JPH1035230A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify and facilitate production work of a pneumatic tire by providing the first rubber chafer which extends from the axial inside of bead core to the axial outside and made of a particular rubber compound, and the second rubber chafer which extends along the outside of the axial outside part of the first rubber chafer. SOLUTION: A rubber chafer 40 which extends from the axial inside of a bead core 26 to the axial outside is arranged on the outside of a bead reinforcing layer 35 and the radial outside end 41a of the axial inside part 41 of this rubber chafer 40 is positioned on the radial outside from a point separated by 10mm from a bead toe 45 to the radial outside. And also a rubber chafer 47 is arranged outside the axially outside part 42 of the rubber chafer 40 and this rubber chafer 47 is extended to be positioned over the radial outer end 42a from a bead heel 46. And 2.5 to 5.5 weight part of sulfur is compounded to natural rubber as a rubber chafer 40 and also organic metallic cobalt salt is compounded by 0.02 to 0.25weight% in form of metallic cobalt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire using a rubber composition having a specific composition for a rubber chafer.

[0002]

2. Description of the Related Art As a conventional pneumatic tire, for example, as shown in FIG. 3, a pair of bead cores 11 extend from one bead core 11 to the other bead core 11, and
A toroidal carcass layer 13 having a folded portion 12 folded around the bead core 11 at both ends and a number of steel cords embedded therein, and the outside of the carcass layer 13 as the carcass layer 13 A pair of bead reinforcing layers (generally called wire chafers) 14 extending from the inside in the axial direction to the outside in the axial direction of the bead core 11 and having a steel cord embedded therein;
The outer rubber chafer extends from the radially inner side of the bead core 11 to the axially inner side of the bead core 11 along the bead reinforcing layer 14 and extends throughout the bead toe portion 15, and is formed of rubber having excellent anti-destructive properties. 16 and the folded portion 12 and the outside of the bead reinforcing layer 14 extend along the outside from the radial inside of the bead core 11 to the outside of the bead core 11 in the axial direction, and are formed of rubber having excellent wear resistance, and the outer surface thereof. A part of the outer rubber chafer 18 that contacts the rim flange 17, and is disposed radially outward from the inner rubber chafer 16, and covers the radially outer end of the axially inner portion 14a of the bead reinforcing layer 14, An inner auxiliary rubber layer 19 made of rubber having good adhesion to a steel cord, and the outer rubber chafer 18 and the folded portion 12,
It is disposed between the bead reinforcing layer 14 and covers both the folded portion 12 and the radially outer end of the axially outer portion 14b of the bead reinforcing layer 14 and is made of rubber having good adhesion to a steel cord. An outer auxiliary rubber layer 20 is known.

Here, as described above, the four types of rubber layers of the inner and outer rubber chafers 16 and 18 and the inner and outer auxiliary rubber layers 19 and 20 are arranged around the bead core 11 because of these rubber layers. Since different performances are required for the rubber at the position where the layer is disposed, that is, at the position where the inner rubber chafer 16 is disposed (the bead toe portion 1).
In 5), it is necessary to suppress chipping of the bead toe, so that it has anti-destructive properties. In the position where the outer rubber chafer 18 is arranged, it is necessary to suppress wear due to friction with the rim flange 17, so that wear resistance is further increased. At the positions where the inner and outer auxiliary rubber layers 19 and 20 are disposed,
12, since it is necessary to suppress the separation generated based on the cut end of the steel cord exposed at the radially outer end of the bead reinforcing layer 14, since adhesiveness to the steel cord is required, Outer rubber chafers 16 and 18 and inner and outer auxiliary rubber layers 19 and 20 are rubbers satisfying the above requirements, that is, inner rubber chafers 16.
Rubber with excellent anti-destructive properties, rubber with excellent wear resistance on the outer rubber chafer 18, and rubber with good adhesion to steel cords on the inner and outer auxiliary rubber layers 19 and 20 Because it is.

[0004]

When the rubber having the required performance is arranged at each position as described above,
The rubber placement work is troublesome (specifically, the number of times the rubber layer is applied increases) and the work efficiency is reduced. However, there is a rubber having a plurality of required performances at a plurality of positions. If this is the case, the number of times of applying the rubber layer can be reduced. For this reason, conventionally, a rubber excellent in a plurality of performances, for example, both excellent in anti-breaking property and adhesiveness to a steel cord, has been desired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire whose manufacturing operation is simple and easy by using a rubber composition excellent in both anti-destructive property and adhesion to steel cord for a rubber chafer. I do.

