JP2016040144A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire in which a rigidity of a side wall is increased while increase of a rigidity of a tread being suppressed.SOLUTION: A tire 2 is equipped with a carcass 10, and a reinforcement filler 18. The carcass 10 is equipped with a first carcass ply 28. The first carcass ply 28 is folded around a core 24 from an axial direction inner side to an axial direction outer side. By this folding, a primary part 28a and a folding part 28b are formed on the carcass ply 28. A radial direction outer end of the folding part 28b is laminated on a belt 12 inside a tread 4. The reinforcement filler 18 is laminated on an axial direction outer side of the carcass 10. A radial direction inner end 18a of the reinforcement filler 18 is positioned on an axial direction outer side of an apex 26. An outer end 18b of the reinforcement filler is laminated on the belt 12 inside the tread 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire.

  On an unpaved road, the vehicle may travel on a saddle. The tire wall abuts against the wall surface of the heel. The side wall may be damaged by coming into contact with the heel. In vehicles such as rally and dirt trials, grip performance is also required for the tire surface that contacts the wall surface of the bag. From these viewpoints, the sidewall is required to have high rigidity.

  A vehicle traveling on a paved road requires high cornering power in order to turn faster. On the paved road surface, the cornering power at a low load increases by lowering the tire air pressure. However, when the air pressure is lowered, the cornering power at a high load is lowered. By improving the rigidity of the sidewall, it is possible to suppress a decrease in cornering power under a high load even if the tire air pressure is lowered.

  In particular, the minimum ground clearance of a vehicle is specified for a racing vehicle or the like traveling on a paved road. If the air pressure is lowered, the minimum ground clearance may be exceeded. For this reason, it is necessary to set the initial vehicle height higher than usual. Setting the vehicle height high is disadvantageous from the viewpoint of obtaining downforce. From these viewpoints, high rigidity is required for the sidewall even in a tire traveling on a paved road. By improving the rigidity of the sidewall, even if the air pressure is lowered, the minimum ground clearance can be met without increasing the vehicle height.

  Improvement of the rigidity of these sidewalls can be achieved by increasing the number of carcass plies than usual.

JP 2010-155503 A JP 2000-1773388 A

  Increasing the number of carcass plies increases the rigidity of the tread as well as the sidewalls. If the rigidity of the tread becomes too high, grip performance will be impaired. It is not easy to suppress the rigidity of the tread from becoming too high while improving the rigidity of the sidewall.

  An object of the present invention is to provide a pneumatic tire in which the rigidity of a sidewall is increased while suppressing an increase in the rigidity of a tread.

  The pneumatic tire according to the present invention includes a tread, a pair of sidewalls, a pair of beads, a carcass, a belt, and a reinforcing filler. The tread includes a tread surface that contacts the road surface. 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 is stretched 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 bead includes a core and an apex extending radially outward from the core. The carcass includes a first carcass ply. The first carcass ply is folded from the inner side in the axial direction to the outer side around the core. By this folding, a main portion and a folded portion are formed in the carcass ply. The radially outer end of the folded portion is laminated on the belt inside the tread. The reinforcing filler is laminated outside the carcass in the axial direction. In the radial direction, the inner end of the reinforcing filler is located outside the apex in the axial direction. The outer end of the reinforcing filler is laminated on the belt inside the tread. The reinforcing filler includes a filler cord and a topping rubber.

  Preferably, the filler cord is made of an aramid fiber.

  In one preferable pneumatic tire according to the present invention, the belt includes an inner layer stacked on the carcass and an outer layer stacked on the radially outer side of the inner layer. The outer end portion of the inner layer extends radially inward along the carcass. The radial height Hb from the tread surface to the outer end thereof on the equator plane is set to be 0.2 times or more of the height H when the tire height H is set. The carcass includes a second carcass ply. The second carcass ply is laminated on the first carcass ply. The second carcass ply is folded from the inner side in the axial direction to the outer side around the core. A main part and a folded part are formed by this folding. The outer end in the radial direction of the folded portion is laminated on the outer layer of the belt inside the tread.

  Preferably, the belt includes a belt cord and a topping rubber. The belt cord extends at an angle of 20 ° to 45 ° with respect to the radial direction when viewed in the axial direction. The filler cord of the reinforcing filler extends at an angle of 45 ° or more and 90 ° or less with respect to the radial direction when viewed in the axial direction. The belt cord and the filler cord cross each other.

  Preferably, a longitudinal groove extending in the circumferential direction and a lateral groove extending in the axial direction are formed on the tread surface. The tread is partitioned into a plurality of blocks by vertical grooves and horizontal grooves. A shoulder block arranged in the circumferential direction is formed between the grounding outer end in the axial direction of the tread surface and a vertical groove located on the axially inner side of the grounding outer end and closest to the grounding outer end. The shoulder block includes a protruding portion that protrudes radially inward and axially outward from the grounded outer end. The protruding portion includes a protruding upper wall surface extending inwardly from the radially outer side toward the axially outward side from the grounded outer end, and a radially inner side from the protruding end that is the axially outer end of the protruding upper wall surface. And a protruding lower side wall surface that extends toward the outer surface of the side wall. The lateral groove that defines the shoulder block opens outward in the axial direction on the protruding lower wall surface. In the cross section perpendicular to the circumferential direction, the protruding upper wall surface extends at an angle of 35 ° to 45 ° with respect to the radial direction.

  In another preferable pneumatic tire according to the present invention, the carcass includes a third carcass ply and a fourth carcass ply. The third carcass ply and the fourth carcass ply are stacked on the radially outer side of the first carcass ply. Each of the third carcass ply and the fourth carcass ply is folded back from the outside in the axial direction to the inside around the core. A main part and a folded part are formed by this folding. The outer end of the reinforcing filler positioned inside when mounted on the vehicle is laminated between the inner layer and the outer layer of the belt.

  Preferably, the tire includes a reinforcing rubber layer. The reinforcing rubber layer is located on the radially inner side of the outer core when mounted on the vehicle. This reinforcing rubber layer is laminated between the first carcass ply and the third carcass ply. This reinforcing rubber layer extends from the inner end to the outer end of the core in the axial direction.

  Preferably, the folded end of the folded portion of the third carcass ply is located radially inward from the folded end of the folded portion of the fourth carcass ply. The distance in the radial direction from the folded end of the third carcass ply to the bead toe is 10 mm or more and 15 mm or less. The radial distance from the folded end of the fourth carcass ply to the folded end of the third carcass ply is 5 mm or more and 10 mm or less.

  Preferably, each of the first carcass ply, the third carcass ply, and the fourth carcass ply includes a carcass cord and a topping rubber. The carcass cord extends while being inclined with respect to the equator plane. The inclination angle formed by the carcass cord and the equator plane is set to 40 ° or more and 70 ° or less.

