JP5089259B2 - Pneumatic tires for motorcycles - Google Patents

Description

  The present invention mainly relates to a pneumatic tire mounted on a motorcycle.

  Motorcycles are greatly tilted when turning. For this reason, motorcycle tires are required to have turning stability in addition to straight running stability.

  During cornering, a large load acts on the side portion of the tire. The rigidity of the side part greatly affects the turning stability. The rigidity of the side portion can be adjusted by the number of carcass, the size of the apex rubber, the hardness of the apex rubber, and the like.

JP-A-2004-352226 discloses a motorcycle tire that can contribute to steering stability and turning stability while suppressing an increase in tire mass. The tire carcass includes a first ply and a pair of second plies. The first ply includes an overlapping portion formed by being wound around a bead core of the tire and being folded outward. The second ply is inserted into the overlapping portion and extends a predetermined length along the first ply.
JP 2004-352226 A

  The present inventor has studied improvement of steering stability and the like based on a completely different technical idea from the conventional one. As a result, it has been found that by adopting a completely different structure in the structure of the carcass and the belt, etc., it is possible to achieve improvement in handling stability and shock absorption.

  An object of the present invention is to provide a pneumatic tire for a motorcycle that is excellent in handling stability and shock absorption.

  A pneumatic tire for a motorcycle according to the present invention is spanned between a tread whose outer surface forms a tread surface, a pair of beads positioned radially inward of the tread, and both beads along the inner side of the tread. A carcass and a belt positioned on the inner side in the radial direction of the tread are provided. The carcass includes a first carcass ply spanned between both beads and a second carcass ply located on the outer side in the radial direction of the first carcass ply. The first carcass ply includes a first cord. The first carcass ply includes a main body and a pair of folded portions that are continuous from both ends of the main body. The absolute value of the angle θ1 formed with respect to the equator plane of the first cord is 85 ° or more and 90 ° or less. The second carcass ply includes a second cord. The end of the second carcass is disposed between the folded portion of the first carcass ply and the main body. The absolute value of the intersection angle θ3 between the second cord and the first cord is 30 ° or more and less than 45 ° on the equator plane. The overlap height H1 between the second carcass ply and the folded portion of the first carcass ply is 10 mm or more. The belt includes a first belt ply positioned circumferentially outside the carcass in the circumferential direction and a second belt ply spirally wound substantially circumferentially outside the first belt ply. The first belt ply has a third cord. The third cord is inclined in the opposite direction to the second cord with respect to the equator plane, and the absolute value of the intersection angle θ5 between the third cord and the first cord is 25 ° or greater and 65 ° or less on the equator plane. The second belt ply has a fourth cord.

  Preferably, the second carcass ply and the folded portion are bonded. Preferably, the fourth cord is a steel cord. Preferably, the bead is a cable bead.

  This tire is a so-called radial tire by the first carcass ply. The cord is oriented obliquely by the second carcass ply. Further, the first cord is laminated so as to intersect the second cord at a predetermined angle. With this structure, the in-plane torsional rigidity of the tire is increased. Such a carcass structure enhances steering stability. The end of the second carcass ply is disposed between the main body of the first carcass ply and the folded portion. This second carcass ply is not folded back at the core. This tire has low radial rigidity and excellent shock absorption. The third cord is oriented obliquely at a predetermined angle in the opposite direction to the second cord and the equator plane. The third code intersects the first code at a predetermined angle. This structure increases the rigidity of the tire. In this tire, both steering stability and shock absorption can be achieved.

  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. FIG. 2 is a partially enlarged cross-sectional view showing a part of the tire 2 of FIG. 1 and 2, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. The 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. The tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a belt 12, an inner liner 14, and a chafer 16. The tire 2 is a tubeless type. The tire 2 is attached to a motorcycle.

  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 18. The tread surface 18 is in contact with the road surface. The tread surface 18 does not have a groove. The tread surface 18 may be provided with a groove. When a groove is provided, a tread pattern is formed by the groove.