[0006]

SUMMARY OF THE INVENTION The purpose of the invention is as follows.
A toroidal carcass layer having a pair of bead cores, extending from one bead core to the other bead core, having a folded portion at both ends folded around the bead core, and having a number of steel cords embedded therein. The outer side of the carcass layer extends along the carcass layer from the axially inner side of the bead core to the axially outer side, and the radially outer end of the axially inner portion is 10 mm radially outward from the bead toe.
At a point radially outward from the point P
The radially outer end of the axially outer portion is located radially outward from the radially outer end of the folded portion, and the boundary provided between the axially inner portion and the axially outer portion is the entire bead toe portion. A first rubber chafer extending from the outer surface of the first rubber chafer and extending along the first rubber chafer along the first rubber chafer and having excellent wear resistance; And a second rubber chafer in which a part of the rubber contacts the rim flange. As the first rubber chafer, only 2.5 to 5.5 parts by weight of sulfur is blended with natural rubber, and the organometallic cobalt salt is in the form of metallic cobalt. The pneumatic tire using the rubber composition constituted by mixing only 0.02 to 0.25% by weight with
A toroidal carcass layer having a pair of bead cores, extending from one bead core to the other bead core, having a folded portion at both ends folded around the bead core, and having a number of steel cords embedded therein. Along the outside of the carcass layer along the carcass layer from the axial inside of the bead core to the axial outside,
A pair of bead reinforcing layers in which a steel cord is embedded, and extending outside the bead reinforcing layer from the axially inner side of the bead core to the axially outer side along the bead reinforcing layer, and a radially outer end of the axially inner portion Is located radially outward from the radially outer end of the axially inner portion of the bead reinforcing layer, and the radially outer end of the axially outer portion is more radial than either the bead reinforcing layer and the radially outer end of the folded portion. A boundary portion provided between the axially inner portion and the axially outer portion and extending in the entire bead toe portion.
A rubber chafer, a rubber chafer extending outside the axially outer portion of the first rubber chafer along the first rubber chafer and having excellent wear resistance; And a second rubber chafer contacting the natural rubber, wherein the first rubber chafer is composed of natural rubber containing only 2.5 to 5.5 parts by weight of sulfur, and an organometallic cobalt salt in the form of metallic cobalt of 0.02 to 0.25% by weight. This can be achieved by a pneumatic tire using a rubber composition constituted only by compounding the rubber composition.

In a known pneumatic tire having no bead reinforcing layer (called a wire chafer or the like), only the inner, outer rubber chafer and outer auxiliary rubber layer are arranged around a bead core. However, in the pneumatic tire according to claim 1, the inner rubber chafer and the outer auxiliary rubber layer are integrated to form a first rubber chafer, As a result, the number of times of applying the rubber layer at the time of manufacturing the pneumatic tire is reduced by one, thereby making the tire manufacturing operation simple and easy. Here, the rubber used in the first rubber chafer is a natural rubber in which sulfur and an organometallic cobalt salt are compounded. However, since the natural rubber has elongation crystallinity, it can be used as a synthetic rubber such as polybutadiene rubber. In comparison, the composition is superior in anti-destructive property, and ZnS that contributes to adhesion is easily formed by the addition of sulfur, and the formation of an adhesion layer is promoted by the addition of an organometallic cobalt salt. For this reason, the rubber constituting the first rubber chafer has excellent adhesiveness and anti-destructive property to the steel cord, and as a result, the axially outer portion covering the radially outer end of the folded portion has the folded portion. The separation is effectively suppressed by firmly adhering to the cut end of the steel cord exposed at the radially outer end of the bead, and the boundary extending over the entire bead toe is easily deformed when the rim is removed. Thus, chipping of the bead can be effectively suppressed.

In the pneumatic tire according to the second aspect, the inner rubber chafer and the inner and outer auxiliary rubber layers described in the prior art are integrated into a first rubber chafer, whereby the pneumatic tire is formed. Reduces the number of times the rubber layer is applied during tire production twice to simplify tire production.
Easy going. Since the rubber used in the first rubber chafer is also a natural rubber containing sulfur and an organometallic cobalt salt, the radial outer end of the folded portion and the radial outer end of the bead reinforcing layer in the radial direction are formed. The axially outer portion that covers both outer ends is securely bonded to the cut end of the steel cord exposed at any radially outer end, effectively suppressing separation, and the shaft of the bead reinforcing layer. The axially inner portion covering the radially outer end of the radially inner portion is securely bonded to the cut end of the steel cord exposed at the radially outer end to effectively suppress separation, and further, to the entire bead toe portion. The widened boundary portion can be easily deformed when the rim is attached or detached, and chipping of the bead can be effectively suppressed.

