JP2018069782A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire 2 attaining improvement in steering stability without impairing abrasion resistance.SOLUTION: A tire 2 comprises a reinforcement part 18 positioned at a region which transits from a tread 4 to a side wall 6. The reinforcement part 18 comprises an inner reinforcement layer 40 and an outer reinforcement layer 42. The inner reinforcement layer 40 is positioned between an inner liner 16 and a carcass ply. The outer reinforcement layer 42 is positioned between the carcass ply and the side wall 6. The inner reinforcement layer 40 includes a first reinforcement cord 52a. The first reinforcement cord 52a inclines with respect to the carcass cord 54. The outer reinforcement layer 42 includes a second reinforcement cord 52b. The second reinforcement cord 52b inclines with respect to the carcass cord 54.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire. More specifically, the present invention relates to a pneumatic tire provided with a carcass having a radial structure.

  The tire has a carcass. The carcass is stretched between the beads on both sides along the inside of the tread and the sidewall.

  The carcass includes a carcass ply. The carcass ply includes a large number of cords arranged in parallel. In the carcass having a radial structure, the absolute value of the angle formed by each cord with respect to the equator plane is set in the range of 75 ° to 90 °. A tire having a carcass having a radial structure is also referred to as a radial tire.

  Steering stability is one of the important performances of tires. Various studies have been conducted on improving steering stability. An example of this study is disclosed in Japanese Unexamined Patent Application Publication No. 2009-202647. In the tire described in this publication, a reinforcing layer is provided in a region where the tire transitions from the tread to the sidewall, that is, the buttress of the tire. The reinforcing layer is disposed along the outside of the radial structure carcass. The reinforcing layer includes a cord that extends at an angle to the carcass cord. The main function of this reinforcing layer is to improve the rigidity of the tire.

  As the cord of the reinforcing layer, a cord made of organic fiber (hereinafter referred to as organic fiber cord) is generally used. In the tire described in the above publication, a cord made of aramid fiber is used as a cord for the reinforcing layer.

JP 2009-202647 A

  If the reinforcing layer containing the organic fiber cord is in an environment where force is applied in the direction in which the cord is pulled, it effectively contributes to the rigidity of the tire and can fully exhibit its function. However, if this reinforcing layer is present in an environment where a force acts in the direction in which the cord is compressed, this reinforcing layer cannot sufficiently perform its function as much as it contributes to the shear rigidity with the carcass.

  In the conventional tire, as described above, the reinforcing layer is located outside the carcass in the buttress. Considering the case where the vehicle turns to the right, for example, in a tire located on the left side (hereinafter referred to as a left side tire) with respect to the traveling direction of the vehicle, a buttress (hereinafter referred to as an outer side in the width direction of the vehicle). The load is placed on the outside buttress. For this reason, a force acts in the direction in which the cord is compressed on the reinforcing layer located on the outside buttress of the left side tire. On the other hand, a force acts in a direction in which the cord is pulled on the reinforcing layer in the buttress (hereinafter referred to as the inside buttress) located on the inner side in the turning direction, that is, on the inner side in the width direction of the vehicle. In the tire located on the right side with respect to the traveling direction of the vehicle (hereinafter, the light side tire), a load is placed on the inside buttress on the outside of the turn, that is, the inside of the vehicle in the width direction. A force is applied to the reinforcing layer positioned in the inside buttress in the direction in which the cord is compressed. On the other hand, a force acts in the direction in which the cord is pulled on the reinforcing layer on the inside buttress on the inside of the turn, that is, on the outside in the width direction of the vehicle.

  In the swiveling state, one reinforcing layer is in an environment in which a force acts in the direction in which the cord is pulled, and the other reinforcing layer is in an environment in which a force acts in the direction in which the cord is compressed. As described above, if there is a reinforcing layer in an environment where a force acts in the direction in which the cord is compressed, this reinforcing layer contributes to the shear rigidity with the carcass and cannot fully exhibit its function. That is, in this tire, although one reinforcing layer is provided on each of the left and right buttresses, only one of the reinforcing layers can sufficiently perform its function. Moreover, it is not the reinforcing layer in the buttress on which a load is placed during turning, that is able to perform its function. In addition, since a difference in rigidity occurs between the left and right buttresses, a difference occurs in the lateral force acting on the tread surface, and the tread surface is slidable with respect to the road surface, and the tread is likely to be unevenly worn.

  With regard to the technology that improves the rigidity of the tire and improves the steering stability by providing a reinforcing layer including cords on the buttress, it cannot be said that the function of the reinforcing layer has been fully demonstrated, and there is room for improvement. is there.

  An object of the present invention is to provide a pneumatic tire in which improvement in steering stability is achieved without impairing wear resistance.

  The pneumatic tire according to the present invention includes a tread, a pair of sidewalls, a pair of beads, a carcass, a belt, an inner liner, and a pair of reinforcing portions. Each sidewall extends substantially inward in the radial direction from the end of the tread. Each bead is located radially inward of the sidewall. The carcass has a radial structure, and is bridged between one bead and the other bead along the inside of the tread and the sidewall. The belt is laminated with the carcass on the inner side in the radial direction of the tread. The inner liner is located inside the carcass. Each reinforcement part is located in the area | region which changes to the said sidewall from the said tread. The carcass includes a carcass ply. The carcass ply includes a carcass cord. The reinforcing part includes an inner reinforcing layer and an outer reinforcing layer. The inner reinforcing layer is located between the inner liner and the carcass ply. The outer reinforcing layer is located between the carcass ply and the sidewall. The inner reinforcing layer includes a first reinforcing cord. The first reinforcing cord is inclined with respect to the carcass cord. The outer reinforcing layer includes a second reinforcing cord. The second reinforcing cord is inclined with respect to the carcass cord.

  Preferably, in this pneumatic tire, the outer end of the outer reinforcing layer is positioned radially outward from the outer end of the inner reinforcing layer, and the inner end of the outer reinforcing layer is the inner end of the inner reinforcing layer. It is located inward in the radial direction.

  Preferably, in the pneumatic tire, the outer end of the outer reinforcing layer is located between the carcass and the belt, and the inner end of the outer reinforcing layer is inside the outer end of the bead in the radial direction. Is located.

  Preferably, in the pneumatic tire, the outer end of the inner reinforcing layer is located inward of the end of the belt in the radial direction, and the inner end of the inner reinforcing layer is more radially than the outer end of the bead. Is also located on the outside.

  Preferably, in the pneumatic tire, the carcass ply includes a main portion and a pair of folded portions. The main part bridges between one bead and the other bead. Each folded portion extends substantially outward in the radial direction from the bead.

  Preferably, in this pneumatic tire, the inclination direction of the first reinforcing cord with respect to the carcass cord is opposite to the inclination direction of the second supply cord with respect to the carcass cord.