  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 has a core 20 and an apex 22. The apex 22 extends radially outward from the core 20. The apex 22 is tapered outward in the radial direction. The apex 22 is made of a highly hard crosslinked rubber. The core 20 has a ring shape. The core 20 includes a plurality of non-stretchable wires (typically steel wires). In the embodiment of FIGS. 1 and 2, the cross-sectional shape of the core 20 is substantially rectangular. The bead 8 is a strand bead. Preferably, as the bead 8, a cable bead having a substantially circular cross-sectional shape of the core is used. The core of the cable bead is formed by spirally winding another wire around the core wire. By using the cable bead, the core is easily rotated according to the deformation of the side portion of the tire. As a result, the contact pressure distribution can be easily equalized, and the steering stability can be improved particularly when turning or traveling on rough roads.

  The carcass 10 includes two carcass plies. The carcass 10 includes a first carcass ply 24 and a second carcass ply 26. On the equator plane, the second carcass ply 26 is located radially outside the first carcass ply 24. The first carcass ply 24 and the second carcass ply 26 are along the inside of the tread 4 and the sidewall 6. The first carcass ply 24 and the second carcass ply 26 are in contact with each other. The belt 12 is provided on the outer side in the radial direction of the second carcass ply 26. The second carcass ply 26 is in contact with the belt 12. An inner liner 14 is provided on the radially inner side of the first carcass ply 24. The first carcass ply 24 and the inner liner 14 are in contact with each other.

  The first carcass ply 24 is bridged between the beads 8 on both sides. The first carcass ply 24 is folded around the core 20 from the inner side toward the outer side in the axial direction. The first carcass ply 24 includes a main body 25 and a pair of folded portions 27 that are continuous from both ends of the main body 25. The folded portion 27 extends outward in the radial direction.

  The end 28 of the second carcass ply 26 does not reach the core 20. The second carcass ply 26 is not folded around the core 20. An end 28 of the second carcass ply 26 is disposed between the main body 25 and the folded portion 27. The end 28 is disposed on the inner side in the axial direction of the folded portion 27. The first carcass ply 24 and the second carcass ply 26 constitute a so-called (1 + 1-0) structure.

  The end 28 of the second carcass ply 26 is located radially inward of the end 30 of the first carcass ply 24 that is folded back by the core 20. The end 28 is disposed outside the apex 22 in the axial direction. The second carcass ply 26 and the folded portion 27 are in contact with each other. That is, the end portion 32 of the second carcass ply 26 and the folded portion 27 are bonded. The second carcass ply 26 and the folded portion 27 may not be in contact with each other. The apex 22 may be interposed between the second carcass ply 26 and the folded portion 27.

  Note that the end 28 of the second carcass ply 26 may be positioned on the inner side in the axial direction of the apex 22.

  FIG. 3 is a plan view showing the first carcass ply 24 and the second carcass ply 26 of the tire 2 of FIG. FIG. 3 is an enlarged view near the equator plane CL.

  The first carcass ply 24 includes a large number of first cords 34 and a topping rubber 36 arranged in parallel. In FIG. 3, a straight line L1 is the direction of the first cord 34 on the equator plane CL. The angle θ1 is an angle formed by the first cord 34 with respect to the equator plane CL. The absolute value of the angle θ1 is not less than 85 ° and not more than 90 °. The tire 2 having the first carcass ply 24 is a radial tire.

  In the tire 2, the first cord 34 is usually made of an organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The second carcass ply 26 includes a large number of second cords 38 and a topping rubber 40 arranged in parallel. In FIG. 3, a straight line L2 is the direction of the second cord 38 on the equator plane CL. The angle θ2 is an angle formed by the second cord 38 with respect to the equator plane CL. The angle θ2 is set so that a later-described intersection angle θ3 is 30 ° or more and less than 45 °.

  By increasing the angle θ2, the rigidity of the side portion of the tire can be increased and the steering stability can be improved. In this respect, the angle θ2 is preferably equal to or greater than 40 °, more preferably equal to or greater than 45 °, and still more preferably equal to or greater than 50 °. By reducing the angle θ2, the in-plane torsional rigidity of the tire is increased. By increasing the in-plane torsional rigidity, engine output during acceleration and braking force during deceleration are easily transmitted to the ground. In addition, by improving the in-plane torsional rigidity, the contact pressure distribution is likely to be uniform, and the grip feeling can be improved. From this viewpoint, the angle θ2 is preferably 65 ° or less, and more preferably 60 ° or less.