  Preferably, the tire is used at an air pressure of 60 kPa to 70 kPa.

  In the pneumatic tire according to the present invention, the rigidity of the sidewall is improved. In this tire, the rigidity of the tread is prevented from becoming too high while the rigidity of the sidewall is improved. This tire effectively improves the rigidity of the sidewall while ensuring the grip performance of the tread.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an explanatory view showing a part of the tread of the tire of FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view showing a part of a pneumatic tire according to another embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view showing a part of the tire of FIG. 6 is an enlarged cross-sectional view showing another part of the tire of FIG. It is explanatory drawing by which the use condition of the tire of FIG. 4 was shown.

  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 clinch 7, a pair of beads 8, a carcass 10, a belt 12, a band 14, an inner liner 16, and a pair of reinforcing fillers 18. The tire 2 is a tubeless type. The tire 2 is attached to a vehicle such as a four-wheeled vehicle. The tire 2 is attached to a vehicle such as a rally or a dirt trial, for example.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 20 that contacts the road surface. Although not shown, the tread 4 has a base layer and a cap layer. The cap layer is located on the radially outer side of the base layer. The cap layer is laminated on the base layer. The base layer is made of a crosslinked rubber having excellent adhesiveness. A typical base rubber for the base layer is natural rubber. The cap layer is made of a crosslinked rubber having excellent wear resistance, heat resistance and grip properties.

  Each sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. A radially outer end of the sidewall 6 is joined to the tread 4. The radially inner end of the sidewall 6 is joined to the clinch 7. This sidewall 6 is made of a crosslinked rubber having excellent cut resistance and weather resistance. The sidewall 6 prevents the carcass 10 from being damaged.

  Each clinch 7 is located substantially inside the sidewall 6 in the radial direction. The clinch 7 is located outside the beads 8 and the carcass 10 in the axial direction. The clinch 7 is made of a highly hard crosslinked rubber having excellent wear resistance. The clinch 7 is in contact with the flange of the rim. The clinch 7 includes a rib 22. The rib 22 protrudes outward in the axial direction. The rib 22 prevents damage to the flange of the rim on which the tire 2 is mounted. The rib 22 may be formed on the sidewall 6 or may be formed across the sidewall 6 and the clinch 7.

  Each bead 8 is located inside the clinch 7 in the axial direction. The bead 8 is located inside the sidewall 6 in the radial direction. The bead 8 includes a core 24 and an apex 26 that extends radially outward from the core 24. The core 24 has a ring shape and includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 26 is tapered outward in the radial direction. The apex 26 is made of a highly hard crosslinked rubber.

  In the core 24, one or a plurality of wires are formed in a ring shape with a predetermined number of lines in the axial direction and a predetermined number of piles in the radial direction. As shown in FIG. 1, the cross-sectional shape of the core 24 is substantially rectangular. The structure including the core 24 is referred to as a strand bead structure. The so-called single winding bead structure and the tape bead structure are both a kind of strand bead structure.

  The carcass 10 includes a first ply 28 as a first carcass ply and a second ply 30 as a second carcass ply. The first ply 28 and the second ply 30 are bridged between the beads 8 on both sides, and extend along the tread 4 and the sidewall 6. The first ply 28 is folded around the core 24 from the inner side toward the outer side in the axial direction. By this folding, the main portion 28a and the folding portion 28b are formed in the first ply 28. The folded portion 28 b extends to the inner side in the radial direction of the tread 4. The outer end 28 c of the folded portion 28 b is located on the inner side in the radial direction of the tread 4. The outer end 28 c is laminated on the belt 12. The second ply 30 is folded around the core 24 from the inner side toward the outer side in the axial direction. By this folding, the main portion 30a and the folding portion 30b are formed in the second ply 30. The folded portion 30 b extends to the inner side in the radial direction of the tread 4. The outer end 30 c of the folded portion 30 b is located on the inner side in the radial direction of the tread 4. The outer end 30 c is laminated on the belt 12. The outer end 30c is located on the outer side in the axial direction from the outer end 28c. Due to the first ply 28 and the second ply 30, the carcass 10 has a so-called ultra high turn-up structure (UHTU structure).

  Each of the first ply 28 and the second ply 30 includes a large number of carcass cords and topping rubbers arranged in parallel. The absolute value of the angle formed by each carcass cord with respect to the equator plane is 75 ° to 90 °. In other words, the carcass 10 has a radial structure. The cord is made of organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. The carcass 10 may be formed from a single ply.

  The belt 12 is located between the tread 4 and the sidewall 6 and the carcass 10. The belt 12 is laminated with the carcass 10. The belt 12 reinforces the carcass 10. The belt 12 includes an inner layer 32 and an outer layer 34. The inner layer 32 and the outer layer 34 extend along the tread 4. An axial end 32 a of the inner layer 32 extends to the inner side of the sidewall 6 in the axial direction. The inner layer 32 is located between the tread 4 and the sidewall 6 and the carcass 10. An axial end portion 34 a of the outer layer 34 is located on the radially inner side of the tread 4. The outer layer 34 is located between the tread 4 and the carcass 10. Although not shown, each of the inner layer 32 and the outer layer 34 is composed of a large number of belt cords and topping rubbers arranged in parallel. Each belt cord is inclined with respect to the equator plane. A general absolute value of the inclination angle on the equator plane is 10 ° or more and 35 ° or less. The belt cord of the inner layer 32 is inclined with respect to the radial direction inside the sidewall 6 when viewed in the axial direction. The absolute value of this inclination angle is 20 ° or more and 45 ° or less. The inclination direction of the belt cord of the inner layer 32 with respect to the equator plane is opposite to the inclination direction of the belt cord of the outer layer 34 with respect to the equator plane. Steel or organic fiber is used for the material of the belt cord. The belt cord of the inner layer 32 is preferably an organic fiber, and particularly preferably an aramid fiber. The axial width of the outer layer 34 is preferably 0.7 times or more the maximum width of the tire 2. The axial width of the outer layer 34 is preferably 0.75 times or less. The belt 12 may include three or more layers.

  The band 14 is located outside the belt 12 in the radial direction. In the axial direction, 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. 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 14 is restrained by this cord, lifting of the belt 14 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 belt 12 and the band 14 constitute a reinforcing layer 36. The reinforcing layer 36 may be formed only from the belt 12.

  The inner liner 16 is located inside the carcass 10. In the vicinity of the equator plane, 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 reinforcing filler 18 is located inside the sidewall 6 in the axial direction. In the tire 2, the reinforcing filler 18 is located on the inner side in the axial direction of the sidewall 6 and the clinch 7. The reinforcing filler 18 extends in the radial direction along the sidewall 6. The reinforcing filler 18 is laminated on the outer side in the axial direction of the carcass 10. The radially inner end 18 a of the reinforcing filler 18 is located on the outer side in the axial direction of the apex 26. The outer end 18 a is located between the apex 26 and the clinch 7. The radially outer end 18 b of the reinforcing filler 18 is located on the radially inner side of the tread 4. The outer end 18 b is laminated on the belt 12 inside the tread 4. The outer end 18 b is laminated between the inner layer 32 and the outer layer 34 of the belt 12.