  Preferably, in this pneumatic tire, the absolute value of the first inclination angle α formed by the first reinforcing cord with respect to the carcass cord is 20 ° or more and 45 ° or less. The absolute value of the second inclination angle β formed by the second reinforcing cord with respect to the carcass cord is 20 ° or more and 45 ° or less.

  Preferably, in this pneumatic tire, the absolute value of the first inclination angle α is equal to the absolute value of the second inclination angle β.

  In the pneumatic tire according to the present invention, the reinforcing portion disposed on the buttress includes an inner reinforcing layer and an outer reinforcing layer. The inner reinforcing layer is located inside the carcass, and the outer reinforcing layer is located outside the carcass. The inner reinforcing layer includes a first reinforcing cord extending at an inclination with respect to the carcass cord, and the outer reinforcing layer includes a second reinforcing cord extending at an inclination with respect to the carcass cord.

  In this tire, the inner reinforcing layer contributes to the rigidity of the tire in one buttress located outside the turning in the turning state, and the outer reinforcing layer contributes to the rigidity of the tire in the other buttress located inside the turning. In other words, in this tire, the reinforcing portions provided on the left and right buttresses effectively contribute to improving the tire rigidity. In this tire, even in a buttress on which a load is placed during turning, the reinforcing portion can sufficiently exhibit its function. In this tire, improvement in handling stability is achieved.

  In this tire, improvement in rigidity is achieved in each of the left and right buttresses. In this tire, the difference in stiffness between the left and right buttresses is small in the turning state. Since the sliding of the tread surface with respect to the road surface is suppressed, uneven wear is unlikely to occur in this tire. In this tire, good wear resistance is maintained.

  As is apparent from the above description, in this tire, improvement in steering stability is achieved without impairing wear resistance. In other words, according to the present invention, it is possible to obtain a pneumatic tire in which improvement in handling stability is achieved without impairing wear resistance.

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 schematic diagram showing the arrangement of cords in the reinforcing portion of the tire of FIG. FIG. 3 is a cross-sectional view showing a part of a pneumatic tire according to another embodiment of the present invention.

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

  FIG. 1 shows a pneumatic tire 2. In FIG. 1, the vertical direction is the radial direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. In FIG. 1, an alternate long and short dash line CL represents the equator plane of the tire 2. The shape of the tire 2 is symmetrical with respect to the equator plane except for the tread pattern.

  The tire 2 includes a tread 4, a pair of sidewalls 6, a pair of beads 8, a carcass 10, a belt 12, a band 14, an inner liner 16, and a pair of reinforcing portions 18. The tire 2 is a tubeless type. The tire 2 is attached to a vehicle (four-wheeled vehicle) traveling on a circuit. The tire 2 is for racing.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 20 that touches the road surface. The tread 4 is made of a crosslinked rubber. In the tread 4, wear resistance, heat resistance, and grip properties are taken into consideration. The tread 4 has no groove. The tire 2 is a slick type. Grooves may be cut into the tread 4 to form a tread pattern.

  Each sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. This sidewall 6 is made of a crosslinked rubber having excellent cut resistance and weather resistance. The sidewall 6 is located outside the carcass 10 in the axial direction. The sidewall 6 prevents the carcass 10 from being damaged.

  Each bead 8 is located radially inward of the sidewall 6. The bead 8 includes a core 22 and an apex 24. The core 22 is ring-shaped and includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 24 extends radially outward from 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 first carcass ply 26 (hereinafter referred to as a first ply) and a second carcass ply 28 (hereinafter referred to as a second ply). The carcass 10 is composed of two carcass plies. The carcass 10 may be formed from one carcass ply, or may be formed from three or more carcass plies.

  In the tire 2, the first ply 26 and the second ply 28 are spanned between the beads 8 on both sides, and are along the inside of the tread 4 and the sidewall 6.

  The first ply 26 is folded around each core 22 from the inner side to the outer side in the axial direction. Due to this folding, the first ply 26 is formed with a first main portion 26a and a pair of first folding portions 26b. In other words, the first ply 26 includes a first main portion 26a and a pair of first folded portions 26b. The first main portion 26 a bridges between the core 22 of one bead 8 and the core 22 of the other bead 8. Each first folded portion 26b extends from the core 22 substantially outward in the radial direction.

  The second ply 28 is folded back from the inner side to the outer side in the axial direction around each core 22. By this folding, the second ply 28 is formed with a second main portion 28a and a pair of second folding portions 28b. In other words, the second ply 28 includes a second main portion 28a and a pair of second folded portions 28b. The second main portion 28 a bridges between the core 22 of one bead 8 and the core 22 of the other bead 8. Each second folded portion 28b extends from the core 22 substantially outward in the radial direction. On the inner side of the tread 4, the second main portion 28a is located on the radially outer side of the first main portion 26a. Inside the sidewall 6, the second main portion 28a is located on the outer side in the axial direction of the first main portion 26a. The first folded portion 26b is located on the outer side in the axial direction of the second folded portion 28b.

  In the tire 2, the end 30 of the first folded portion 26b is located on the inner side of the end 32 of the second folded portion 28b in the radial direction. The end 30 of the first folded portion 26b may be positioned outside the end 32 of the second folded portion 28b in the radial direction. When the end 30 of the first folded portion 26b is positioned outside the end 32 of the second folded portion 28b in the radial direction, the first folded portion 26b is a second folded portion, which will be described later. The same effect as 28b is produced.

  Each of the first ply 26 and the second ply 28 includes a large number of carcass cords and topping rubbers arranged in parallel. The carcass ply includes a large number of carcass cords arranged in parallel. Although not shown, these carcass cords are covered with a topping rubber. In other words, these carcass cords are embedded in the topping rubber. The absolute value of the angle formed by each carcass cord with respect to the equator plane is 75 ° to 90 °. In other words, the carcass 10 has a radial structure. 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 belt 12 is located on the inner side in the radial direction of the tread 4. The belt 12 is laminated with the carcass 10. The belt 12 reinforces the carcass 10. The belt 12 includes an inner layer 34 and an outer layer 36. As apparent from FIG. 1, the width of the inner layer 34 is slightly larger than the width of the outer layer 36 in the axial direction.

  Although not shown, each of the inner layer 34 and the outer layer 36 is composed of a large number of cords arranged in parallel and a topping rubber. In each of the inner layer 34 and the outer layer 36, these cords are covered with a topping rubber. Each cord is inclined with respect to the equator plane. The general absolute value of the tilt angle is 10 ° or more and 35 ° or less. The inclination direction of the cord of the inner layer 34 with respect to the equator plane is opposite to the inclination direction of the cord of the outer layer 36 with respect to the equator plane. A preferred material for the cord is steel. An organic fiber may be used for the cord. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. The axial width of the belt 12 is preferably 0.7 times or more the maximum width of the tire 2 (also referred to as a cross-sectional width (referred to JATMA)).