Further, the amount of the organometallic cobalt salt described in claims 3 and 4 can be blended into the coating rubber of the carcass layer and the bead reinforcing layer. When blended, the adhesion between the steel cord of the carcass layer and the bead reinforcing layer and the coating rubber can be improved without lowering the durability. Further, according to the structure described in claim 5, it is possible to prevent a situation in which the first rubber chafer is exposed and comes into contact with the rim flange when the vehicle travels for a long time.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 25 denotes a pneumatic radial tire. The tire 25 has a pair of bead cores 26 and a toroidal carcass layer 27 extending from one bead core 26 to the other bead core 26. Is composed of at least one carcass ply, here one carcass ply. The carcass layer 27 has a main body portion 29 located between the two bead cores 26 in the center in the width direction, and is folded around the bead core 26 at both ends in the width direction, so that the carcass layer 27 extends radially outward along the main body portion 29. It has a folded portion 30 that extends. A large number of steel cords extending perpendicularly to the equatorial plane of the tire (in the radial direction) are buried in the carcass layer 27, and the cut ends of these steel cords are exposed at the radially outer ends 30a of the folded portions 30. doing. 31 is a pair of stiffeners arranged axially outside the main body 29 in a state of being in close contact with it,
The radially inner portions of the stiffeners 31 are arranged between the main body 29 and the folded portion 30. Outside the carcass layer 27 in the bead portion 34, a bead reinforcing layer 35 extending from the inside of the bead core 26 in the axial direction to the outside in the axial direction is arranged along the carcass layer 27, and the bead reinforcing layer 35 has an elastic modulus therein. A steel cord of 2500 kg / mm ² or more is buried in a state inclined to the tire equatorial plane, and is generally called a wire chafer. As a result, the cut ends of these steel cords are
Of the 35, a radially outer end 36a of an axially inner portion 36 located axially inside the bead core 26 and a radially outer end 37a of an axially outer portion 37 located axially outward are exposed. In this embodiment, the radially outer end 37a of the axially outer portion 37 of the bead reinforcing layer 35 is located slightly radially inward from the radially outer end 30a of the folded portion 30. Further, a belt layer and a tread (not shown) are arranged outside the carcass layer 27 in the radial direction, as is well known.

Outside the bead reinforcing layer 35, there are arranged first rubber chafers 40 extending from the inside in the axial direction to the outside in the axial direction of the bead core 26 along the bead reinforcing layer 35, and these first rubber chafers 40 are provided. Is an axially inner portion 41 located axially inward of the bead core 26, an axially outer portion 42 located axially outward of the bead core 26, and a bead core 26.
Radially inward of the axially inner portion
It comprises a boundary portion 43 provided between 41 and an axially outer portion. And these first rubber chafers
The radially outer end 41a of the axially inner portion 41 is located radially outward from the radially outer end 36a of the axially inner portion 36 of the bead reinforcing layer 35. As a result, the radius of the bead reinforcing layer 35 is reduced. The cut end of the steel cord exposed at the radially outer end 36a, in other words, at the radially outer end 36a, is covered by the axially inner portion 41 of the first rubber chafer 40. The radially outer end 42a of the axially outer portion 42 of the first rubber chafer 40 is connected to the axially outer portion 42 of the bead reinforcing layer 35.
37 is located radially outward from both the radial outer end 37a and the radial outer end 30a of the folded portion 30,
As a result, the radially outer end 37a of the bead reinforcing layer 35, in other words, the cut end of the steel cord exposed at the radially outer end 37a, and the radially outer end 30a of the folded portion 30, ie, the radius The cut end of the steel cord exposed at the outer end 30a of the first rubber chafer is the outer end of the first rubber chafer 40 in the axial direction.
Would be covered by 42. Further, the boundary portion 43 of the first rubber chafer 40 extends to the entire bead toe portion 44, that is, to the bead toe 45. As described above, the first rubber chafer 40 has substantially the same shape as that obtained by integrating the inner rubber chafer and the inner and outer auxiliary rubber layers described in the prior art, and as a result, the pneumatic tire 25 At the time of manufacturing, the number of times the rubber layer is attached can be reduced twice, and the tire manufacturing operation can be made simple and easy.

