JP2014125144A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire having a toe of bead with improved rigidity without deteriorating rim assembling.SOLUTION: A carcass 10 of a tire 2 comprises: a first ply 32; a second ply 34 laminated on outside in a radial direction of the first ply 32; and a third ply 36 laminated on outside in a radial direction of the second ply 34. A chafer 16 is formed of cloth and rubber impregnated in the cloth. The first and second plies 32, 34 are folded from inside to outside in an axial direction around a core 28. The third ply 36 is folded from outside to inside in the axial direction around the core 28. A folding part 36b formed by folding the third ply 36 is laminated on outside in an axial direction of the chafer 16 on inside in the axial direction of the core 28. A reinforcement rubber layer 20 is laminated between the second and third plies 34,36 around the core 28, and extends from inside in the axial direction of the core to outside in the axial direction while passing through inside of the core in the radial direction.

Description

  The present invention relates to a pneumatic tire.

  When the vehicle turns, a lateral force acts on the tire bead. In high-speed turning, this lateral force increases, and the bead portion may be separated from the rim flange. The bead part moves away from the rim flange, the amount of deformation of the tire increases, and the ground contact shape of the tire also becomes uneven. If the grounding shape is uneven, sufficient grip force cannot be exhibited.

  Tires with improved bead and bead toe rigidity have been proposed so that the bead is not separated from the rim flange. By improving the rigidity of the bead portion, the bead portion can be suppressed from separating from the rim flange. Further, by improving the rigidity of the bead toe, it is possible to suppress rotation with the bead toe as a fulcrum. Tires with improved bead and bead toe rigidity can exhibit high grip at high speeds.

JP 2000-177338 A

  In a tire with improved bead portion and bead toe rigidity, it is generally difficult to assemble and remove the rim. Furthermore, in these tires, the bead portion and the bead toe may be damaged when the rim is assembled and removed. Tires with improved bead and bead toe rigidity are inferior in rim assembly and removal, that is, in rim assembly.

  An object of the present invention is to provide a tire in which the rigidity of the bead portion is improved without reducing the rim assembly.

  The pneumatic tire according to the present invention has a tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from the end of the tread, and each positioned radially inward of the sidewalls. A pair of beads, a carcass spanned between one bead and the other bead along the inside of the tread and the sidewall, a chafer located in the vicinity of the bead, and a reinforcing rubber layer ing. The carcass includes a first ply that is radially inward on the equator plane, a second ply that is laminated radially outward of the first ply, and a third ply that is laminated radially outward of the second ply. With ply. This bead has a core. The chafer is composed of a cloth and a rubber impregnated in the cloth. The first ply and the second ply are folded from the inner side in the axial direction to the outer side around the core. The third ply is folded back from the axially outer side toward the inner side around the core. The folded portion of the third ply is laminated on the chafer on the inner side in the axial direction of the core. The reinforcing rubber layer is laminated between the second ply and the third ply around the core, and extends from the inner side in the axial direction of the core to the outer side in the radial direction.

  Preferably, the tire includes a protrusion that is located on the inner side in the axial direction of the bead toe and projects inward in the axial direction. This protrusion is made of a crosslinked rubber.

  Preferably, in the tire, the protrusion is formed in a shape protruding inward in the axial direction with a radius of curvature Rp.

  Preferably, the curvature radius Rp is 2 mm or more and 4 mm or less.

  Preferably, the radial height Hp of the protrusion is 6 mm or more and 10 mm or less.

  Preferably, the axial width Wp of the protrusion is 1 mm or more and 3 mm or less.

  Preferably, the hardness of the crosslinked rubber of the reinforcing rubber layer is 90 or more and 100 or less.

  Preferably, in this tire, the ratio (Wt / Wb) between the bead width Wb and the width Wt from the center of the core to the bead toe is 0.45 or more and 0.55 or less.

  The pneumatic tire according to the present invention improves the rigidity of the bead portion without reducing the rim assembly. This tire is excellent in grip performance in cornering.

FIG. 1 is a cross-sectional view illustrating a tire according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a part of the tire of FIG. FIG. 3 is an explanatory diagram showing a use state of the tire of FIG. 1.