  The band 14 is located outside the belt 12 in the radial direction. In the tire 2, the width of the band 14 is equal to the width of the belt 12 in the axial direction. The band 14 may be configured such that the width of the band 14 is larger than the width of the belt 12.

  Although not shown, the band 14 is composed of a cord and a topping rubber. This cord is covered with a topping rubber. The cord is wound in a spiral. The band 14 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is 5 ° or less, and further 2 ° or less. Since the belt 12 is restrained by this cord, lifting of the belt 12 is suppressed. The cord is made of organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The inner liner 16 is located inside the carcass 10. In the tire 2, the inner liner 16 is joined to the inner surface of the carcass 10. The inner liner 16 is made of a crosslinked rubber having excellent air shielding properties. A typical base rubber of the inner liner 16 is butyl rubber or halogenated butyl rubber. The inner liner 16 holds the internal pressure of the tire 2.

  Each reinforcement part 18 is located in the area | region which changes from the tread 4 to the sidewall 6, or the area | region which changes from the sidewall 6 to the tread 4. In the tire 2, a region where the tread 4 transitions to the sidewall 6 or a region where the sidewall 6 transitions to the tread 4 is also referred to as a buttress 38. That is, the reinforcing portion 18 is located on the buttress 38 of the tire 2.

  In the tire 2, the reinforcing portion 18 includes an inner reinforcing layer 40 and an outer reinforcing layer 42. The inner reinforcing layer 40 constitutes an inner portion of the reinforcing portion 18, and the outer reinforcing layer 42 constitutes an outer portion of the reinforcing portion 18.

  The inner reinforcing layer 40 is located inside the carcass 10. Specifically, the inner reinforcing layer 40 is located between the inner liner 16 and the first main portion 26 a of the first ply 26. As shown in FIG. 1, the outer end 44 of the inner reinforcing layer 40 is located inside the end 12 a of the belt 12 in the radial direction. The inner end 46 of the inner reinforcing layer 40 is located outside the outer end 8 a of the bead 8, specifically, the outer end 8 a of the apex 24 in the radial direction.

  In the tire 2, a part of the second folded portion 28 b is positioned outside the outer reinforcing layer 42, but the outer reinforcing layer 42 is generally positioned outside the carcass 10. Specifically, the outer reinforcing layer 42 is located between the second main portion 28 a of the second ply 28 and the sidewall 6. As shown in FIG. 1, the outer end 48 of the outer reinforcing layer 42 is located inside the end 12 a of the belt 12 in the axial direction. The inner end 50 of the outer reinforcing layer 42 is located inside the outer end 8a of the apex 24 in the radial direction.

  In the tire 2, each of the inner reinforcing layer 40 and the outer reinforcing layer 42 includes a large number of reinforcing cords arranged in parallel. FIG. 2 schematically shows the arrangement of the reinforcing cords 52 together with the arrangement of the carcass cords 54 included in each of the first ply 26 and the second ply 28 constituting the carcass 10. In FIG. 2, the back side of the paper surface corresponds to the inside of the tire 2, and the front side of the paper surface corresponds to the outside of the tire 2. In FIG. 2, the vertical direction corresponds to the radial direction of the tire 2, and the horizontal direction corresponds to the circumferential direction of the tire 2.

  The inner reinforcing layer 40 includes a large number of first reinforcing cords 52a arranged in parallel. Specifically, the inner reinforcing layer 40 includes a plurality of first reinforcing cords 52a and a topping rubber 56a. In this drawing, for convenience of explanation, the first reinforcing cord 52a is represented by a thick solid line, but in the inner reinforcing layer 40, the first reinforcing cord 52a is covered with a topping rubber 56a.

  In the tire 2, each first reinforcing cord 52a is inclined with respect to the radial direction. Since the carcass 10 has a radial structure, the carcass cord 54 included in the carcass 10 extends substantially in the radial direction. In the tire 2, the first reinforcing cord 52 a is inclined with respect to the carcass cord 54.

  In the tire 2, the first reinforcing cord 52a is made of an organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The outer reinforcing layer 42 includes a large number of second reinforcing cords 52b arranged in parallel. Specifically, the outer reinforcing layer 42 includes a plurality of second reinforcing cords 52b and a topping rubber 56b. In this drawing, for convenience of explanation, the second reinforcing cord 52b is represented by a thick solid line, but in the outer reinforcing layer 42, the second reinforcing cord 52b is covered with a topping rubber 56b.

  In the tire 2, each second reinforcing cord 52b is inclined with respect to the radial direction. As described above, the carcass cord 54 extends substantially in the radial direction. In the tire 2, the second reinforcing cord 52 b is inclined with respect to the carcass cord 54.

  In the tire 2, the second reinforcing cord 52b is made of an organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  Various forces act on the tire 2 when the vehicle (four-wheeled vehicle) is turning. Hereinafter, the force acting on the buttress 38 of the tire 2 will be described in detail.

  For example, when the vehicle turns to the right, in the tire 2 (hereinafter referred to as the left side tire) located on the left side with respect to the traveling direction of the vehicle, the buttress 38 (hereinafter referred to as the following in the width direction of the vehicle). A load is placed on the outside buttress. At this time, a force acts on the outer portion of the outside buttress 38 in the direction of compressing the outer portion. On the other hand, a force acts on the inner portion of the outside buttress 38 in the direction of extending the inner portion. In the buttress 38 (hereinafter referred to as the inside buttress) located inside the turning, that is, on the inner side in the width direction of the vehicle, a force acts on the outer portion in the direction of extending the outer portion, and the inner portion is compressed on the inner portion. Force acts in the direction of In the tire 2 (hereinafter referred to as a light side tire) located on the right side with respect to the traveling direction of the vehicle, a load is placed on the inside buttress 38 on the outer side of the turn. A force acts in the direction of compressing the inner portion, and a force acts on the inner portion in the direction of extending the inner portion. In the right side tire 2, a force acts on the outer portion of the outside buttress 38 inside the turn in the direction of extending the outer portion, and a force acts on the inner portion in a direction of compressing the inner portion.

  As described above, in the buttress 38 of the tire 2, the inner reinforcing layer 40 is located inside the carcass 10, and the outer reinforcing layer 42 is located outside the carcass 10. That is, in the above-described left side tire 2, the inner reinforcing layer 40 is located on the inner portion of the outside buttress 38 located on the outer side of the turn where the force acts in the extending direction, and the force acts in the same extending direction. An outer reinforcing layer 42 is positioned on the outer portion of the inside buttress 38 positioned on the inside of the turn. Also in the light side tire 2 described above, the inner reinforcing layer 40 is located on the inner part of the inside buttress 38 located on the outer side of the turn where the force acts in the extending direction, and the force acts on the inner side of the turning. An outer reinforcing layer 42 is positioned on the outer portion of the outer buttress 38 that is positioned.