  The reinforcing filler 18 includes a filler cord and a topping rubber. The filler cord is inclined with respect to the radial direction inside the sidewall 6 when viewed in the axial direction. The absolute value of this inclination angle is not less than 45 ° and not more than 90 °. This filler cord extends across the belt cord of the inner layer 32 of the belt 12. The filler cord is made of an organic fiber. Examples of preferable organic fibers include aramid fibers, nylon fibers, polyester fibers, rayon fibers, and polyethylene naphthalate.

  A solid line BL in FIG. 1 indicates a bead base line. The bead base line is a line that defines a rim diameter (see JATMA) of a regular rim on which the tire 2 is mounted. The bead base line extends in the axial direction. A point Pt indicates an intersection between the tread surface 20 and the equator plane. A double arrow H indicates the height of the tire 2. This height H is measured as a radial distance from the bead base line to the point Pt. A double-headed arrow Hb indicates the radial height from the point Pt to the outer end 32b of the inner layer 32. This height Hb is measured as a radial distance.

  FIG. 2 shows a part of the tread surface 20 of the tire 2. FIG. 2 shows the tread surface 20 viewed inward in the radial direction. FIG. 3 shows a cross section taken along line III-III in FIG.

  The tread surface 20 has a plurality of longitudinal grooves 38c, longitudinal grooves 38m, and longitudinal grooves 38s extending in the circumferential direction. The vertical groove 38 c is located at the center in the axial direction of the tread surface 20. The vertical groove 38 s is located on the outermost side in the axial direction of the tread surface 20. The vertical groove 38m is located between the vertical groove 38c and the vertical groove 38s in the axial direction. The tread surface 20 has a plurality of transverse grooves 40c, transverse grooves 40m, and transverse grooves 40s extending in the axial direction. The lateral groove 40c is located at the center in the axial direction of the tread surface 20, the lateral groove 40s is located at the outermost side in the axial direction, and the lateral groove 40m is located between the lateral groove 40c and the lateral groove 40s in the axial direction.

  The tread 4 is divided into a plurality of center blocks 42c, middle blocks 42m, and shoulder blocks 42s by vertical grooves 38c, vertical grooves 38m, vertical grooves 38s, horizontal grooves 40c, horizontal grooves 40m, and horizontal grooves 40s. The center block 42c is located at the center of the tread 4 in the axial direction. The shoulder block 42s is located on the outermost side of the tread 4 in the axial direction. The middle block 42m is located between the center block 42c and the shoulder block 42s. Each of the center block 42c, the middle block 42m, and the shoulder block 42s is formed side by side in the circumferential direction.

  A point Pe in FIG. 3 indicates an outer ground end in the axial direction when the tread surface 20 is grounded on a flat road surface. An alternate long and short dash line L1 indicates the contour of a conventional tire. In the tire 2, a protruding portion 44 is formed on the shoulder block 42s. The protruding portion 44 is formed to protrude outward in the axial direction from the shoulder block 42s. The point Pp indicates the protruding end. The protruding end Pp is located on the outermost side in the axial direction in the protruding portion 44.

  The protruding portion 44 includes an upper wall surface 46 and a lower wall surface 48. The upper wall surface 46 is an outer wall surface extending from the grounding outer end Pe to the protruding end Pp. The lower wall surface 48 is an outer wall surface extending from the protruding end Pp to the outer surface 6 a of the sidewall 6. The upper wall surface 46 extends from the grounding outer end Pe so as to incline outward in the radial direction and outward from the radial direction. The lower wall surface 48 extends from the protruding end Pp so as to incline inward in the axial direction and inward from the outside in the radial direction.

  3 indicates the inclination angle of the upper wall surface 46 with respect to the radial direction. A double arrow β indicates an angle formed by the upper wall surface 46 and the lower wall surface 48. A double-headed arrow La indicates the protruding width of the protruding portion 44 in the axial direction. A double-headed arrow Lb indicates the protruding height of the protruding portion 44 inward in the radial direction.

  A dotted line 40b in FIG. 3 indicates the bottom surface of the lateral groove 40s. The horizontal groove 40s extends axially outward from the vertical groove 38s. The lateral groove 40s opens in the lower wall surface 48. A double arrow Hg1 indicates the depth of the lateral groove 40s from the tread surface 20 to the bottom surface of the lateral groove 40s. The depth Hg1 is measured as a distance in the vertical direction of the tread surface 20. The depth Hg1 is measured at the center of the tread surface 20 formed by the shoulder block 42s in the axial direction. A double-headed arrow Hg2 indicates the depth of the lateral groove 40s from the upper wall surface 46 to the bottom surface of the lateral groove 40s. This depth Hg <b> 2 is measured as a vertical distance of the upper wall surface 46. The depth Hg2 is measured at an intermediate point between the points Pe and Pp in the cross section shown in FIG.

  In the tire 2, the folded portion 28 b of the first ply 28 extends to the inner side in the radial direction of the tread 4. The outer end of the folded portion 28 b is laminated on the belt 12. The main portion 28a and the folded portion 28b of the first ply 28 are laminated, and the rigidity of the sidewall 6 is improved. By laminating the outer end of the folded portion 28b with the belt 12, a tension acts on the carcass cord of the folded portion 28b in addition to the carcass cord of the main portion 28a when air is filled. By applying tension to the carcass cord, the rigidity of the sidewall 6 can be further improved.

  Since the reinforcing filler 18 is laminated on the outer side in the axial direction of the carcass 10, the reinforcing filler 18 is extended in the radial direction when the sidewall 6 is bent. The filler cord of the reinforcing filler 18 exhibits a high resistance against pulling. Thereby, the bending of the sidewall 6 is suppressed. By providing this reinforcing filler 18, the sidewall 6 is reinforced. The tire 2 can run even at an air pressure lower than the normal internal pressure. From this viewpoint, the filler cord is preferably made of a material that is difficult to extend. The filler cord is preferably, for example, an aramid fiber or a nylon fiber.

  On the other hand, the first ply 28 and the reinforcing filler 18 suppress the increase in the rigidity of the tread 4 while improving the rigidity of the sidewall 6. In the tire 2, the rigidity of the sidewall 6 is improved without impairing the grip performance of the tread 4.