  The intersection angle θ3 between the second cord 38 and the first cord 34 is 30 ° or more and less than 45 °. As shown in FIG. 3, the intersection angle θ3 is an angle formed by the straight line L1 and the straight line L2. By setting the intersection angle θ3 to be 30 ° or more, the in-plane torsional rigidity of the tire is increased. By increasing the in-plane torsional rigidity, engine output during acceleration and braking force during deceleration are easily transmitted to the ground. In addition, by improving the in-plane torsional rigidity, the contact pressure distribution is likely to be uniform, and the grip feeling can be improved. When the intersection angle θ3 is set to 30 ° or more, steering stability is improved. When the intersection angle θ3 is too large, the rigidity of the side portion of the tire is excessively lowered, and the steering stability tends to deteriorate. From this viewpoint, the crossing angle θ3 is preferably less than 45 °, more preferably 40 ° or less.

  In the present invention, the angle θ1 and the angle θ2 are positive values, negative values, or zero. When the first cord 34 and the second cord 38 are inclined in opposite directions, one of the angle θ1 and the angle θ2 is a positive value and the other is a negative value. The angle θ1 and the angle θ2 are acute angles or right angles. The lower limit of the angle θ1 and the angle θ2 is −90 °, and the upper limit of the angle θ1 and the angle θ2 is 90 °.

  On the other hand, the intersection angle θ3 is a positive value or zero. The lower limit of the intersection angle θ3 is 0 °, and the upper limit of the intersection angle θ3 is 90 °. The intersection angle θ3 formed by the first cord 34 and the second cord 38 is an acute angle or a right angle.

  Note that the angle θ1, the angle θ2, and the crossing angle θ3 are measured on the equator plane.

  In the tire 2, the second cord 38 is usually made of an organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The belt 12 is located on the radially outer side of the carcass 10. The belt 12 is laminated with the carcass 10. The belt 12 reinforces the carcass 10. The belt 12 includes a first belt ply 42 and a second belt ply 44. The belt 12 is composed of two belt plies. The first belt ply 42 is wound in the circumferential direction outside the carcass 10 in the radial direction. The second belt ply 44 is spirally wound substantially in the circumferential direction outside the first belt ply 42 in the radial direction. A belt ply may be further wound in the circumferential direction between the first belt ply and the second belt ply.

  4 is a plan view showing the second carcass ply 26 and the first belt ply 42 of the tire 2 of FIG. FIG. 4 is an enlarged view near the equator plane CL. The first belt ply 42 is laminated outside the second carcass ply 26 in the radial direction. The first belt ply 42 is in contact with the second carcass ply 26.

  The first belt ply 42 includes a large number of third cords 48 and a topping rubber 50 arranged in parallel. In FIG. 4, a straight line L3 is the direction of the third cord 48 on the equator plane CL. The angle θ4 is an angle formed by the third cord 42 with respect to the equator plane CL. The angle θ4 is set in combination with the angle θ1 so that an absolute value θ5 of an intersection angle described later is 25 ° or more and 65 or less. The straight line L3 and the straight line L2 are inclined in the opposite direction with respect to the equator plane. That is, the third cord and the second cord are inclined in opposite directions with respect to the equator plane.

  By setting the angle θ4 to be small, the circumferential rigidity of the tire is increased, and the steering stability is improved. In this respect, the angle θ4 is preferably 60 ° or less, and more preferably 50 ° or less. By setting the angle θ4 to be large, the rigidity in the cross-sectional direction of the tire is increased and the stability during turning is improved. In this respect, the angle θ4 is preferably 30 ° or more, and more preferably 40 ° or more.