  In the tire 2, the inner reinforcement layer 40 includes a first reinforcement cord 52 a that extends with an inclination with respect to the carcass cord 54, and the second reinforcement in which the outer reinforcement layer 42 extends with an inclination with respect to the carcass cord 54. The code 52b is included. Therefore, in the tire 2, the inner reinforcing layer 40 contributes to the rigidity of the tire 2 in the one buttress 38 positioned on the outer side in the turning state, and the outer reinforcing layer 42 in the other buttress 38 positioned on the inner side of the turning. Contributes to the rigidity of the tire 2. In other words, in the tire 2, the reinforcing portions 18 provided on the left and right buttresses 38 effectively contribute to improving the rigidity of the tire 2. In the tire 2, the reinforcing portion 18 can sufficiently exert its function even in the buttress 38 on which a load is placed during turning. In the tire 2, an improvement in steering stability is achieved.

  In the tire 2, improvement in rigidity is achieved in each of the left and right buttresses 38. In the tire 2, the difference in rigidity between the left and right buttresses 38 is small in the turning state. Since slippage of the tread surface 20 with respect to the road surface is suppressed, uneven wear is unlikely to occur in the tire 2. In the tire 2, good wear resistance is maintained.

  As is clear from the above description, in the tire 2, improvement in steering stability is achieved without impairing wear resistance. In other words, according to the present invention, it is possible to obtain the pneumatic tire 2 in which the improvement in handling stability is achieved without impairing the wear resistance.

  As shown in FIG. 1, in the tire 2, the outer end 48 of the outer reinforcing layer 42 is located radially outward from the outer end 44 of the inner reinforcing layer 40. The end 50 is located radially inward from the inner end 46 of the inner reinforcing layer 40. In other words, in the tire 2, the inner reinforcing layer 40 is short and the outer reinforcing layer 42 is long. In the tire 2 in the turning state, a large load is placed on the buttress 38 positioned on the outer side of the turning, but a very large load is not placed on the buttress 38 on the inner side of the turning. For this reason, the right and left buttresses 38 are configured by configuring the reinforcing portion 18 so that the inner reinforcing layer 40 that contributes to the rigidity of the buttress 38 outside the turning is short and the outer reinforcing layer 42 that contributes to the rigidity of the inside paddle is long. The rigidity balance is properly adjusted. In the tire 2, the difference in rigidity between the left and right buttresses 38 is small. Since the sliding of the tread surface 20 with respect to the road surface is effectively suppressed, uneven wear is unlikely to occur in the tire 2. The tire 2 is excellent in wear resistance. From this point of view, in the tire 2, the outer end 48 of the outer reinforcing layer 42 is positioned radially outward from the outer end 44 of the inner reinforcing layer 40, and the inner end 50 of the outer reinforcing layer 42 is the inner reinforcing layer 40. It is preferable that it is located inward in the radial direction from the inner end 46.

  In the tire 2, the outer end 48 of the outer reinforcing layer 42 is located between the carcass 10 and the belt 12. The inner end 50 of the outer reinforcing layer 42 is located inside the outer end 8a of the bead 8 in the radial direction. In the tire 2, the outer reinforcing layer 42 overlaps with the belt 12 and the bead 8. The outer reinforcing layer 42 effectively suppresses deformation of the buttress 38 in the traveling state. In the tire 2, since the lifting of the end 12a of the belt 12 is suppressed, the durability can be further improved. From this point of view, the outer end 48 of the outer reinforcing layer 42 is located between the carcass 10 and the belt 12, and the inner end 50 of the outer reinforcing layer 42 is inward of the outer end 8 a of the bead 8 in the radial direction. It is preferably located.

  In FIG. 1, a solid line LB is a normal line of the outer surface of the outer reinforcing layer 42. This normal LB passes through the end 12a of the belt 12. A double arrow SB represents a distance from the outer end 48 of the outer reinforcing layer 42 to the normal line LB. The distance SB is measured along the outer reinforcing layer 42 in the cross section of the tire 2 shown in FIG. In the present invention, this distance SB is the overlapping length of the outer reinforcing layer 42 and the belt 12. A solid line LA is also a normal line of the outer surface of the outer reinforcing layer 42. This normal LA passes through the outer end 8 a of the bead 8. A double-headed arrow SA represents the distance from the inner end 50 of the outer reinforcing layer 42 to the normal line LA. This distance SA is measured along the outer reinforcing layer 42 in the cross section shown in FIG. In the present invention, this distance SA is the overlapping length of the outer reinforcing layer 42 and the bead 8.

  In the present invention, the lengths SB and SA can take various values, but when the length SB is expressed by a positive number, it indicates that the outer reinforcing layer 42 and the belt 12 overlap. When the length SB is expressed as a negative number, the outer reinforcing layer 42 and the belt 12 are separated from each other. When the length SA is represented by a positive number, it indicates that the outer reinforcing layer 42 and the bead 8 are overlapped, and when the length SA is represented by a negative number, the outer reinforcement is provided. It represents that the layer 42 and the bead 8 are separated.

  In the tire 2, the overlapping length SB between the outer reinforcing layer 42 and the belt 12 is preferably 3 mm or more, and preferably 10 mm or less. By setting the length SB to be 3 mm or more, the outer reinforcing layer 42 effectively suppresses deformation of the buttress 38. The outer reinforcing layer 42 contributes to the durability of the tire 2. Moreover, since the contact pressure of the shoulder portion of the tire 2 is properly maintained, uneven wear hardly occurs. The tire 2 is also excellent in wear resistance. In this respect, the length SB is more preferably 4 mm or more. By setting the length SB to 10 mm or less, the rigidity of the overlapping portion between the outer reinforcing layer 42 and the belt 12 is appropriately maintained. In the tire 2, the rigidity of the overlapping portion is not unique. In the tire 2, the portion from the tread 4 to the bead 8 flexes flexibly. In the tire 2, good steering stability is appropriately maintained. In this respect, the length SB is more preferably 9 mm or less.

  In the tire 2, the overlap length SA between the outer reinforcing layer 42 and the bead 8 is preferably 3 mm or more, and preferably 10 mm or less. By setting the length SA to 3 mm or more, the outer reinforcing layer 42 effectively suppresses deformation of the buttress 38. The outer reinforcing layer 42 contributes to the durability of the tire 2. Moreover, since the contact pressure of the shoulder portion of the tire 2 is properly maintained, uneven wear hardly occurs. The tire 2 is also excellent in wear resistance. In this respect, the length SA is more preferably 4 mm or more. By setting the length SA to 10 mm or less, the rigidity of the overlapping portion between the outer reinforcing layer 42 and the bead 8 is appropriately maintained. In the tire 2, the rigidity of the overlapping portion is not unique. In the tire 2, the portion from the tread 4 to the bead 8 flexes flexibly. In the tire 2, good steering stability is appropriately maintained. In this respect, the length SA is more preferably 9 mm or less.