  In the tire 2, the inner layer 32 of the belt 12 extends radially inward along the carcass 10. The end portion 32 a of the inner layer 32 is located on the inner side in the axial direction of the sidewall 6. The inner layer 32 protects the carcass 10 at the radially outer portion of the sidewall 6. Damage to the carcass 10 is suppressed. When the tire 2 travels on the saddle, the surface on the outer side in the axial direction from the grounding outer end Pe of the tread 4, for example, the upper wall surface 46, the lower wall surface 48, or the like contacts the wall surface of the saddle. By providing the inner layer 32, the tire 2 has improved durability when traveling on a saddle. The inner layer 32 improves the rigidity of the sidewall 6 in a range where the inner layer 32 is located. High grip performance and high traction performance can be demonstrated for the wall surface of this bag. From these viewpoints, the height Hb is preferably not less than 0.2 times the tire height H, and more preferably not less than 0.3 times. If the height Hb is too large, the rigidity of the sidewall 6 becomes too large. From this viewpoint, the height Hb is preferably 0.5 times or less, more preferably 0.4 times or less of the tire height H.

  In the tire 2, the folded portion 30 b of the second ply 30 is laminated on the folded portion 28 b of the first ply 28. The folded portion 30 b extends to the inside of the tread 4. Thereby, the rigidity of the sidewall 6 is further improved. On the other hand, compared with the improvement in the rigidity of the sidewall, the increase in the rigidity of the tread 4 is suppressed.

  In the tire 2, the belt cord and the filler cord of the inner layer 32 extend so as to intersect each other on the sidewall 6. The filler cord of the reinforcing filler 18 extends in an inclined manner with respect to the radial direction when viewed in the axial direction. Thereby, the rigidity of the sidewall 6 is further improved. From this viewpoint, the inclination angle of the filler cord of the reinforcing filler 18 is preferably 45 ° or more. This inclination angle is preferably 90 ° or less.

  A protruding portion 44 is formed on the shoulder block 42s. The protruding portion 44 is partitioned by a vertical groove 38s and a horizontal groove 40s. Inside the protruding portion 44, the folded portion 28b of the first ply 28, the folded portion 30b of the second ply 30, the reinforcing filler 18, and the inner layer 32 improve the rigidity. This protruding portion 44 can be grounded to the wall surface of the heel and exhibit high grip performance. The tire 2 can exhibit high traction performance in saddle running.

  The upper wall surface 46 can obtain a wide contact area with the wall surface when traveling on the wall. Thereby, wear of the shoulder block 42s is suppressed. From this viewpoint, it is preferable that the inclination angle α of the upper wall surface 46 is inclined at 35 ° or more. From the same viewpoint, the angle α is preferably inclined at 45 ° or less.

  The tire 2 having a large protruding width La of the protruding portion 44 can exhibit high grip performance and high traction performance with respect to the heel wall surface. From this viewpoint, the width La is preferably 10 mm or more. On the other hand, in the tire 2 having a small width La, the rigidity of the shoulder block 42s is high. When the rigidity of the shoulder block 42s is small, the traction performance is lowered. The shoulder block 42s has high rigidity and can exhibit high traction performance. From this viewpoint, the width La is preferably 15 mm or less.

  The tire 2 in which the protruding height Lb of the protruding portion 44 is large can provide high traction performance with a saddle. From this viewpoint, the protruding height Lb inward in the radial direction is preferably 15 mm or more. On the other hand, even if the height Lb exceeds 30 mm, further improvement in the traction performance on the scissors cannot be expected. This height Lb is preferably 30 mm or less.

  The protruding portion 44 having a large angle β formed by the upper wall surface 46 and the lower wall surface 48 has high rigidity. The high-rigidity protruding portion 44 can exhibit high traction performance. From this viewpoint, the angle β is preferably 110 ° or more. On the other hand, the protruding portion 44 having a small angle β is likely to stick to the wall surface. When the angle β is too large, the sticking to the wall surface of the heel is reduced. The traction performance will not be fully demonstrated. From this viewpoint, the angle β is preferably 130 ° or less.

  The protruding portion 44 having a large depth Hg2 of the lateral groove 40s can exhibit high grip performance with respect to the wall surface of the heel. From this viewpoint, the depth Hg2 is preferably 0.8 times or more, and more preferably 0.9 times or more the depth Hg1 at the tread surface 20. On the other hand, the protruding portion 44 having a small depth Hg2 is excellent in rigidity. If this Hg2 is too deep, the rigidity of the protruding portion 44 is lowered. In the protruding portion 44 whose rigidity is lowered, the traction performance is lowered. From this viewpoint, the depth Hg2 is preferably 1.0 times or less of the depth Hg1.

  FIG. 4 shows a pneumatic tire 52. In FIG. 4, the vertical direction is the radial direction of the tire 52, the horizontal direction is the axial direction of the tire 52, and the direction perpendicular to the paper surface is the circumferential direction of the tire 52. An alternate long and short dash line CL represents the equator plane of the tire 52.

  The tire 52 is attached to a vehicle such as a four-wheeled vehicle. The tire 52 is attached to a racing vehicle or the like traveling on a circuit course on a paved road. Regarding the tire 52, a configuration different from that of the tire 2 will be described. The description of the same configuration as the tire 2 is omitted.

  The tire 52 includes a tread 54, a pair of sidewalls 56, a pair of beads 58, a carcass 60, a belt 62, an edge band 64, an inner liner 66, a reinforcing filler 68r, a reinforcing filler 68h, and a reinforcing rubber layer 70. The tire 2 is a tubeless type.

  The tread 54 forms a tread surface 72. The tread surface 72 has no groove. A groove may be formed in the tread surface 72. Each sidewall 56 extends substantially inward in the radial direction from the end of the tread 54. A radially outer end of the sidewall 56 is joined to the tread 54. Each bead 58 is located radially inside the sidewall 56. The bead 58 includes a core 74 and an apex 76 that extends radially outward from the core 74. The core 74 has a strand bead structure.

  FIG. 5 shows a sidewall 56 located inside the vehicle when mounted on the vehicle. FIG. 5 shows the side wall 56 on the back side when mounted on the vehicle. FIG. 6 shows a side wall 56 positioned outside the vehicle when mounted on the vehicle. FIG. 6 shows the side wall 56 on the front side when mounted on a vehicle. As shown in FIGS. 5 and 6, the shape of the tire 52 is asymmetric with respect to the equatorial plane.

  5 and 6, the carcass 60 includes a first ply 78 as a first carcass ply, a third ply 80 as a third carcass ply, and a fourth ply 82 as a fourth carcass ply. Consists of. The first ply 78, the third ply 80, and the fourth ply 82 are bridged between the beads 58 on both sides, and extend along the tread 54 and the sidewall 56.

  The first ply 78 is folded around the core 74 from the inner side to the outer side in the axial direction. By this folding, the first ply 78 is formed with a main portion 78a and a folding portion 78b. The folded portion 78b extends to the inside of the tread 54 in the radial direction. The outer end 78 c of the folded portion 78 b is located on the inner side in the radial direction of the tread 54. The outer end 78 c is laminated inside the belt 62 inside the tread 54. The tire 52 has a so-called UHTU structure.