  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 tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a belt 12, an inner liner 14, a chafer 16, a filler portion 18, a reinforcing rubber layer 20, a protrusion 22, and a sealing rib 24. The shape of the tire 2 is substantially symmetric with respect to the equator plane. The tire 2 is a tubeless type. The tire 2 is attached to, for example, a four-wheel automobile for racing. The tire 2 is for a four-wheeled vehicle.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 26 that contacts the road surface. The tread surface 26 has no groove. The tire 2 is a slick tire. A groove may be cut in the tread surface 26 to form a tread pattern.

  The sidewall 6 is made of a crosslinked rubber. A radially outer portion of the sidewall 6 is joined to the tread 4. The sidewall 6 extends from the end of the tread 4 substantially inward in the radial direction. The sidewall 6 is located outside the carcass 10 in the axial direction. The side wall 6 prevents the carcass 10 from being damaged.

  The bead 8 is located inside the sidewall 6 in the radial direction. The bead 8 includes a core 28 and an apex 30 that extends radially outward from the core 28. The core 28 has a ring shape. The core 28 includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 30 is tapered outward in the radial direction. The apex 30 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a carcass ply 32 as a first ply, a carcass ply 34 as a second ply, and a carcass ply 36 as a third ply. The carcass ply 34 is laminated on the outer side in the radial direction of the carcass ply 32 on the equator plane. The carcass ply 36 is laminated on the outer side in the radial direction of the carcass ply 34 at the equator plane. The carcass plies 32, 34, and 36 are spanned between the beads 8 on both sides, and extend along the tread 4 and the sidewall 6. The carcass plies 32 and 34 are folded around the core 28 from the inner side to the outer side in the axial direction. By this folding, main portions 32a and 34a extending between the beads 8 and folded portions 32b and 34b folded around the beads 8 are formed. The carcass ply 36 is folded around the core 28 from the outside in the axial direction toward the inside. The carcass ply 36 is formed with a main portion 36 a extending between the beads 8 and a folded portion 36 b folded around the bead 8.

  Although not shown, each of the carcass plies 32, 34, and 36 includes a plurality of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each 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 belt 12 is located on the inner side in the radial direction than the tread 4. The belt 12 is located on the outer side in the radial direction than the carcass 10. The belt 12 is laminated with the carcass 10. The belt 12 reinforces the carcass 10.

  The belt 12 includes a first layer 38, a second layer 40, and a third layer 42. As shown in FIG. 1, the second layer 40 is laminated on the outer side of the first layer 38 in the radial direction on the equator plane. A third layer 42 is laminated on the outer side in the radial direction of the second layer 40. In the axial direction, the width of the third layer 42 is slightly smaller than the width of the second layer 40. The first layer 38 includes a main portion 38a that extends in the axial direction and a folded portion 38b that is folded back radially outward on the outside in the axial direction and extends inward in the axial direction. A second layer 40 and a third layer 42 are laminated on the main portion 38a. The folded portion 38 b is laminated on the outer side in the radial direction of the second layer 40 and the third layer 42. The main portion 38a and the folded portion 38b sandwich the end portion of the second layer 40 and the end portion of the third layer 42.

  Although not shown, each of the first layer 38, the second layer 40, and the third layer 42 is composed of a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the equator plane. The absolute value of the tilt angle is usually 10 ° or more and 40 ° or less. The direction of inclination of the cord of the first layer 38 with respect to the equator plane is opposite to the direction of inclination of the cord of the second layer 40 with respect to the equator plane. The inclination direction of the cord of the second layer 40 with respect to the equator plane is opposite to the inclination direction of the cord of the third layer 42 with respect to the equator plane. A preferred material for the cord is steel. An organic fiber may be used for the cord. The axial width of the belt 12 is preferably 0.7 times or more the maximum width of the tire. The belt 12 may be composed of one layer, may be composed of two layers, or may be composed of four or more layers.

  The inner liner 14 is located inside the carcass 10. The inner liner 14 covers the inner peripheral surface of the carcass 10. The inner liner 14 is made of a crosslinked rubber. The inner liner 14 is made of rubber having excellent air shielding properties. A typical base rubber of the inner liner 14 is butyl rubber or halogenated butyl rubber. The inner liner 14 maintains the internal pressure of the tire 2.