  As described above, in the tire 2, the outer end 44 of the inner reinforcing layer 40 is located inward of the end 12 a of the belt 12 in the radial direction, and the inner end 46 of the inner reinforcing layer 40 is beaded in the radial direction. 8 is located outside the outer end 8a. In the tire 2, the inner reinforcing layer 40 does not overlap with the belt 12. The inner reinforcing layer 40 does not overlap with the bead 8. Thereby, in the tire 2, the rigidity of the end 12a portion of the belt 12 and the outer end 8a portion of the bead 8 is appropriately maintained. In the tire 2, the rigidity of the end 12a portion of the belt 12 and the outer end 8a portion of the bead 8 is not unique. In the tire 2, the portion from the tread 4 to the bead 8 flexes flexibly. In the tire 2, good steering stability is appropriately maintained. Moreover, since the contact pressure of the shoulder portion of the tire 2 is properly maintained, uneven wear hardly occurs. The tire 2 is also excellent in wear resistance. From this point of view, the outer end 44 of the inner reinforcing layer 40 is located inward of the end 12a of the belt 12 in the radial direction, and the inner end 46 of the inner reinforcing layer 40 is outer than the outer end 8a of the bead 8 in the radial direction. It is preferable that it is located in.

  In FIG. 1, the double-headed arrow UB represents the distance from the outer end 44 of the inner reinforcing layer 40 to the normal line LB. The distance UB is measured along the carcass 10 in the cross section of the tire 2 shown in FIG. In the present invention, this distance UB is the distance between the belt 12 and the inner reinforcing layer 40. A double-headed arrow UA represents the distance from the inner end 46 of the inner reinforcing layer 40 to the normal line LA. This distance UA is measured along the carcass 10 in the cross section shown in FIG. In the present invention, this distance UA is the distance between the inner reinforcing layer 40 and the bead 8.

  In the present invention, the distances UB and UA can take various values. When the distance UB is expressed by a negative number, the inner reinforcing layer 40 and the belt 12 are separated from each other. When the distance UB is represented by a positive number, it indicates that the inner reinforcing layer 40 and the belt 12 are overlapped. When the distance UA is represented by a negative number, the inner reinforcing layer 40 and the bead 8 are separated from each other. When the distance UA is represented by a positive number, the inner reinforcing layer 40 is separated. And bead 8 are overlapped.

  In the tire 2, the separation distance UB between the belt 12 and the inner reinforcing layer 40 is preferably -3 mm or less. By setting the distance UB to be −3 mm or less, the rigidity between the belt 12 and the inner reinforcing layer 40 is appropriately maintained. In the tire 2, the portion from the tread 4 to the bead 8 flexes flexibly. In the tire 2, good steering stability is appropriately maintained. Moreover, since the contact pressure of the shoulder portion of the tire 2 is properly maintained, uneven wear hardly occurs. The tire 2 is also excellent in wear resistance. Since the concentration of strain on the end 12a of the belt 12 or the outer end 44 of the inner reinforcing layer 40 is suppressed, good durability is also maintained. When the distance UB is reduced, that is, when the inner reinforcing layer 40 is disposed away from the end 12a of the belt 12, the inner reinforcing layer 40 is insufficient in length, and the balance between steering stability and wear resistance may be lost. There is. From the viewpoint of sufficiently securing the length of the inner reinforcing layer 40, the distance UB is preferably -10 mm or more, more preferably -7 mm or more, and further preferably -5 mm or more.

  In the tire 2, the separation distance UA between the inner reinforcing layer 40 and the bead 8 is preferably -3 mm or less. By setting the distance UA to be −3 mm or less, the rigidity between the bead 8 and the inner reinforcing layer 40 is appropriately maintained. In the tire 2, the portion from the tread 4 to the bead 8 flexes flexibly. In the tire 2, good steering stability is appropriately maintained. Moreover, since the contact pressure of the shoulder portion of the tire 2 is properly maintained, uneven wear hardly occurs. The tire 2 is also excellent in wear resistance. Since the concentration of strain on the outer end 8a of the bead 8 or the inner end 46 of the inner reinforcing layer 40 is suppressed, good durability is also maintained. When the distance UA is reduced, that is, when the inner reinforcing layer 40 is disposed away from the outer end 8a of the bead 8, the inner reinforcing layer 40 is insufficient in length, and the balance between steering stability and wear resistance is lost. There is a fear. From the viewpoint of sufficiently securing the length of the inner reinforcing layer 40, the distance UA is preferably −10 mm or more, more preferably −7 mm or more, and further preferably −5 mm or more.

  As shown in FIG. 1, in the tire 2, the end 32 portion of the second folded portion 28 b is sandwiched between the outer reinforcing layer 42 and the side wheels. In other words, the end 32 portion of the second folded portion 28 b is located on the outer side in the axial direction of the outer reinforcing layer 42. Specifically, the second folded portion 28 b is laminated on the outer side of the outer reinforcing layer 42. In the tire 2, the shear rigidity generated between the outer reinforcing layer 42 and the second folded portion 28b is larger than that of the tire in which the second folded portion 28b is disposed inside the outer reinforcing layer 42. The large shear rigidity contributes to the steering stability of the tire 2. From this viewpoint, it is preferable that the second folded portion 28b is laminated on the outer side of the outer reinforcing layer 42.

  Adjustment of the overlapping length of the second folded portion 28b and the outer reinforcing layer 42 (the length indicated by the double arrow LT in FIG. 1) is effective for adjusting the rigidity of the tire 2. For this reason, in the tire 2, the position of the end 32 of the second folded portion 28b is appropriately adjusted between the outer end 48 of the outer reinforcing layer 42 and the inner end 50 thereof. In a portion from the tread 4 to the bead 8 of the tire 2, an end 12 a of the belt 12, an outer end 8 a of the bead 8, an outer end 44 and an inner end 46 of the inner reinforcing layer 40, an outer end 48 of the outer reinforcing layer 42, and The inner end 50 is located. Therefore, for example, when the second folded portion 28b is arranged so that the end 32 of the second folded portion 28b overlaps any of these ends, distortion is concentrated on the end 32 of the second folded portion 28b. In addition, the durability of the tire 2 may be impaired. From the standpoint that the rigidity of the tire 2 can be effectively adjusted without impairing the durability, the end 32 of the second folded portion 28b includes the end 12a of the belt 12, the outer end 8a of the bead 8, and the inner reinforcing layer 40. The outer end 44, the inner end 46 of the inner reinforcing layer 40, the outer end 48 of the outer reinforcing layer 42, and the inner end 50 of the outer reinforcing layer 42 are preferably arranged apart from each other. From the viewpoint of suppressing the concentration of strain, the end 32 of the second folded portion 28b includes the end 12a of the belt 12, the outer end 8a of the bead 8, the outer end 44 of the inner reinforcing layer 40, and the inner end of the inner reinforcing layer 40. It is more preferable that the end 46, the outer end 48 of the outer reinforcing layer 42, and the inner end 50 of the outer reinforcing layer 42 are spaced apart by 3 mm or more.