  The third ply 80 is folded around the core 74 from the outside in the axial direction to the inside. By this folding, the main portion 80a and the folding portion 80b are formed in the third ply 80. The folded portion 80 b extends to the inner side in the axial direction of the bead 58. The outer end 80 c of the folded portion 80 b is located on the inner side in the axial direction of the core 74. The outer end 80 c may be located on the inner side in the axial direction of the apex 76. The folded portion 80 b is stacked on the main portion 78 of the first ply 78. The fourth ply 82 is folded around the core 74 from the outside in the axial direction toward the inside. By this folding, the main portion 82a and the folding portion 82b are formed in the fourth ply 82. The folded portion 82 b extends to the inner side in the axial direction of the apex 76. The outer end 82c of the folded portion 82b is located radially outward from the outer end 80c. The outer end 82 c is located on the inner side in the axial direction of the apex 76. The folded portion 82b is stacked on the folded portion 80b.

  A double-headed arrow H1 in FIGS. 5 and 6 indicates the height in the radial direction from the tip Pb of the bead toe to the outer end 80c of the folded portion 80b. A double-headed arrow H2 indicates the height from the outer end 80c of the folded portion 80b to the end 82c of the folded portion 82b. The heights H1 and H2 are measured as linear distances in the radial direction in the cross section shown in the figure.

  The belt 62 is located inside the tread 54. The belt 62 is laminated with the carcass 60. The belt 62 reinforces the carcass 60. The belt 62 includes an inner layer 84 and an outer layer 86. The inner layer 84 and the outer layer 86 extend along the tread 54. An axial end 84 a of the inner layer 84 is located on the inner side in the radial direction of the tread 4. An axial end portion 86 a of the outer layer 86 is located on the radially inner side of the tread 4. In the axial direction, the width of the inner layer 84 is slightly larger than the width of the outer layer 86. Although not shown, each of the inner layer 84 and the outer layer 86 is composed of a large number of parallel belt cords and topping rubber. Each belt cord is inclined with respect to the equator plane. A general absolute value of the inclination angle on the equator plane is 10 ° or more and 35 ° or less. The inclination direction of the belt cord of the inner layer 84 with respect to the equator plane is opposite to the inclination direction of the belt cord of the outer layer 86 with respect to the equator plane. A preferred material for the belt cord is steel. An organic fiber may be used for the belt cord. The axial width of the belt 62 is preferably 0.7 times or more the maximum width of the tire 52. The belt 62 may include three or more layers. The belt 62 constitutes a reinforcing layer 88.

  As shown in FIG. 5, the edge band 64 is located on the inner side (back side) when the vehicle is mounted on the vehicle. The edge band 64 is located near the end of the belt 62. The edge band 64 is located outside the belt 62 in the radial direction. Although not shown, the edge band is made of a cord and a topping rubber. The cord is wound in a spiral. This band 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 end of the belt 62 is restrained by this cord, the lifting of the belt 62 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 66 is located inside the carcass 60. In the vicinity of the equator plane, the inner liner 66 is joined to the inner surface of the carcass 60. The inner liner 66 is made of a crosslinked rubber having excellent air shielding properties. A typical base rubber of the inner liner 66 is butyl rubber or halogenated butyl rubber. The inner liner 66 holds the internal pressure of the tire 2.

  On the back side, a reinforcing filler 68r is located. The reinforcing filler 68r is located inside the sidewall 56 in the axial direction. The reinforcing filler 68r extends in the radial direction along the sidewall 56. The reinforcing filler 68r is laminated outside the carcass 60 in the axial direction. The radially inner end 68a of the reinforcing filler 68r is located outside the apex 76 in the axial direction. A radially outer end 68 b of the reinforcing filler 68 r is located on the radially inner side of the tread 54. The outer end 68 b is laminated on the belt 62. The outer end 68 b is laminated between the inner layer 84 and the outer layer 86 of the belt 62.

  The reinforcing filler 68r is made of a filler cord and a topping rubber. The filler cord is made of an organic fiber. Examples of preferable organic fibers include aramid fibers, nylon fibers, polyester fibers, rayon fibers, and polyethylene naphthalate.

  As shown in FIG. 6, the reinforcing filler 68h is located on the outer side (front side) when mounted on the vehicle. In the reinforcing filler 68h, the outer end 68c is laminated on the inner side in the radial direction of the inner layer 84 of the belt 62. Other configurations of the reinforcing filler 68h are the same as those of the reinforcing filler 68r.

  A reinforcing rubber layer 70 is located on the front side. The reinforcing rubber layer 70 is located inside the core 74 in the radial direction. The reinforcing rubber layer 70 extends around the outer side and the inner side of the core 74 in the axial direction. The reinforcing rubber layer 70 is laminated between the first ply 78 and the third ply 80.

  A double arrow Wc in FIG. 6 indicates the axial width of the core 74. A double-headed arrow Wr indicates the axial width of the reinforcing rubber layer 70. The width Wr of the reinforcing rubber layer 70 is larger than the width Wc of the core 74. The outer end in the axial direction of the reinforcing rubber layer 70 is located outside the outer end in the axial direction of the core 74. The inner end in the axial direction of the reinforcing rubber layer 70 is located inside the inner end in the axial direction of the core 74. The reinforcing rubber layer 70 extends from the axially inner end to the outer end of the core 74 in the axial direction. The reinforcing rubber layer 70 is made of a highly hard crosslinked rubber. The reinforcing rubber layer 70 may be made of the same crosslinked rubber as the apex 76. The rubber hardness of the reinforcing rubber layer is preferably 90 or more.

  In the present invention, the rubber hardness is measured with a type A durometer in accordance with the provisions of “JIS K6253”. The durometer is pressed against the cross section shown in the figure, and the hardness is measured. The measurement is made at a temperature of 23 ° C.

  In the tire 52, as in the tire 2, the main portion 78a and the folded portion 78b of the first ply 78 are laminated, and the rigidity of the sidewall 56 is improved. By laminating the outer end 78c of the folded portion 78b on the inner side of the belt 62, when air is filled, a tension acts on the carcass cord of the folded portion 78b in addition to the carcass cord of the main portion 78a. The rigidity of the sidewall 56 is further improved.

  Since the reinforcing filler 68h is laminated on the outer side in the axial direction of the carcass 60, bending of the sidewall 56 is suppressed. By providing the reinforcing filler 68, the sidewall 56 is reinforced. The tire 2 can run even at an air pressure lower than the normal internal pressure. From this viewpoint, the filler cord is preferably made of a material that is difficult to extend. The filler cord is preferably an aramid fiber, for example.