  As shown in FIG. 2, the chafer 16 is located in the vicinity of the bead 8. The chafer 16 includes a bottom surface portion 16a, an inner surface portion 16b, and an outer surface portion 16c. The bottom surface portion 16 a is located on the radially inner side of the core 28 and extends in a substantially axial direction. The inner surface portion 16b is located on the inner side in the axial direction of the core 28 and extends continuously outward from the inner side in the axial direction of the bottom surface portion 16a. The outer surface portion 16c is located outside the core 28 in the axial direction and extends outward in the radial direction continuously from the outer side in the axial direction of the bottom surface portion 16a. When assembled in the rim, the chafer 16 abuts the rim. The contact of the chafer 16 protects the vicinity of the bead 8. The chafer 16 is made of cloth and rubber impregnated in the cloth. The chafer 16 is a so-called canvas chafer.

  The filler part 18 is located in the vicinity of the bead 8. The filler portion 18 surrounds the bead 8. The filler portion 18 is located between the bead 8 and the carcass ply 32. The filler part 18 reinforces the bead 8. In the tire 2, the filler portion 18 includes a filler 44. The filler 44 is folded around the core 28 from the inner side to the outer side in the axial direction. The filler 44 extends in the radial direction along the carcass ply 32. In the tire 2, the filler 44 is made of a crosslinked rubber. The feeler part 18 is composed of two or more fillers, and two or more fillers may be laminated.

  The reinforcing rubber layer 20 is located in the vicinity of the core 28. The reinforcing rubber layer 20 includes a bottom portion 20a, an inner portion 20b, and an outer portion 20c. The bottom portion 20 a is located on the radially inner side of the core 28. The inner portion 20 b is located on the inner side in the axial direction of the core 28. The inner side portion 20b extends outward in the radial direction continuously from the inner side in the axial direction of the bottom portion 20a. The outer portion 20 c is located on the outer side in the axial direction of the core 28. The outer portion 20c extends outward in the radial direction continuously from the axially outer side of the bottom portion 20a. The reinforcing rubber layer 20 is made of a highly hard crosslinked rubber.

  The reinforcing rubber layer 20 is located around the core 28. The reinforcing rubber layer 20 is located between the carcass ply 34 and the carcass ply 36. The reinforcing rubber layer 20 extends from the inner side in the axial direction of the core 8 to the outer side in the axial direction through the inner side in the radial direction. The bottom portion 20 a is laminated between the carcass ply 34 and the carcass ply 36. The inner portion 20 b is laminated between the folded portion 36 b of the carcass ply 36 and the main portion 34 a of the carcass ply 34. The outer portion 20 c is laminated between the folded portion 34 b of the carcass ply 34 and the main portion 36 a of the carcass ply 36.

  A point Bt in FIG. 2 indicates a bead toe. The protrusion 22 is located on the inner side in the axial direction of the bead toe Bt. The protrusion 22 protrudes inward in the axial direction. This protrusion 22 protrudes continuously in the circumferential direction of the tire. The protrusion 22 is made of a crosslinked rubber. A point Pp indicates the radially outer end of the protrusion 22. The radially inner end of the protrusion 22 is located at the bead toe Bt.

  The sealing rib 24 is formed to protrude from the outer surface portion 16 c of the chafer 16. The sealing rib 24 is formed to project outward from the inner side in the axial direction from the outer side in the radial direction toward the inner side. When the sealing rib 24 is incorporated in the rim, the sealing rib 24 abuts on the radially inner side of the rim flange. The sealing rib 24 contributes to the airtightness of the tire 2 by contacting the rim flange.

  A double arrow Hp in FIG. 2 indicates the height of the protrusion 22 in the radial direction. This height Hp is measured by measuring the distance from the beat toe Bt to the outer end Pp. This height Hp is measured as a linear distance from the beat toe Bt to the outer end Pp. An arrow Rp indicates the radius of curvature of the protrusion 22. The protrusion 22 has a radius of curvature Rp and is formed to protrude inward in the axial direction. A double-headed arrow Wp indicates the width of the protrusion 22 in the axial direction. This width Wp is measured as the distance from the beat toe Bt to the innermost point in the axial direction of the protrusion 22. This width Wp is measured as a linear distance in the axial direction. The height Hp and the width Wp are measured in an unused state before the tire 2 is assembled to the rim.