The first rubber chafer 40 is made of natural rubber, which has excellent elongation crystallinity and excellent anti-destructive property as a polymer, as compared with synthetic rubber such as polybutadiene rubber. Sulfur and cobalt naphthenate to improve adhesion to
It contains an organic metal cobalt salt such as cobalt versatate, cobalt stearate, and cobalt borobasate. As described above, the rubber used for the first rubber chafer 40 is a rubber excellent in both the anti-destructive property and the adhesiveness to the steel cord. As a result, as described above, the axially outer portion of the first rubber chafer 40 covering both the radially outer end 30a of the folded portion 30 and the radially outer end 37a of the axially outer portion 37 of the bead reinforcing layer 35. 42 securely adheres to the cut ends of the steel cords exposed at any of the radially outer ends 30a and 37a, thereby effectively suppressing the generation of cracks due to strain during rotation and effectively separating. It suppresses. On the other hand, the axial inner portion 36 of the bead reinforcing layer 35
Rubber chafer covering the radial outer end 36a of the
The axially inner portion 41 of the 40 is securely bonded to the cut end of the steel cord exposed at the radially outer end 36a, and effectively suppresses the separation as described above. Furthermore, the boundary portion 43 of the first rubber chafer 40 extending over the entire bead toe portion 44 can be easily deformed when the tire 25 is attached to or detached from the rim, thereby effectively preventing the bead toe chipping due to the deterioration. It is suppressed.

The reason why the addition of sulfur as described above improves the adhesiveness to the steel cord is that ZnS which contributes to the adhesiveness is easily formed. The reason why the adhesiveness to the cord is improved is that the formation of the adhesive layer can be promoted. And, the sulfur needs to be blended in the range of 2.5 to 5.5 parts by weight. The reason is that if the amount of sulfur is less than 2.5 parts by weight, good adhesion to steel cord cannot be secured, while if it exceeds 5.5 parts by weight, the anti-destructive property of rubber decreases. Because it will. The sulfur is 3.0
It is preferable to mix within the range of 4.5 parts by weight. Also,
The organometallic cobalt salt must be incorporated in the form of metallic cobalt in the range of 0.02 to 0.25% by weight. The reason is that if the amount of the organometallic cobalt salt is less than 0.02% by weight in the form of metallic cobalt, good adhesion to the steel cord cannot be secured, while if it exceeds 0.25% by weight, This is because the effect of improving the adhesiveness is saturated, resulting in a significant disadvantage that the cost increases. It is also conceivable that the rubber used for the first rubber chafer 40 contains (blends) a polyisoprene rubber in order to improve the kneading workability without significantly lowering the adhesiveness and the anti-destructive property. In such a case, the content is preferably in the range of 2 to 30 parts by weight. However, synthetic rubber other than the polyisoprene rubber,
If contained, the adhesion and anti-destructive properties will be significantly reduced,
Inclusion should be avoided. Further, from the viewpoint of improving the anti-destructive property, a polyethylene resin having a melting point of 120 ° C. or more and a melt float rate of 20 g / 10 min or less may be blended in the rubber in an amount of 2 to 20 parts by weight. . In addition, carbon having an N ₂ SA value (one of the indices for measuring the surface area of carbon) of 74 to 100 m ² / g is used as the rubber.
To 70 parts by weight.

Here, in order to improve the adhesion between the coating rubber of the carcass layer 27 and the bead reinforcing layer 35 in contact with the first rubber chafer 40 and the steel cord embedded therein, Similarly, an organometallic cobalt salt can be blended. In this case, the compounding amount is preferably in the range of 1 to 2 times the amount of the organic metal cobalt salt compounded in the first rubber chafer 40. The reason is that the amount of sulfur contained in the coating rubber of the carcass layer 27 and the bead reinforcing layer 35 is smaller than the amount of sulfur contained in the first rubber chafer 40. The effect must be compensated for by the organometallic cobalt salt, and as a result, the compounding amount is preferably at least one time as described above. On the other hand, if the compounding amount is 2
If it exceeds twice, the durability of the rubber will decrease, so that it is preferably at most twice.