  FIG. 5 is a schematic diagram showing the crossing direction of the first cord 34, the second cord 38, and the third cord 48 of the tire 2 of FIG. In the tire 2, the second carcass ply 26 is laminated on the first carcass ply 24. A first belt ply 42 is laminated on the second carcass ply 26. As shown in FIG. 5, in the plan view, the first cord 34, the second cord 38, and the third cord 48 constitute a triangle and are stacked so as to cross each other. The intersection angle θ5 is an intersection angle between the first cord 34 and the third cord 48, and is one of the included angles of the triangle. The intersection angle θ5 is 25 ° or more and 65 ° or less. By setting the intersection angle θ5 to 25 ° or more, the cross-sectional rigidity of the tire is improved. From this viewpoint, the intersection angle θ5 is preferably 30 ° or more. By setting the intersection angle θ5 to 65 ° or less, the circumferential rigidity of the tire is improved. In this respect, the intersection angle θ5 is preferably 55 ° or less.

  In the present invention, the angle θ4 and the crossing angle θ5 are positive values or zero. The lower limit of the angle θ4 and the intersection angle θ5 is 0 °, and the upper limit of the angle θ4 and the intersection angle θ5 is 90 °. The angle θ4 and the intersection angle θ5 are measured on the equator plane.

  Examples of the material of the third cord 48 include nylon fiber, aramid fiber, polyethylene naphthalate fiber, polyester fiber, rayon fiber, glass fiber, carbon fiber, and steel.

  The second belt ply 44 is made of a ribbon (not shown). This ribbon extends substantially in the circumferential direction and is wound spirally. Although not shown, the second belt ply 44 is composed of a fourth cord and a topping rubber. The fourth cord extends substantially in the circumferential direction and is wound spirally. The fourth cord restrains the first belt ply 42 and the carcass 10. The tire 2 is excellent in straight running stability during high speed running. The absolute value of the angle θ6 formed by the fourth cord with respect to the circumferential direction is 5 ° or less, particularly 2 ° or less. The definition of the angle θ6 is the same as the angle θ1 described above. In the present invention, the direction in which the absolute value of the angle θ6 formed with respect to the circumferential direction is 5 ° or less is the “substantially circumferential direction”. The belt 12 has a so-called jointless structure. Examples of the material of the fourth cord include nylon fiber, aramid fiber, polyethylene naphthalate fiber, polyester fiber, rayon fiber, glass fiber, carbon fiber, and steel. The fourth cord having a high elastic modulus and high strength contributes to the straight running stability of the tire 2. From this viewpoint, the material of the fourth cord is preferably aramid fiber and steel. From the viewpoint of straight running stability and turning stability, the material of the fourth cord is particularly preferably steel. Since the fourth cord is a steel cord, the rigidity of the belt is increased. Thereby, straight running stability and turning stability can be improved.

  The second belt ply 44 is spirally wound in a substantially circumferential direction on the first belt ply 42, and the carcass 10 and the first belt ply 42 are restrained more firmly. With this structure, the rigidity of the tire is improved. The improvement in the rigidity of the tire 2 by the first belt ply 42 and the second belt ply 44 can realize high steering stability in combination with an improvement in the appropriate rigidity of the side portion of the tire 2 by the carcass structure. The tire 2 can be compatible at a higher level of handling stability and shock absorption.

  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.

  The chafer 16 is located in the vicinity of the bead 8. When the tire 2 is incorporated into the rim, the chafer 16 comes into contact with the rim. By this contact, the vicinity of the bead 8 is protected. The chafer 16 is usually made of a cloth and a rubber impregnated in the cloth. A chafer 16 made of a single rubber may be used.

  As described above, the end 28 of the second carcass ply 26 is disposed between the main body 25 of the first carcass ply 24 and the folded portion 27. The end 28 is located radially inward from the end 30 of the first carcass ply 24. In FIG. 2, a double arrow H <b> 1 indicates an overlap height between the second carcass ply 26 and the folded portion 27. The height H1 is a length in the radial direction from the end 28 to the end 30. The height H <b> 1 is the height in the radial direction of the overlap portion 52. The overlap portion 52 is generated when the second carcass ply 26 is disposed on the axially outer side or the axially inner side of the folded portion 27. The overlap portion 52 is generated even when the second carcass ply 26 and the folded portion 27 are not in contact with each other.

  From the viewpoint of increasing the rigidity of the side portion of the tire and improving the handling stability, the overlap height H1 is preferably 10 mm or more, and more preferably 15 mm or more. From the viewpoint of increasing impact absorption and suppressing kickback, the overlap height H1 is preferably 30 mm or less, and more preferably 25 mm or less.