  Point Bh indicates a bead heel. The bead heel Bh means an intersection where the extension line of the rim base and the extension line of the inner surface of the rim flange intersect. A double-headed arrow Wb indicates the width of the bead portion 46 in the axial direction. The bead width Wb is measured as the distance from the bead heel Bh to the bead toe Bt. The bead width Wb is measured as a linear distance in the axial direction. A double arrow Wt indicates a width from the center of the core 28 to the bead toe Bt. This width Wt is measured as a linear distance in the axial direction. A tire axial line passing through the bead heel Bh is a bead base line BL. The bead width Wb and the width Wt are measured in an unused state before the tire 2 is assembled to the rim.

  FIG. 3 shows a state in which the tire 2 is assembled to the rim 48. The bottom surface portion 16a of the chafer 16 of the tire 2 is mainly in contact with the rim base 48a in the radial direction. The outer surface portion 16c is in contact with the rim flange 48b mainly in the axial direction. During turning, a lateral force indicated by an arrow F acts on the bead portion 46. Due to the action of the lateral force F, the bead portion 46 receives the lateral force F in the direction of rotation about the bead toe Bt.

  Since the tire 2 includes the reinforcing rubber layer 20 around the core 28, the rigidity of the bead portion 46 is improved. Since the reinforcing rubber layer 20 extends from the inner side in the axial direction of the core 28 to the outer side in the radial direction through the inner side in the radial direction, not only the periphery of the bead toe Bt but also the rigidity of the bead portion 46 is improved in a wide range. . From this point of view, the radially outer end of the inner portion 20b of the reinforcing rubber layer 20 and the radially outer end of the outer portion 20c are located at the same position as the radially outer end of the core 28 or radially outward of the core 28. It is preferable to be located outside the end.

  Further, the reinforcing rubber layer 20 is laminated between the carcass ply 34 and the carcass ply 36, and the carcass ply 34 and the carcass ply 36 spanned between the beads 8 sandwich the reinforcing rubber layer 20. In addition to improving the rigidity of the bead part 46 in a wide range, the rigidity of the bead part 46 is further improved. From this point of view, it is preferable that the radially outer end of the inner portion 20b of the reinforcing rubber layer 20 is located radially inward from the radially outer end of the folded portion 36b. In the tire 2, the deformation of the bead portion 46 in a direction away from the rim flange 48 b with respect to the lateral force F is suppressed.

  In the tire 2, since the carcass ply 36 is laminated on the bottom surface portion 16a and the inner surface portion 16b of the chafer 16, the rigidity around the bead toe Bt is improved. Local deformation around the bead toe Bt is suppressed. Since the outer end of the folded portion 36b is positioned radially inward from the outer end of the inner surface portion 16b of the chafer 16, damage to the carcass ply 36 is suppressed. Further, since the carcass ply 36 is laminated on the bottom surface portion 16a and the outer surface portion 16c, the rigidity around the bead heel Bh is improved. Local deformation around the bead heel Bh is suppressed.

  In the tire 2, the carcass ply 36 is laminated on the chafer 16, and the reinforcing rubber layer 20 is sandwiched between the carcass ply 36 and the carcass ply 34, thereby passing from the inner side in the axial direction of the core 28 to the inner side in the radial direction of the core 28. The bead portion 46 extending outward in the axial direction of the core 28 is reinforced. This prevents the bead portion 46 from being damaged when being assembled to the rim 48 and when being removed from the rim 48. Since the bead 46 is hardly damaged, the tire 2 can be easily assembled and removed.

  Further, since the tire 2 includes the protrusion 22 that is located on the inner side in the axial direction of the bead toe Bt and protrudes inward in the axial direction, damage around the bead toe Bt is further suppressed. Since this protrusion 22 protrudes on the outer side in the radial direction of the bead toe Bt, the inhibition of the rim assembly is suppressed.