  The first ply 78 and the reinforcing filler 68 improve the rigidity of the sidewall 56. On the other hand, it is suppressed that the rigidity of the tread 54 becomes too high.

  FIG. 7 shows a state in which the tire 52 is mounted on a four-wheel vehicle (not shown). At the time of mounting on the vehicle, the tire 2 is fitted to the rim 90. An arrow IN in FIG. 4 indicates the direction toward the inner side of the vehicle when mounted on the vehicle. The side wall 56 positioned on the arrow IN side is the back side wall 56. An arrow OUT indicates a direction toward the vehicle outer side in a state of being mounted on the vehicle. The side wall 56 positioned on the arrow OUT side is the front side wall 56. A solid line VL in FIG. 7 indicates a vertical line with respect to the road surface.

  What is indicated by a double-headed arrow CA in FIG. 7 is a camber angle. The tire 52 has a camber angle CA and is attached to the vehicle. The camber angle CA is an angle formed by the equator plane of the tire 52 and a vertical line VL perpendicular to the road surface. In FIG. 7, when the equator plane of the tire 52 is inclined inward from the outside of the vehicle from below to above, the camber angle CA is represented by a negative value. When represented by this negative value, the camber angle CA is referred to as a negative camber angle. When the tire 52 is inclined in the axial direction from the lower side to the upper side, the camber angle CA is represented by a positive value. When the camber angle CA is expressed as a positive value, the camber angle CA is referred to as a positive camber angle.

  The tire 52 is mounted at a negative camber angle. The tire 52 mounted with a negative camber angle contributes to an improvement in turning performance in high speed traveling. From this point of view, in general, in a racing vehicle in which high-speed running performance is important, the tire 2 is mounted at a negative camber angle. Thereby, the cornering performance is improved.

  FIG. 7 shows the state of use of the tire during straight running. When traveling straight ahead, in the tire 52, a region inside the tread surface 72 from the outside of the vehicle is mainly grounded. During cornering, the tire 52 is deformed as the lateral force increases, so that the ground contact portion of the tread surface 72 gradually moves outward in the axial direction. In cornering, the ground contact portion of the tread surface 20 shifts from the vehicle inner area to the outer area.

  In the tire 52, the side wall 56 can exhibit high rigidity by including the carcass 60 and the reinforcing filler 68. The tire 52 has high rigidity in turning and can withstand a large lateral force in turning. The tire 52 is suitable for turning at high speed.

  In the tire 52, the third ply 80 and the fourth ply 82 are folded back from the outer side in the axial direction toward the inner side. The main portion 80 a of the third ply 80 and the main portion 82 a of the fourth ply 82 are laminated on the outer side in the axial direction of the first ply 78. The third ply 80 and the fourth ply 82 are folded around the core 74 from the outside in the axial direction to the inside. When the sidewall 6 is bent, the carcass cords of the main portion 80a and the main portion 82a are extended in the radial direction. These carcass cords exhibit a high resistance against pulling. Thereby, the bending of the sidewall 6 is suppressed.

  Since bending of the sidewall 6 is suppressed and high rigidity is exhibited, the tire 2 can support the vehicle even if the air pressure is lower than that of the conventional tire. Even if the air thickness is lowered, it is possible to suppress the decrease in socialization. By keeping the air pressure low, the cornering power at low loads can be improved. Since the sidewall 6 exhibits high rigidity, even if the air pressure is lowered, the cornering power under a high load can be sufficiently exhibited. The tire 52 can exhibit high cornering power in the entire region from low load to high load.

  When the third ply 80 is folded back around the core 74, a high tension is generated in the carcass cord of the main portion 80a with respect to the bending of the sidewall 6. The third ply 80 can exert a high resistance against the bending of the sidewall. From this viewpoint, the radial height H1 from the outer end 80c of the third ply 80 to the bead toe Pb is preferably 10 mm or more. On the other hand, even if the height H1 is increased to a certain extent, the effect of suppressing the bending of the sidewall 6 does not change. This height H1 is preferably 15 mm or less.

  Similar to the third ply 80, the fourth ply 82 is also folded back around the core 74, thereby suppressing the side wall from being bent. On the other hand, if the outer end 80 c of the third ply 80 and the outer end 82 c of the fourth ply 82 are close to each other, damage is likely to occur as a starting point of the outer end 80 c and the fourth ply 82. From the viewpoint of durability of the tire 52, the radial height H2 from the outer end 82c to the outer end 80c is preferably 5 mm or more. Even if the height H2 is increased to some extent, the durability improvement effect of the tire 52 does not change. This height H2 is preferably 10 mm or less.

  From the viewpoint of improving the rigidity of the sidewall 6, each of the carcass cord of the first ply 78, the carcass cord of the third ply 80, and the carcass cord of the fourth ply 82 extends while being inclined with respect to the equator plane, It is preferable that they cross each other. The absolute value of the inclination angle formed between the equator plane and each carcass cord is preferably 40 ° or more. From the same viewpoint, the absolute value of the tilt angle is preferably 70 ° or less.

  In this tire 52, since the rigidity of the sidewall 6 is high, if the air pressure is 60 kPa or more and 70 kPa or less, a longitudinal spring constant equivalent to that of a conventional tire having an air pressure of 160 kPa can be exhibited. The tire 52 can be sufficiently used at a lower air pressure than before.

  The tire 52 can exhibit a high grip force by being used at a low air pressure. By exhibiting a high grip force, a large shearing force acts in the peeling direction between the carcass 60 and the belt 62 during turning. In the tire 52 used at a low air pressure, separation between the carcass 60 and the belt 62 is more likely to occur than in the tire 52 used at a conventional air pressure. This peeling is particularly likely to occur in the region on the back side of the tire 52. In the tire 52, the outer end 68b of the reinforcing filler 68r on the back side is laminated between the inner layer 84 and the outer layer 86. Thereby, peeling of the belt 62 is suppressed. Even if this tire 52 is used at a low air pressure, it is suppressed that durability is impaired.

  In the tire 52 mounted with a negative camber, a region inside the vehicle on the tread surface 72 is mainly grounded. In the axial direction, the tread 54 is greatly deformed on the back side (the inside of the vehicle). In the tire 52, the belt 62 such as a belt edge loose is easily damaged from the front side to the back side. In the tire 52, the edge band 64 is positioned on the front side, and damage to the belt 62 is suppressed.

  In the tire 52, the reinforcing rubber layer 70 is located on the inner side in the radial direction of the core 74 on the front side. In general, in a tire that is mounted with a negative camber and is used at a low air pressure, rim dropping (a phenomenon in which a bead slips from the seat surface of the rim) is likely to occur. The reinforcing rubber layer 74 suppresses the rotation of the front core 74 even at a low air pressure. By providing this reinforcing rubber layer 74, the occurrence of rim dropping due to use at low air pressure is suppressed.