Reference numeral 47 denotes a second rubber chafer disposed outside the axially outer portion 42 of the first rubber chafer 40. The second rubber chafer 47 extends along the first rubber chafer 40. Radial outer edge 42 from bead heel 46
a. Since the second rubber chafer 47 is in contact with the rim flange 48 at a part of the outer surface, here the inner part in the radial direction, the second rubber chafer 47 has excellent wear resistance to withstand friction with the rim flange 48 during traveling. It is made of rubber. The thickness t of the second rubber chafer 47 at the portion in contact with the rim flange 48 is preferably 0.70 mm or more. The reason is 0.
If it is less than 70 mm, the second rubber chafer 47 will be worn out and the first rubber chafer 40 will be exposed during a long run, and the first rubber chafer 40 with insufficient abrasion resistance will contact the rim flange 48. This is because there is a risk of doing so. 49 is an inner liner.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the bead reinforcing layer 35 in the first embodiment is omitted. As a result,
The axially inner portion 51 of the first rubber chafer 50 does not have to extend significantly outward in the radial direction, but its radially outer end 51a is located radially outward from a point P which is 10 mm radially outward from the bead toe 45. Must extend to
The reason is that the region where the bead toe chipping occurs when the tire 25 is detached from the rim is the region from the bead toe 45 to the point P. It is necessary to arrange. The radial outer end 51a is a bead toe.
A distance of 50 mm or more radially outward from 45 is not preferable because it increases the cost and increases the weight. Since the axially outer portion 52 of the first rubber chafer 50 only needs to be able to cover the cut end of the steel cord exposed at the radially outer end 30a of the folded portion 30, the radially outer end 52a
Is only required to be located radially outward from the radially outer end 30a of the folded portion 30. Other configurations and operations are the same as those of the first embodiment.

[0017]

Next, test results will be described. In this test, as a conventional example, test examples 1 to 7 and comparative examples 1 to 9, a rubber having a composition shown in Table 1 below and a pneumatic radial using the rubber as a first rubber chafer were used. The tire was prepared. Here, the size of the tire used in the test was 11R22.5 14PR.

[Table 1] In Table 1, polymer A was prepared by blending 30 parts by weight of polyisoprene rubber with natural rubber, polymer B was prepared by mixing 100% of natural rubber, and polymer C was prepared by blending 50 parts by weight of styrene butadiene rubber with natural rubber. For carbon, sulfur, vulcanization accelerator, and polyethylene, the compounding amount is indicated by parts by weight, and for cobalt, cobalt naphthenate is compounded, and the compounding amount is indicated by weight% of metallic cobalt. . In the conventional example, carbon is
In the HAF grade, test and comparative examples, LS-HAF grade is used.

Next, adhesion and breaking elongation tests were performed on the rubbers of the conventional, test and comparative examples described above, and a toe chipping test and an endurance running test were performed on each of the conventional, test and comparative tires. For evaluation of adhesion and crack growth in tires), separation resistance test (adhesion in tires,
(For evaluation of crack growth), and the results are shown in Table 2 below.

[Table 2] Here, in the adhesion test, after five steel cords extending in the longitudinal direction were evenly embedded in a rectangular parallelepiped raw rubber,
In this test, a test piece was prepared by vulcanizing at 145 ° C. for 60 minutes while applying a surface pressure of kg / cm ² for 60 minutes, and then three steel cords were pulled out from the test piece by a tensile tester. The coverage (%) of the rubber adhered to the cord surface thus pulled out is the test result. The elongation at break test is a test in which each rubber was left to age in a gear oven at 100 ° C. for 24 hours and then pulled at 25 ° C. until it broke with a tensile tester. The elongation was measured, and the value was indicated as an index with the value of Test Example 1 taken as 100. Furthermore, in the toe chipping test, after running the tire on a drum at 60 km / h at 70,000 km while applying a normal load to each tire filled with the normal internal pressure, whether toe chipping occurs when the tire is attached / detached with the rim assembly machine This is a test of whether or not the test is performed, and the presence or absence of the test is a test result. In addition, the endurance running test is a test in which each tire filled with the normal internal pressure is run at a speed of 60 km / h on the drum at a speed of 60 km / h until a failure occurs in the bead portion while applying a load of 200% of the normal load. The conventional example 1
The index is displayed as 00. Furthermore, the separation resistance test is a test in which each tire filled with the normal internal pressure is run at a speed of 60 km / h on the drum for 70,000 km while applying a normal load, and separation is generated at the radially outer end of the bead reinforcing layer of each tire. The lengths of these separations were measured at four points on the circumference on the separation side and on the anti-separation side, and the average value of the measurement results was indicated as an index with the conventional example being 100. The above-mentioned normal internal pressure and normal load are based on the air pressure-load capacity correspondence table corresponding to the size of the radial ply tire specified in JATMA YEAR BOOK. As is clear from the above test results, a mixture of natural rubber or a blended rubber of natural rubber and polyisoprene rubber containing 2.5 to 5.5 parts by weight of sulfur and 0.02 to 0.25% by weight of an organometallic cobalt salt in the form of metallic cobalt was used. The test example is generally superior to the conventional example and the comparative example.