  From the viewpoint of suppressing damage around the bead toe Bt, it is preferable that the protrusion 22 has a tip shape that protrudes inward in the axial direction with a radius of curvature Rp. From the viewpoint of suppressing damage around the bead toe Bt, the curvature radius Rp is preferably 2 mm or more. On the other hand, a tire having a small curvature radius Rp does not hinder the ease of assembly to the rim 48. In this respect, the curvature radius Rp is preferably 4 mm or less.

  In the tire 2 in which the radial height Hp of the protrusion 22 is high, damage around the bead toe Bt is suppressed. From this viewpoint, the height Hp is preferably 6 mm or more, and more preferably 7 mm or more. On the other hand, the tire 2 having a small height Hp can be easily assembled to the rim 48. From this viewpoint, the height Hp is preferably 10 mm or less, and more preferably 9 mm or less.

  In the tire 2 in which the axial width Wp of the protrusion 22 is large, damage around the bead toe Bt is suppressed. From this viewpoint, the width Wp is preferably 1.0 mm or more, and more preferably 1.5 mm or more. On the other hand, the tire 2 having a small width Wp can be easily assembled to the rim 48. From this viewpoint, the width Wp is preferably 3.0 mm or less, more preferably 2.5 mm or less, and particularly preferably 2.0 mm or less.

  In the tire 2 in which the hardness of the crosslinked rubber of the reinforcing rubber layer 20 is large, the rigidity of the bead portion 46 is improved. From this viewpoint, the hardness of the crosslinked rubber is preferably 90 or more, and more preferably 93 or more. On the other hand, the tire 2 having a low hardness of the crosslinked rubber can be easily assembled to the rim 48. From this viewpoint, the hardness of the crosslinked rubber is preferably 100 or less, and more preferably 98 or less.

  In the tire 2 in which the width Wb of the bead portion 46 is large, the bead 46 is prevented from rotating about the bead toe Bt. Thereby, it is suppressed that the bead part 46 leaves | separates from the rim flange 48b. From this viewpoint, the width Wb is preferably more than 16 mm, and more preferably 18 mm or more. On the other hand, the tire 2 having a small width Wb can be easily assembled to the rim 48. From this viewpoint, the width Wb is preferably 22 mm or less, and more preferably 20 mm or less.

  Further, in the tire 2 having a large ratio (Wt / Wb) between the width Wb of the bead portion 46 and the width Wt from the center of the core 28 to the bead toe Bt, the bead 46 is prevented from rotating about the bead toe Bt. Thereby, it is suppressed that the bead part 46 leaves | separates from the rim flange 48b. From this viewpoint, the ratio (Wt / Wb) is preferably 0.45 or more, and more preferably 0.46 or more. On the other hand, the tire 2 having a small (Wt / Wb) can be easily assembled to the rim 48. From this viewpoint, this (Wt / Wb) is preferably 0.55 or less, more preferably 0.53 or less.

  The rubber hardness referred to in the present invention is measured by pressing a type A durometer against the tire 2 under a condition of 23 ° C. in accordance with the provisions of “JIS-K 6253”.

  In the present invention, unless otherwise specified, 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. 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 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]
The tire shown in FIG. 1 was prepared. The tire size was “255 / 40R18”. As shown in Table 1, this tire was provided with a reinforcing rubber layer. The carcass of this tire was composed of three carcass plies. The values of the radius of curvature Rp, the width Wp, and the height Hp of the protrusions of the tire were as shown in Table 1, respectively. “Yes” in the column of “3 carcass ply folded” in Table 1 indicates that the carcass ply laminated on the outermost side in the radial direction is folded around the core.

[Example 2]
A tire was obtained in the same manner as in Example 1 except that no protrusion was provided.

[Comparative Example 1]
The carcass ply formed of three carcass plies and laminated on the outermost side in the radial direction was not folded back around the core. Other configurations were the same as in Example 1 to obtain a tire. “None” in the column of “3 carcass ply folded” in Table 1 indicates that the carcass ply laminated on the outermost side in the radial direction is not folded around the core.

[Comparative Example 2]
A tire was obtained in the same manner as in Example 1 except that the reinforcing rubber layer was not provided.