  As shown in FIG. 2, the inclination direction of the first reinforcement cord 52a with respect to the carcass cord 54 is opposite to the inclination direction of the second reinforcement cord 52b with respect to the carcass cord 54. In the tire 2, the reinforcing portion 18 and the carcass are compared with the tire 2 configured such that the inclination direction of the first reinforcement cord 52a with respect to the carcass cord 54 is the same as the inclination direction of the second reinforcement cord 52b with respect to the carcass cord 54. The shear rigidity that occurs between 10 and 10 is large. The large shear rigidity contributes to the steering stability of the tire 2. From this viewpoint, in the tire 2, it is preferable that the inclination direction of the first reinforcement cord 52a with respect to the carcass cord 54 is opposite to the inclination direction of the second reinforcement cord 52b with respect to the carcass cord 54.

  In FIG. 2, the angle α represents a first inclination angle formed by the first reinforcing cord 52 a with respect to the carcass cord 54. The carcass cord 54 serving as a reference for the first inclination angle α is the carcass cord 54 included in the carcass ply adjacent to the inner reinforcing layer 40. In the tire 2 shown in FIG. 1, it is the first ply 26 that is adjacent to the inner reinforcing layer 40, more specifically, the first main portion 26a of the first ply 26. Based on the included carcass cord 54, this first inclination angle α is obtained.

  In the tire 2, the absolute value of the first inclination angle α is preferably 20 ° or more, and preferably 45 ° or less from the viewpoint that the inner reinforcing layer 40 effectively contributes to the rigidity of the buttress 38 in the extended environment. In particular, when the absolute value of the first inclination angle α is set to 20 ° or more, the inner reinforcing layer 40 exerts a large tension in an extended environment. By setting the absolute value of the first inclination angle α to 45 ° or less, the inner reinforcing layer 40 contributes to a large shear rigidity in an extended environment. When the contribution due to the shear stiffness is dominant, better steering stability can be achieved while improving the durability. Therefore, in the tire 2, the absolute value of the first inclination angle α is 35 ° or more. More preferred. More preferably 40 ° or more. Particularly preferably, the absolute value of the first inclination angle α is set to 45 °.

  In FIG. 2, the angle β represents the second inclination angle formed by the second reinforcing cord 52 b with respect to the carcass cord 54. The carcass cord 54 serving as a reference for the second inclination angle β is the carcass cord 54 included in the carcass ply adjacent to the outer reinforcing layer 42. In the tire 2 shown in FIG. 1, it is the second ply 28 that is adjacent to the outer reinforcing layer 42, more specifically, the second main portion 28a of the second ply 28. Based on the included carcass cord 54, this second tilt angle β is obtained.

  From the viewpoint that the outer reinforcing layer 42 effectively contributes to the rigidity of the buttress 38 in the stretched environment, in the tire 2, the absolute value of the second inclination angle β is preferably 20 ° or more, and preferably 45 ° or less. In particular, when the absolute value of the second inclination angle β is set to 20 ° or more, the outer reinforcing layer 42 exhibits a large tension in an extended environment. By setting the absolute value of the second inclination angle β to 45 ° or less, the outer reinforcing layer 42 contributes to a large shear rigidity in an extended environment. When the contribution due to the shear stiffness is dominant, better steering stability can be achieved while improving the durability. Therefore, in the tire 2, the absolute value of the second inclination angle β is 35 ° or more. More preferred. More preferably 40 ° or more. Particularly preferably, the absolute value of the second inclination angle β is set to 45 °.

  In the tire 2, the absolute value of the first inclination angle α is preferably equal to the absolute value of the second inclination angle β. Thereby, the intermediate part for formation of the inner side reinforcement layer 40 and the outer side reinforcement layer 42 can be made common, and the fall of productivity can be prevented. From the viewpoint of productivity, steering stability and wear resistance, in the tire 2, the inclination direction of the first reinforcement cord 52a with respect to the carcass cord 54 is opposite to the inclination direction of the second reinforcement cord 52b with respect to the carcass cord 54. In addition, the absolute value of the first inclination angle α is more preferably equal to the absolute value of the second inclination angle β.

  In the manufacture of the tire 2, a plurality of rubber members are assembled to obtain a raw cover (unvulcanized tire 2). This raw cover is put into a mold. The outer surface of the raw cover is in contact with the cavity surface of the mold. The inner surface of the raw cover contacts the bladder or the core. The raw cover is pressurized and heated in the mold. The rubber composition of the raw cover flows by pressurization and heating. The rubber causes a crosslinking reaction by heating, and the tire 2 is obtained. An uneven pattern is formed on the tire 2 by using a mold having an uneven pattern on the cavity surface.

  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 case of the passenger car tire 2, the dimensions and angles are measured in a state where the internal pressure is 180 kPa. The same applies to pneumatic tires according to other embodiments described later.

  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.

  In the present specification, the normal load means a load defined in a standard on which the tire 2 depends. “Maximum value” published in “Maximum load capacity” in the JATMA standard, “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, and “LOAD CAPACITY” in the ETRTO standard are normal loads.

  FIG. 3 shows a part of a pneumatic tire 62 according to another embodiment of the present invention. In FIG. 3, the vertical direction is the radial direction of the tire 62, the horizontal direction is the axial direction of the tire 62, and the direction perpendicular to the paper surface is the circumferential direction of the tire 62.

  The tire 62 has the same configuration as the tire 2 shown in FIG. 1 except for the carcass 64. Therefore, in FIG. 2, the same members as those of the tire 2 of FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  In the tire 62, the carcass 64 includes a first ply 66 and a second ply 68. The first ply 66 and the second ply 68 are bridged between the beads 8 on both sides, and extend along the inside of the tread 4 and the sidewall 6.

  Although not shown, each of the first ply 66 and the second ply 68 includes a plurality of carcass cords arranged in parallel, as in the first ply 26 and the second ply 28 in the carcass 10 of the tire 2 shown in FIG. And topping rubber. The absolute value of the angle formed by each carcass cord with respect to the equator plane is 75 ° to 90 °. The carcass 64 has a radial structure. 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 first ply 66 is folded around the core 22 from the inner side to the outer side in the axial direction. By this folding, the first ply 66 is formed with a first main portion 66a and a pair of first folding portions 66b. In other words, the first ply 66 includes a first main portion 66a and a pair of first folded portions 66b. The first main portion 66 a bridges between the core 22 of one bead 8 and the core 22 of the other bead 8. Each first folded portion 66b extends from the core 22 substantially outward in the radial direction.