  From the viewpoint of further improving the steering stability, it is preferable that the second carcass ply 26 and the folded portion 27 are bonded. The second carcass ply 26 and the folded portion 27 that are in contact with each other are bonded together by vulcanization molding. By this adhesion, the second carcass ply 26 and the folded portion 27 are directly and mutually restrained, so that the stability of the side portion of the tire can be further improved.

  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 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 pneumatic tire for a motorcycle of Example 1 having the basic configuration shown in FIG. 1 and having the specifications shown in Table 1 below was obtained. The tire size is 120 / 70R17. In this tire, the first carcass ply is folded at the bead core. The end of the second carcass ply is located between the apex and the folded portion of the first carcass ply. The tire carcass has a (1 + 1-0) structure. In this tire, the angle θ1 formed by the first cord with respect to the equator plane is 90 °, the angle θ2 formed by the second cord with respect to the equator plane is 60 °, and the intersection of the second cord and the first cord. The angle θ3 is 30 °. The overlap height H1 of this tire is 10 mm. This tire has a first belt ply wound in the circumferential direction and a second belt ply having a jointless structure. The first belt ply has a third cord, and an angle θ5 formed by the third cord with respect to the equator plane is 45 °. The material of the fourth cord of the second belt ply is aramid fiber. As the aramid fiber, Kevlar (registered trademark) manufactured by DuPont was used. The tire bead is a strand bead.

[Comparative Example 1]
A tire was obtained in the same manner as in Example 1 except that the carcass structure was a so-called (1-1) structure, and the angle θ1, the angle θ2, and the crossing angle θ3 were as shown in Table 1. In the carcass having the (1-1) structure, the first carcass ply has a folded portion, and the end of the second carcass ply is located outside the folded portion in the axial direction. The specifications and evaluation results of this tire are shown in Table 1 below.

[Comparative Example 2]
A tire was obtained in the same manner as in Example 1 except that the carcass structure was a so-called (2-0) structure and the angle θ1, the angle θ2, and the crossing angle θ3 were as shown in Table 1. In the carcass having the (2-0) structure, the first carcass ply and the second carcass ply are folded at the bead core. That is, in the carcass having the (2-0) structure, the first carcass ply and the second carcass ply have a folded portion. The specifications and evaluation results of this tire are shown in Table 1 below.

[Comparative Example 6]
A tire of Comparative Example 6 was obtained in the same manner as in Example 1 except that the overlap height H1 was 5 mm. The specifications and evaluation results of this tire are shown in Table 2 below.

[Examples 2 to 4 and Comparative Examples 3 to 5]
Tires of Examples 2 to 4 and Comparative Examples 3 to 5 were obtained in the same manner as in Example 1 except that the angle θ1, the angle θ2, the crossing angle θ3, and the crossing angle θ5 were set as shown in Table 1. .

[Examples 6-9 and Comparative Examples 7-8]
Tires of Examples 6 to 9 and Comparative Examples 7 to 8 were obtained in the same manner as Example 1 except that the angle θ5 was set as shown in Table 2.

[Example 10]
A pneumatic tire for a motorcycle of Example 10 was obtained in the same manner as Example 1 except that the fourth cord was a steel cord. The specifications and evaluation results of this tire are shown in Table 2 below.

[Example 11]
A pneumatic tire for a motorcycle of Example 11 was obtained in the same manner as in Example 1 except that the bead was a cable bead. The specifications and evaluation results of this tire are shown in Table 2 below.

[Measurement of in-plane torsional rigidity]
The in-plane torsional rigidity is measured by rotating the radially innermost circumferential portion (the portion where the chafer is disposed) in the circumferential direction while fixing the radially outermost circumferential portion (tread surface) of the tire. . The in-plane torsional rigidity of Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1 was measured. As a result, in the index value where the in-plane torsional rigidity of Comparative Example 2 is 100, the in-plane torsional rigidity of Comparative Example 1 is 115, the in-plane torsional rigidity of Comparative Example 3 is 95, and the surface of Example 1 The internal torsional rigidity was 160. The tire of Example 1 has high in-plane torsional rigidity.