  In the present invention, the dimension and angle of each member of the tire are measured in a state where the tire is incorporated in a regular rim and the tire is filled with air so as to have a regular internal pressure. During the measurement, no load is applied to the tire. In this specification, the normal rim means a rim defined in a standard on which a tire depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In this specification, the normal internal pressure means an internal pressure defined in a standard on which the tire depends. “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 tire having the basic structure of FIGS. 1-3 was prepared. The size of this tire is 205 / 65R15. Table 1 shows the specifications of this tire. “2-UHTU” of “Carcass structure” in Table 1 is composed of two carcass plies, and indicates that these two carcass plies have an ultra high turn-up (UHTU) structure. “Hb / H 0.2” of “Inner layer” in Table 1 indicates that the ratio Hb / H between the height Hb of the inner layer and the tire height H is 0.2. “Outside” of “Position” of the reinforcing filler in Table 1 indicates that the reinforcing filler is positioned on the outer side in the axial direction of the main portion and the folded portion of the car car splice. Further, “middle” of the “outer end position” of the reinforcing filler in Table 1 indicates that the outer end of the reinforcing filler is located between the inner layer and the outer layer of the belt.

[Comparative Example 1]
A tire having a carcass structure, an inner layer, and a reinforcing filler as shown in Table 1 was prepared. “2-HTU” of “Carcass structure” in Table 1 is composed of two carcass plies, and indicates that these two carcass plies have a high turn-up (HTU) structure. The high turn-up structure is a structure in which the folded portion of the carcass ply extends to the outside from the outer end of the apex, but does not extend to the inside of the tread. “Normal” in “Inner layer” in Table 1 is such that the axial width of the inner layer of the belt is slightly larger than the axial width of the outer layer, and the axial end of the inner layer is located inside the tread. It shows that there is. “Outside main part” of “Position” of the reinforcing filler in Table 1 indicates that the reinforcing filler is located between the main part and the folded part of the car car splice. Further, “below” of “outer end position” of the reinforcing filler in Table 1 indicates that the outer end of the reinforcing filler is positioned on the inner side in the radial direction of the belt (inner layer and outer layer).

[Comparative Example 2-4]
A tire was prepared in the same manner as in Comparative Example 1 except that the carcass structure was changed as shown in Table 1.

[Example 2]
A tire was prepared in the same manner as in Example 1 except that the outer end position of the reinforcing filler was set as shown in Table 1.

[Comparative Example 5-6]
A tire was prepared in the same manner as in Example 1 except that the position of the reinforcing filler and the outer end position were as shown in Table 1. “Between main parts” of “position” of the reinforcing filler in Table 1 indicates that the reinforcing filler is located between the main parts of the two car car splices.

[Evaluation of sidewall rigidity]
The tires of Example 1-2 and Comparative Example 1-6 were mounted on a testing machine, and the rigidity of the sidewall was evaluated. This testing machine includes 12 plates arranged along the tread surface of the tire and a rim into which the tire is incorporated. After the tire was incorporated in the rim, the inside of the tire was filled with air, and the internal pressure was 200 kPa. Each plate was brought into contact with the tread surface, and the tread was restrained by these plates. The rim was lowered to be eccentric, and the relationship between the tire deflection and the load due to the eccentricity was measured. The ratio of the change amount of the load to the change amount of the deflection is shown in the following Table 1 as an index value with Example 1 as 100 as a deflection index. These index values indicate that the greater the numerical value, the higher the rigidity.

[Evaluation of tread rigidity]
The tire tread stiffness of Example 1-2 and Comparative Example 1-6 was evaluated. The tire was assembled in the rim and filled with air at an internal pressure of 200 kPa. The tire sidewall was fixed by sandwiching the tire sidewall. A rod was pressed against the tread surface of the tire, and the relationship between the tire deflection and the load was measured. The ratio of the change amount of the load to the change amount of the deflection is shown in the following Table 1 as an index value with Example 1 as 100 as a deflection index. These index values indicate that the greater the numerical value, the higher the rigidity.

[Grip performance evaluation]
These tires were incorporated into regular rims, and the tires were filled with air so that the internal pressure was 200 kPa. This tire was mounted on a race-specific four-wheel drive vehicle having a displacement of 2000 cc (cm ³ ). The driver was driven by this four-wheel drive vehicle, and sensory evaluation was performed. In this sensory evaluation, the four-wheel drive vehicle was driven on an unpaved circuit. The driver evaluated the grip performance. The results are shown in Table 1 below as an index. This index value is an index value with Example 1 as 100 and is shown in Table 1 below. These index values indicate that the grip performance is higher as the numerical value is larger.

[Durability evaluation]
These tires were incorporated into regular rims, and the tires were filled with air so that the internal pressure was 200 kPa. This tire was mounted on a race-specific four-wheel drive vehicle having a displacement of 2000 cc (cm ³ ). This four-wheel-drive vehicle was allowed to travel 5 laps on an unpaved circuit with 2 km per lap. Damage to the sidewall after running was confirmed. The results are shown in Table 1 below as an index. This index value is an index value with Example 1 as 100 and is shown in Table 1 below. These index values indicate that the larger the numerical value, the higher the durability.

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

[Example 9]
A tire having the basic structure shown in FIGS. 4-6 was prepared. The size of this tire is 330 / 710R18. Table 2 shows the specifications of this tire. “1-2” of “Carcass structure” in Table 2 is composed of one carcass ply folded back from the inner side in the axial direction and two carcass plies folded back from the outer side in the axial direction to the outside. The structure is shown. The carcass ply folded back from the inner side in the axial direction had an ultra high turn-up (UHTU) structure. “Lower” and “middle” of “outer end position of reinforcing filler” in Table 2 have the same meaning as in Table 1. The “front side” in Table 2 indicates that it is located outside the vehicle when mounted on the vehicle, and the “back side” indicates that it is located inside the vehicle. “Symmetry” of “front and back symmetrical structure” in Table 2 indicates that the front side and the back side are symmetric, and “asymmetric” indicates that the front side and the back side are asymmetric.

[Example 3]
A tire was obtained in the same manner as in Example 9, except that the carcass structure, the outer end position of the reinforcing filler, and the presence or absence of the high hardness rubber layer were set as shown in Table 2. “2-0” in “Carcass structure” in Table 2 indicates that the carcass ply is folded back from the inner side in the axial direction. The two carcass plies had an ultra high turn-up (UHTU) structure.

[Comparative Example 7]
A tire was obtained in the same manner as in Example 3 except that the reinforcing filler was not provided.

[Example 4-6]
A tire was obtained in the same manner as in Example 3 except that the carcass structure was changed as shown in Table 2. “2-1” of “Carcass structure” in Table 2 includes two carcass plies folded back from the inner side in the axial direction and one carcass ply folded back from the outer side in the axial direction to the outside. The structure is shown. Similarly, “3-0” of “carcass structure” indicates that the carcass ply is folded back from the inner side in the axial direction. In any tire, the carcass ply folded back from the inner side in the axial direction had an ultra high turn-up (UHTU) structure.