  The second ply 68 is folded around the core 22 from the inner side to the outer side in the axial direction. By this folding, the second ply 68 is formed with a second main portion 68a and a pair of second folding portions 68b. In other words, the second ply 68 includes a second main portion 68a and a pair of second folded portions 68b. The second main portion 68 a bridges between the core 22 of one bead 8 and the core 22 of the other bead 8. Each second folded portion 68b extends from the core 22 substantially outward in the radial direction.

  In the tire 62, the end 70 of the first folded portion 66b is located inside the end 72 of the second folded portion 68b in the radial direction.

  As shown in FIG. 3, in the tire 62, the end 72 of the second folded portion 68 b is sandwiched between the second main portion 68 a and the outer reinforcing layer 42. Unlike the portion of the end 32 of the second folded portion 28b in the tire 2 shown in FIG. 1, the portion of the end 72 of the second folded portion 68b is laminated outside the second main portion 68a.

  In the tire 62, as described in the tire 2 shown in FIG. 1, the reinforcing portion 18 disposed in the buttress 38 includes the inner reinforcing layer 40 and the outer reinforcing layer 42. The inner reinforcing layer 40 is located inside the carcass 64, and the outer reinforcing layer 42 is located outside the carcass 64. The inner reinforcing layer 40 includes a first reinforcing cord 52a extending at an inclination with respect to the carcass cord, and the outer reinforcing layer 42 includes a second reinforcing cord 52b extending at an inclination with respect to the carcass cord. It is out.

  In the tire 62, the inner reinforcing layer 40 contributes to the rigidity of the tire 62 in one buttress 38 positioned on the outer side in the turning state, and the outer reinforcing layer 42 is provided on the tire 62 in the other buttress 38 positioned on the inner side in the turning. Contributes to the rigidity of In other words, in the tire 62, the reinforcing portion 18 provided in each of the left and right buttresses 38 effectively contributes to improving the rigidity of the tire 62. In the tire 62, even in the buttress 38 on which a load is placed during turning, the reinforcing portion 18 can sufficiently exhibit its function. In the tire 62, improvement in steering stability is achieved.

  In the tire 62, the rigidity of each of the left and right buttresses 38 is improved. In the tire 62, the difference in rigidity between the left and right buttresses 38 is small in the turning state. Since the sliding of the tread surface 20 with respect to the road surface is suppressed, the tire 62 is less likely to be unevenly worn. In the tire 62, good wear resistance is maintained.

  As is apparent from the above description, in the tire 62 as well, as in the case of the tire 2 shown in FIG. 1, improvement in steering stability is achieved without impairing wear resistance.

  As described above, in the tire 62, the end 72 of the second folded portion 68b is sandwiched between the second main portion 68a and the outer reinforcing layer 42. The portion of the end 72 of the second folded portion 68b is not laminated on the outer side of the outer reinforcing layer 42 as the portion of the end 32 of the second folded portion 28b in the tire 2 shown in FIG. In the tire 62, the contribution of the second folded portion 68b to the shear rigidity is lower than that of the second folded portion 28b in the tire 2 shown in FIG. The rigidity of the buttress 38 of the tire 62 is slightly smaller than that of the tire 2 shown in FIG. In other words, the rigidity of the buttress 38 of the tire 62 is mild. The tire 62 is excellent in ride comfort. From this point of view, when ride comfort is important, the end 72 of the second folded portion 68b is located between the second main portion 68a and the outer reinforcing layer 42 as in the tire 62 shown in FIG. It is preferable to be sandwiched.

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

[Example 1]
A tire having the configuration shown in FIG. 1 was produced. The size of this tire is 255 / 40R18. The specifications of the reinforcing part in Example 1 are as shown in Table 1 below. In Example 1, a part of the second folded portion of the second carcass ply is laminated on the outside of the outer reinforcing layer. The end of the second folded portion is arranged in the radial direction between the inner end of the inner reinforcing layer and the outer end thereof, specifically, near the radial center position of the inner reinforcing layer. The end of the second folded portion is separated from the inner end of the inner reinforcing layer by 3 mm or more and from the outer end of the inner reinforcing layer by 3 mm or more. In Example 1, a cord made of aramid fiber (structure = 1670 dtex / 2) was used for the first reinforcing cord of the inner reinforcing layer and the second reinforcing cord of the outer reinforcing layer. As the carcass cord of the carcass, a cord made of polyester fiber (structure = 1670 dtex / 2) was used. The absolute value of the angle formed by the carcass cord with respect to the equator plane was set to 88 °.

[Comparative Example 1]
A tire of Comparative Example 1 was obtained in the same manner as Example 1 except that the reinforcing portion was not provided.

[Comparative Example 2]
A tire of Comparative Example 2 was obtained in the same manner as in Example 1 except that the reinforcing part was composed of one outer reinforcing layer. In Comparative Example 2, the angle formed by the reinforcing cord with respect to the carcass cord was set to −30 ° (degrees). The inclination direction of the reinforcement cord with respect to the carcass cord is the same as the inclination direction of the second reinforcement cord in the outer reinforcement layer in the first embodiment. The overlap length between the outer reinforcing layer and the belt was set to 6 mm. The overlapping length between the outer reinforcing layer and the bead was set to 6 mm.

[Comparative Example 3]
A tire of Comparative Example 3 was obtained in the same manner as in Example 1 except that the reinforcing part was composed of two outer reinforcing layers. Hereinafter, of the two outer reinforcing layers, the outer reinforcing layer positioned inside is referred to as a first outer reinforcing layer, and the outer reinforcing layer positioned outside is referred to as a second outer reinforcing layer.

  In Comparative Example 3, the angle formed by the reinforcing cord in the first outer reinforcing layer with respect to the carcass cord was set to -20 °. The inclination direction of the reinforcement cord with respect to the carcass cord is the same as the inclination direction of the second reinforcement cord in the outer reinforcement layer in the first embodiment. The angle formed by the reinforcing cord in the second outer reinforcing layer with respect to the carcass cord was set to 30 °. The inclination direction of the reinforcing cord with respect to the carcass cord is opposite to the inclination direction of the reinforcing cord with respect to the carcass cord in the first outer reinforcing layer.

  Furthermore, in this comparative example 3, the reinforcement part was comprised so that the 2nd outer side reinforcement layer might become longer than the 1st outer side reinforcement layer located inside this 2nd outer side reinforcement layer. The separation distance between the first outer reinforcing layer and the belt was set to -3 mm. The separation distance between the first outer reinforcing layer and the bead was set to -3 mm. The overlapping length between the second outer reinforcing layer and the belt was set to 6 mm. The overlapping length between the second outer reinforcing layer and the bead was set to 6 mm.