[0019]

As described above, according to the present invention, the rubber composition excellent in both the anti-breaking property and the adhesiveness to the steel cord is used for the first rubber chafer, so that the pneumatic tire manufacturing operation can be performed. Became simple and easy.

[Brief description of the drawings]

FIG. 1 is a meridian sectional view near a bead portion showing a first embodiment of the present invention.

FIG. 2 is a meridian sectional view near a bead portion showing a second embodiment of the present invention.

FIG. 3 is a meridian sectional view near a bead portion showing an example of a conventional pneumatic tire.

[Explanation of symbols]

 25 ... pneumatic tire 26 ... bead core 27 ... carcass layer 30 ... folded part 30a ... radial outer end 35 ... bead reinforcing layer 36 ... axial inner part 36a ... radial outer end 37 ... axial outer part 37a ... radial outer End 40 ... First rubber chafer 41 ... Axial inner part 41a ... Radial outer end 42 ... Axial outer part 42a ... Radial outer end 43 ... Boundary part 44 ... Bead toe part 45 ... Bead toe 47 ... Second rubber chafer 48… Rim flange

Claims (5)

[Claims] 1. A toroidal shape having a pair of bead cores, a bent portion extending from one bead core to the other bead core, and folded at both ends around the bead core, and having a number of steel cords embedded therein. A point extending from the inside of the bead core in the axial direction to the outside of the bead core along the carcass layer along the outside of the carcass layer, and the radially outer end of the inner part in the axial direction is separated from the bead toe by 10 mm radially outward. P is located radially outward, and the radially outer end of the axially outer portion is located radially outward from the radially outer end of the folded portion, and between the axially inner portion and the axially outer portion. A first rubber chafer having a boundary portion provided on the entire bead toe portion, and an outer side of an axially outer portion of the first rubber chafer being provided on the first rubber chafer. A second rubber chafer extending along the outer periphery and having abrasion resistance and having a part of an outer surface in contact with a rim flange;
From 2.5 to natural rubber as a rubber chafer
A pneumatic tire characterized by using a rubber composition comprising only 5.5 parts by weight and an organometallic cobalt salt in an amount of 0.02 to 0.25% by weight in the form of metallic cobalt. 2. A toroidal shape having a pair of bead cores, extending from one bead core to the other bead core, and having, at both ends, a folded portion that is folded around the bead core, in which a number of steel cords are embedded. A carcass layer, a pair of bead reinforcing layers having a steel cord embedded therein while extending from the inside of the bead core in the axial direction to the outside of the bead core along the carcass layer along the carcass layer, The outer side extends along the bead reinforcing layer from the axially inner side of the bead core to the axially outer side, and the radially outer end of the axially inner portion is located radially outward from the radially outer end of the axially inner portion of the bead reinforcing layer. And the radially outer end of the axially outer portion is located radially outward of any of the bead reinforcing layer and the radially outer end of the folded portion. A first rubber chafer having a boundary portion provided between the axially inner portion and the axially outer portion extending over the entire bead toe portion; A second rubber chafer extending along the rubber chafer and having excellent abrasion resistance and having a part of an outer surface in contact with a rim flange; Only 2.5 to 5.5 parts by weight of sulfur is added to the rubber, and the organometallic cobalt salt is added in the form of metallic cobalt.
A pneumatic tire using a rubber composition constituted by compounding only 0.02 to 0.25% by weight. 3. An organometallic cobalt salt is compounded in the coating rubber of the carcass layer, and the compounding amount is adjusted to a first amount.
The pneumatic tire according to claim 1 or 2, wherein the amount is in the range of 1 to 2 times the compounding amount in the rubber chafer. 4. The method according to claim 2, wherein an organometallic cobalt salt is compounded in the coating rubber of the bead reinforcing layer, and the compounding amount is within a range of 1 to 2 times the compounding amount in the first rubber chafer. Pneumatic tires. 5. The pneumatic tire according to claim 1, wherein a thickness t of the second rubber chafer at a portion in contact with the rim flange is 0.50 mm or more.