band (indicated as “out” in the table) and the width of the reinforcing layer was larger than the width of the band. Obtained. The difference between the width of the reinforcing layer and the width of the band is 15 mm.

[Comparative Example 1]
A tire was obtained in the same manner as in Example 1 except that the reinforcing layer was composed of an inner ply and an outer ply laminated on the inner ply. The inner ply and the outer ply include reinforcing cords that extend at an angle with respect to the equator plane. In this reinforcing layer, the reinforcing cord is not folded back at the end. This comparative example 1 is a commercially available conventional tire.

[Real car running evaluation]
A prototype tire was mounted on the rear wheel of a commercially available two-wheeled vehicle (4-cycle) having a displacement of 750 cm ³ . The rim has an MT of 5.50 × 17, and the tire has an internal air pressure of 290 kPa. A commercially available conventional tire is mounted on the front wheel. The tire size of this front wheel is “120 / 70ZR17 MC (58W)”. The rim was MT3.50 × 17, and the tire air pressure was 250 kPa. Sensory evaluation by riders was performed on a circuit course composed of dry asphalt roads. This result is shown as an index value with Comparative Example 1 as 100. Larger values indicate better results. Evaluation items are straight running stability and turning ability. These results are shown in Table 1, Table 2 and Table 3 below.

  As shown in Table 1, the tires of the examples are excellent in straight running stability and turning stability. From this evaluation result, the superiority of the present invention is clear.

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

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 a cross-sectional perspective view showing a part of the reinforcing layer of the tire of FIG. 1. FIG. 3 is a cross-sectional perspective view showing a ribbon used for forming the reinforcing layer of FIG. 2. FIG. 4 is a plan view showing a formation state of the reinforcing layer. FIG. 5 is a plan view showing a part of the reinforcing layer formed by winding the ribbon.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Tire 4 ... Tread 6 ... Side wall 8 ... Bead 10 ... Carcass 12 ... Band 14 ... Reinforcement layer 16 ... Inner liner 18 ... Chafer 20 ... Tread surface 22 ... Groove 24 ... Core 26 ... Apex 28 ... Ply 34 ... Reinforcing cord 36 ... Topping rubber 38 ... Inner part 40 ... Outer part 42 ... Ribbon

Claims (3)

A pair of beads, a carcass bridged between both beads, a band located radially outside of the carcass, and a reinforcing layer laminated on the band,
The band includes a band cord wound spirally and extending substantially circumferentially;
This reinforcing layer includes a reinforcing cord that is inclined with respect to the equator plane,
The reinforcing cord extends in the circumferential direction while being alternately folded back at the both ends of the reinforcing layer,
The absolute value of the inclination angle of the reinforcing cord is 30 ° or more and 60 ° or less,
The density of the reinforcing cord is 15 ends / 5 cm or more and 25 ends / 5 cm or less,
This reinforcing cord is formed by twisting two yarns made of aramid fibers,
A tire for a two-wheeled vehicle in which the fineness of the yarn is 400 dtex or more and 900 dtex or less. The band cord is formed by twisting two or three yarns made of aramid fibers,
The fineness of this yarn is 1400 dtex,
The tire according to claim 1, wherein the number of twists of the band cord is 19.5 times / 10 cm or more and 29.5 times / 10 cm or less. The carcass includes a large number of carcass cords arranged in parallel,
The tire according to claim 1 or 2, wherein the carcass cord is made of rayon fiber, aramid fiber or nylon fiber.

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