[Example 2]
The angle α that the first reinforcing cord in the inner reinforcing layer makes with the carcass cord and the angle β that the second reinforcing cord in the outer reinforcing layer makes with the carcass cord are as shown in Table 1 below. The tire of Example 2 was obtained in the same manner as Example 1. In Example 2, the inclination direction of the first reinforcement cord with respect to the carcass cord is the same as the inclination direction of the second reinforcement cord with respect to the carcass cord.

[Example 3]
The tire of Example 3 is the same as Example 1 except that the tire is configured as shown in FIG. 3, that is, the end of the second folded portion is sandwiched between the second main portion and the outer reinforcing layer. Got.

[Example 4-7]
The angle α formed by the first reinforcing cord with respect to the carcass cord in the inner reinforcing layer and the angle β formed with the second reinforcing cord with respect to the carcass cord in the outer reinforcing layer were performed as shown in Table 2 below. In the same manner as in Example 1, the tire of Example 4-7 was obtained.

[Example 8]
The distance UB between the inner reinforcing layer and the belt, the distance UA between the inner reinforcing layer and the bead, the overlapping length SB between the outer reinforcing layer and the belt, and the overlapping length SA between the outer reinforcing layer and the bead. A tire of Example 8 was obtained in the same manner as Example 1 except that it was as shown in Table 2 below. In Example 8, the inner reinforcing layer is longer than the outer reinforcing layer.

[Examples 9-12]
The tires of Examples 9-12 were the same as Example 1 except that the separation distance UB between the inner reinforcement layer and the belt and the separation distance UA between the inner reinforcement layer and the bead were as shown in Table 3 below. Got. In Example 9, the inner reinforcement layer overlaps the belt and bead.

[Examples 13-16]
Example 13-16 is the same as Example 1 except that the overlapping length SB of the outer reinforcing layer and the belt and the overlapping length SA of the outer reinforcing layer and the bead are as shown in Table 4 below. Tires.

[Steering stability]
The tire was incorporated into a regular rim (19 × 8 J), and the tire was filled with air so that the internal pressure was 240 kPa. This tire was mounted on a rear-wheel drive sports car equipped with a turbocharged engine having a displacement of 2000 cc. A professional test driver drove this sports car on the racing circuit and evaluated the handling stability. The results are shown in Tables 1-4 below as indices. Larger numbers are preferable.

[Abrasion resistance]
The tire was incorporated into a regular rim (19 × 8 J), and the tire was filled with air so that the internal pressure was 240 kPa. This tire was mounted on a rear-wheel drive sports car equipped with a turbocharged engine having a displacement of 2000 cc. I have a professional test driver drive this sports car. After traveling 6000 km in the city area and 4000 km on the highway, the amount of wear at the shoulder portion of the tire was measured. The results are shown in Tables 1-4 below as indices. The larger the value, the smaller the amount of wear and the better.

  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 technology related to the reinforcing portion described above can be applied to various types of tires.

2, 62 ... tire 4 ... tread 6 ... sidewall 8 ... bead 8a ... outer end of bead 8 10, 64 ... carcass 12 ... belt 12a ... belt 12 End 16 ... Inner liner 18 ... Reinforcement part 20 ... Tread surface 22 ... Core 24 ... Apex 26 ... First carcass ply (first ply)
26a ... 1st main part 26b ... 1st folding | turning part 28 ... 2nd carcass ply (2nd ply)
28a ... second main portion 28b ... second folded portion 30 ... end of first folded portion 26b 32 ... end of second folded portion 28b 38 ... buttress 40 ... inner reinforcing layer 42 ... Outer reinforcing layer 44 ... Outer end of inner reinforcing layer 40 46 ... Inner end of inner reinforcing layer 40 48 ... Outer end of outer reinforcing layer 42 50 ... Outer of outer reinforcing layer 42 End 52, 52a, 52b ... Reinforcement cord 54 ... Carcass cord 66 ... First ply 66a ... First main portion 66b ... First folded portion 68 ... Second ply 68a ... Second main portion 68b ... second folded portion 70 ... end of first folded portion 66b 72 ... end of second folded portion 68b

Claims (8)

It includes a tread, a pair of sidewalls, a pair of beads, a carcass, a belt, an inner liner, and a pair of reinforcing portions.
Each sidewall extends substantially inward in the radial direction from the end of the tread,
Each bead is located radially inward from the sidewall,
The carcass has a radial structure, and is bridged between one bead and the other bead along the inside of the tread and the sidewall,
The belt is laminated with the carcass radially inside the tread;
The inner liner is located inside the carcass;
Each reinforcement is located in a region where the tread transitions from the tread to the sidewall,
The carcass includes a carcass ply, the carcass ply includes a carcass cord,
The reinforcing part includes an inner reinforcing layer and an outer reinforcing layer,
The inner reinforcing layer is located between the inner liner and the carcass ply, and the outer reinforcing layer is located between the carcass ply and the sidewall;
The inner reinforcing layer includes a first reinforcing cord, and the first reinforcing cord is inclined with respect to the carcass cord;
The pneumatic tire, wherein the outer reinforcing layer includes a second reinforcing cord, and the second reinforcing cord is inclined with respect to the carcass cord.   The outer end of the outer reinforcing layer is located radially outside the outer end of the inner reinforcing layer, and the inner end of the outer reinforcing layer is located radially inward of the inner end of the inner reinforcing layer. The pneumatic tire according to claim 1.   The outer end of the outer reinforcing layer is located between the carcass and the belt, and the inner end of the outer reinforcing layer is located inside the outer end of the bead in the radial direction. Or the pneumatic tire of 2.   The outer end of the inner reinforcing layer is located inside the end of the belt in the radial direction, and the inner end of the inner reinforcing layer is located outside the outer end of the bead in the radial direction. Item 4. The pneumatic tire according to any one of Items 1 to 3. The carcass ply includes a main portion and a pair of folded portions,
The main portion spans between one bead and the other bead, and each folded portion extends substantially outward in the radial direction from the bead,
The pneumatic tire according to any one of claims 1 to 4, wherein the folded portion is laminated outside the outer reinforcing layer.   The pneumatic tire according to any one of claims 1 to 5, wherein an inclination direction of the first reinforcing cord with respect to the carcass cord is opposite to an inclination direction of the second supply cord with respect to the carcass cord. The absolute value of the first inclination angle α formed by the first reinforcing cord with respect to the carcass cord is 20 ° or more and 45 ° or less,
The pneumatic tire according to any one of claims 1 to 6, wherein an absolute value of a second inclination angle β formed by the second reinforcement cord with respect to the carcass cord is 20 ° or more and 45 ° or less.   The pneumatic tire according to claim 7, wherein an absolute value of the first inclination angle α is equal to an absolute value of the second inclination angle β.

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