[Running test]
The tires according to the above examples were mounted on the front wheels of a commercially available motorcycle. As a commercially available motorcycle, GSX-R1000 manufactured by Suzuki was used. The front wheel rim was "17XMT3.50". The air pressure of the front tire was 250 kPa. The rear wheel was fitted with a commercially available conventional tire. The tire size of this rear wheel is 190 / 50R17. The rear wheel rim was set to "17XMT6.00". The air pressure of the rear tire was 290 kPa. Sensory evaluation by riders was conducted on a circuit course composed of dry asphalt roads. Turning performance from 100 km / h to 150 km / h and straight running from the vehicle speed of 250 km / h to the maximum speed of the vehicle (about 280 km / h) were performed, and the straight running stability and turning stability were evaluated. Kickback deterrence was evaluated by running on rough roads. The evaluation values are shown in Tables 1 and 2 below. The straight running stability, turning stability, and kickback deterrence are all index values with the evaluation value of Comparative Example 1 being 100. The higher the index value, the better the straight running stability, turning stability, and kickback deterrence.

  As shown in Tables 1 and 2, the tires of the examples are excellent in straight running stability, turning stability, and kickback deterrence. From this evaluation result, the superiority of the present invention is clear.

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

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 partially enlarged sectional view showing a part of the tire of FIG. FIG. 3 is an enlarged view showing a first carcass ply and a second carcass ply of the tire of FIG. 1. FIG. 4 is an enlarged view showing a second carcass ply and a first belt ply of the tire of FIG. FIG. 5 is a schematic diagram showing the crossing direction of the first code, the second code, and the third code.

Explanation of symbols

2 ... tyre 4 ... tread 6 ... side wall 8 ... bead 10 ... carcass 12 ... belt 14 ... inner liner 16 ... chafer 18 ... tread surface 20 ... Core 22 ... Apex 24 ... First carcass ply 26 ... Second carcass ply 27 ... Turn-up portion 28 ... End of second carcass ply 30 ... First carcass ply End 34 ... first cord 38 ... second cord 42 ... first belt ply 44 ... second belt ply 48 ... third cord θ1 ... first cord on the equator The angle formed with respect to the equator plane. The angle formed between the second code and the first code. The angle formed between the second code and the first code. The angle formed between the third code and the equator plane. ... Third code Crossing angle between the first cord

Claims (4)

A tread whose outer surface forms a tread surface, a pair of beads positioned radially inward of the tread, a carcass spanned between the two beads along the inner side of the tread, and a belt positioned radially inward of the tread And
The carcass includes a first carcass ply that is spanned between both beads, and a second carcass ply that is located radially outward of the first carcass ply,
The first carcass ply includes a first cord, includes a main body and a pair of folded portions continuous from both ends of the main body, and an absolute value of an angle θ1 formed with respect to the equator plane of the first cord is 85. From 90 ° to 90 °,
The second carcass ply includes a second cord, and an end of the second carcass ply is disposed between the folded portion of the first carcass ply and the main body, and has an intersection angle θ3 between the second cord and the first cord. The absolute value is not less than 30 ° and less than 45 ° in the equator plane,
One end in the axial direction of the second carcass ply is disposed between the main body of the first carcass ply and one folded portion in the axial direction, and the other end in the axial direction of the carcass ply is the main body and shaft of the first carcass ply. It is arranged between the other folded portion in the direction,
The overlap height H1 between the second carcass ply and the folded portion is 10 mm or more,
The belt includes a first belt ply positioned circumferentially outside the carcass in the circumferential direction, and a second belt ply spirally wound substantially circumferentially outside the first belt ply,
The first belt ply has a third cord,
The third cord is inclined in the opposite direction to the second cord with respect to the equator plane, and the absolute value of the intersection angle θ5 between the third cord and the first cord is 25 ° to 65 ° at the equator plane,
A pneumatic tire for a motorcycle in which the second belt ply has a fourth cord.   The pneumatic tire for a motorcycle according to claim 1, wherein the second carcass ply and the folded portion are bonded to each other.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the fourth cord is a steel cord.   The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein the bead includes a core and an apex extending radially outward from the core, and the beat is a cable bead.

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