[Swivel performance and rigidity]
The tire of Example 3-9 was incorporated into a regular rim, and this tire was filled with air so that the internal pressure was 200 kPa. This tire was mounted on a racing four-wheeled vehicle having a displacement of 3000 cm ³ . The driver drove the four-wheeled vehicle on the paved racing circuit, and the turning performance and the sense of rigidity were sensorially evaluated. The results are shown in Table 2 below as an index. The turning performance was evaluated at a low speed of about 70 km / h and about 100 km / h. These index values are shown in Table 2 below, with the index value of Example 3 being 100. These index values are preferable as the numerical value increases.

[BEL resistance evaluation and rim drop resistance evaluation]
A four-wheeled vehicle equipped with these tires was allowed to run 30 laps on a racing circuit of 3.7 km per lap. A deviation between the bead of the tire after running and the seat surface of the rim was observed. In addition, the tire after running was disassembled, and the presence or absence of peeling of the belt hedge was observed. The evaluation results are shown in Table 2 below as index values with Example 3 as 100. These index values indicate that the larger the numerical value, the higher the evaluation of BEL resistance and rim resistance.

  As shown in Table 2, the tires of the examples are highly evaluated. From this evaluation result, the superiority of the tire of the present invention is clear.

  The method described above can be widely applied to tires mounted on vehicles.

2, 52 ... Tire 4, 54 ... Tread 6, 56 ... Sidewall 7 ... Clinch 8, 58 ... Bead 10, 60 ... Carcass 12, 62 ... Belt 14, .... Bands 16, 66 ... Inner liner 18, 68 ... Reinforcing filler 20, 72 ... Tread surface 24, 74 ... Core 26, 76 ... Apex 28, 78 ... First Ply 30 ... Second ply 32,84 ... Inner layer 34,86 ... Outer layer 36,88 ... Reinforcing layer 38 ... Vertical groove 40 ... Horizontal groove 42 ... Block 44 ..Projected portion 46 ... Upper wall surface 48 ... Lower wall surface 64 ... Edge band 70 ... Reinforcing rubber layer 80 ... Third ply 82 ... Fourth ply

Claims (10)

It has a tread, a pair of sidewalls, a pair of beads, a carcass, a belt and a reinforcing filler,
The tread has a tread surface that contacts the road surface,
Each sidewall extends radially inward from the end of the tread,
Each bead is located radially inside the sidewall,
The carcass is stretched 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 bead includes a core and an apex extending radially outward from the core;
The carcass is provided with a first carcass ply, and the first carcass ply is folded from the inner side to the outer side around the core. As a result, the carcass ply has a main portion and a folded portion. And the outer end in the radial direction of the folded portion is laminated on the belt inside the tread,
The reinforcing filler is laminated on the outside of the carcass in the axial direction, the inner end of the reinforcing filler is located on the outer side of the apex in the radial direction, and the outer end is laminated on the belt inside the tread. ,
A pneumatic tire in which the reinforcing filler includes a filler cord and a topping rubber.   The tire according to claim 1, wherein the filler cord is made of an aramid fiber. An inner layer on which the belt is laminated on the carcass, and an outer layer laminated on the radially outer side of the inner layer,
When the outer end portion of the inner layer extends radially inward along the carcass and the radial height Hb from the tread surface to the outer end of the equatorial plane is the tire height H, this height H is 0.2 times or more,
The carcass includes a second carcass ply, the second carcass ply is stacked on the first carcass ply, and is folded around the core from the inner side to the outer side in the axial direction. The tire according to claim 1 or 2, wherein a main portion and a turned-up portion are formed by, and a radially outer end of the turned-up portion is laminated on an outer layer of the belt inside the tread. The belt includes a belt cord and a topping rubber, and the belt cord extends at an angle of 20 ° to 45 ° with respect to the radial direction when viewed in the axial direction.
The filler cord of the reinforcing filler extends at an angle of 45 ° or more and 90 ° or less with respect to the radial direction when viewed in the axial direction,
The tire according to any one of claims 1 to 3, wherein the belt cord and the filler cord cross each other. A longitudinal groove extending in the circumferential direction and a lateral groove extending in the axial direction are formed on the tread surface,
This tread is partitioned into multiple blocks by vertical and horizontal grooves,
A shoulder block arranged in the circumferential direction is formed between the grounding outer end in the axial direction of the tread surface and the longitudinal groove closest to the grounding outer end located on the axially inner side of the grounding outer end,
The shoulder block has a protruding portion that protrudes radially inward and axially outward from the grounding outer end, and the protruding portion is inclined radially outwardly and inwardly from the grounding outer end toward the axially outward direction. An extended upper wall surface that extends, and a protruding lower wall surface that extends radially inward from the protruding end that is the axially outer end of the protruding upper wall surface and continues to the outer surface of the sidewall,
The lateral groove that defines this shoulder block protrudes outward in the axial direction on the lower side wall surface,
The tire according to any one of claims 1 to 4, wherein in the cross section perpendicular to the circumferential direction, the protruding upper wall surface extends with an inclination of 35 ° or more and 45 ° or less with respect to the radial direction. The carcass includes a third carcass ply and a fourth carcass ply that are stacked on the radially outer side of the first carcass ply, and each of the third carcass ply and the fourth carcass ply has an axis around the core. Folded from the outside to the inside, the main part and the folded part are formed by this folding,
The tire according to claim 1 or 2, wherein an outer end of the reinforcing filler positioned inside when mounted on a vehicle is laminated between an inner layer and an outer layer of the belt. It has a reinforced rubber layer,
When this reinforcing rubber layer is attached to the vehicle, the outer core is positioned on the radially inner side and is laminated between the first carcass ply and the third carcass ply,
The tire according to claim 6, wherein the reinforcing rubber layer extends in an axial direction from an axial inner end to an outer end of the core. The folded end of the folded portion of the third carcass ply is located radially inward from the folded end of the folded portion of the fourth carcass ply;
The radial distance from the folded end of the third carcass ply to the bead toe is 10 mm or more and 15 mm or less,
The tire according to claim 6 or 7, wherein a radial distance from a folded end of the fourth carcass ply to a folded end of the third carcass ply is 5 mm or more and 10 mm or less. Each of the first carcass ply, the third carcass ply and the fourth carcass ply includes a carcass cord and a topping rubber,
This carcass cord extends with an inclination to the equator plane,
The tire according to any one of claims 6 to 8, wherein an inclination angle formed by the carcass cord and the equator plane is 40 ° or more and 70 ° or less.   The tire according to any one of claims 6 to 9, wherein the tire is used at an air pressure of 60 kPa to 70 kPa.

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