[Comparative Example 3]
The carcass ply formed of three carcass plies and laminated on the outermost side in the radial direction was not folded back around the core. Furthermore, this tire was not provided with a reinforcing rubber layer. Other configurations were the same as in Example 1 to obtain a tire.

[Example 3-6]
A tire was obtained in the same manner as in Example 1 except that the radius of curvature Rp of the protrusion and the width Wp of the protrusion were as shown in Table 2.

[Example 7-10]
A tire was obtained in the same manner as in Example 1 except that the width Wp and the height Hp of the protrusions were as shown in Table 3.

[Rim assembly]
These tires were incorporated into a regular rim of “9.0 J × 18 inches”. Thereafter, the tire was removed from the regular rim. The ease of installation and removal work was sensory-evaluated by the operator. The results are shown in Tables 1 to 3 below as indices. This index was indexed with the rim assembly of Example 2 as 100. This index is preferable as the numerical value increases.

[Grip performance]
These tires were incorporated into regular rims, and the tires were filled with air so that the internal pressure was 180 kPa. This tire was mounted on a 4WD vehicle having a displacement of 2000 cm ³ . The driver was allowed to drive this vehicle and sensory evaluation was performed by the driver. In this sensory evaluation, the vehicle was allowed to travel 5 laps on a circuit of 4 km per lap. The driver evaluated the grip performance in turning. The results are shown in Tables 1 to 3 below as indices. This index was indexed with the evaluation result of Example 2 as 100. This index is preferable as the numerical value increases.

  As shown in Tables 1 to 3, in the example tire, the grip performance is improved without significantly impairing the rim assemblage as compared with the tire of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The tire described above can be applied to various vehicles.

DESCRIPTION OF SYMBOLS 2 ... Tire 4 ... Tread 6 ... Side wall 8 ... Bead 10 ... Carcass 12 ... Belt 14 ... Inner liner 16 ... Chafer 18 ... Filler part 20 ... Reinforcing rubber layer 22 ... Protrusion 24 ... Sealing rib 26 ... Tread surface 28 ... Core 30 ... Apex 32, 34, 36 ... Carcass ply 38 ... First Layer 40 ... Second layer 42 ... Third layer 44 ... Filler 46 ... Bead part

Claims (8)

A tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from the end of the tread, a pair of beads each positioned radially inward of the sidewalls, the tread and the above A carcass spanned between one bead and the other bead along the inside of the sidewall, a chafer located in the vicinity of the bead, and a reinforcing rubber layer,
The carcass has a first ply located radially inward on the equator plane, a second ply laminated on the radially outer side of the first ply, and a third ply laminated on the radially outer side of the second ply. Ply and
This bead has a core,
This chafer consists of cloth and rubber impregnated in this cloth,
The first ply and the second ply are folded from the inner side to the outer side around the core, and the third ply is turned from the outer side in the axial direction around the core. The folded back portion of the third ply is laminated on the chafer on the inner side in the axial direction of the core,
A pneumatic tire in which the reinforcing rubber layer is laminated between the second ply and the third ply around the core and extends from the inner side in the axial direction of the core to the outer side in the radial direction. Providing a protrusion that protrudes inward in the axial direction located on the inner side in the axial direction of the bead toe,
The tire according to claim 1, wherein the protrusion is made of a crosslinked rubber.   The tire according to claim 2, wherein the protrusion is formed in a shape protruding inward in the axial direction with a radius of curvature Rp.   The tire according to claim 3, wherein the curvature radius Rp is 2 mm or more and 4 mm or less.   The tire according to any one of claims 1 to 4, wherein a height Hp in the radial direction of the protrusion is 6 mm or more and 10 mm or less.   The tire according to any one of claims 1 to 5, wherein an axial width Wp of the protrusion is 1 mm or more and 3 mm or less.   The tire according to any one of claims 1 to 6, wherein a hardness of the crosslinked rubber of the reinforcing rubber layer is 90 or more and 100 or less.   The tire according to any one of claims 1 to 7, wherein a ratio (Wt / Wb) between the bead width Wb and the width Wt from the center of the core to the bead toe is 0.45 or more and 0.55 or less.

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