JP2000198326A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bead excellent in durability. SOLUTION: The pneumatic tire is provided with a folded back part 6b integrally provided to a body part 6a stretched from a tread part via a sidewall part to a bead core 5 of a toe of bead and folded back outward at the bead core 5, a carcass including a carcass ply wherein a carcass cord is obliquely arranged at an angle of 70 to 90 degrees in regard to a tire equator, and a bead apex rubber 8 taperingly extended outward from the bead core 5 in a tire radial direction. The folded back part 6b extends along an outside surface 8o in a tire axial direction of the bead apex rubber 8 and includes a proximity part X wherein a distance (t) between cords of the folded back part 6b and the body part 6a is a minimum value tmin. The minimum value tmin is 0.15 to 7.0 times of a diameter D of the carcass cord. A gradually increasing area Y wherein the distance (t) between cords of the folded back part 6b and the body part 6a of the carcass ply gradually increases outward in the tire radial direction, is formed outside of the proximity part X in the tire radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic tire capable of improving the durability of a bead portion.

[0002]

2. Description of the Related Art The present applicant has already proposed Japanese Patent No. 2724291 as a pneumatic tire capable of improving the durability of a bead portion. In this proposal, as shown in FIG. 12, a slim bead portion is obtained by shaving the inner surface of the bead portion from a conventional shape shown by a chain line. Also, the profile shape of the carcass is changed in accordance with this. For example, the carcass ply body d2 extending between the bead cores c and c (only one is illustrated in FIG. 12) has a substantially radially inner end side in the tire radial direction, and the carcass ply turnback d1 has Immediately after being turned around the bead core c, the main body d closes to the main body d2 of the carcass ply.
2 to form a parallel portion g extending substantially in parallel.

In such a carcass profile, the folded portion d1, which is apt to be damaged, approaches the neutral line (neutral axis) side of deformation, so that the compressive force on the folded portion d1 is greatly reduced, and the bead is formed. It is possible to prevent distortion from being concentrated at a specific position of the part. As a result, with such a bead structure, the rubber thickness of the bead portion can be reduced (the bead portion can be made slim), and the heat generation can be significantly reduced and the durability can be improved.

The present inventors have investigated the damage process of such a bead structure in order to further improve the durability of the bead portion. As a result, since the outer end e of the folded portion d1 tends to approach the tire maximum width position where bending is severe,
It has been found that stress tends to concentrate, and such stress concentration causes "initial cracking", which is a small crack of rubber, near the outer end e of the folded portion d1. Then, it was found that such initial cracks were affected by the repeated deformation of the tire and proceeded between the main body portion d2 and the folded portion d1 toward the bead apex rubber b, leading to major damage such as separation.

In order to prevent the initial cracking, it is conceivable to increase the thickness of rubber (hereinafter, sometimes simply referred to as "inter-ply rubber") between the main body portion d2 and the folded portion d1. However, when the thickness of the inter-ply rubber is uniformly increased from the outer end of the bead apex rubber b to the outer end e of the folded portion d1, the bead apex rubber in which the deformation during running becomes relatively large even in the folded portion d1. In the vicinity of the outer end of b, a large shearing force or heat is applied to the rubber between the plies, and conversely, there is a possibility that an initial crack may occur at the outer end of the bead apex rubber b.

In the case of a tube-type pneumatic tire, the flange height of the rim is generally large, so that a large amount of frictional heat is generated during running because the surface of the bead portion and the rim flange rub widely. Due to the repetition of such heat generation, in the tube type tire, the rubber at the bead portion is hardened or deteriorated, causing cracks on the surface, and the cracks progress inside the tire in proportion to the running distance and turn back. It is also known that damage called "chaffing", which leads to separation of the part d1, is likely to occur. In addition, when the rim is assembled or removed from the tire, the bead portion may be damaged by the rim assembly lever or the like, and the carcass cord may be corroded or broken due to the damage.

In order to prevent these inconveniences, it is conceivable that a bead portion is reinforced by arranging a cord reinforcing layer outside the folded portion d1 in the tire axial direction. However, even if the conventional cord reinforcing layer is directly applied to the above-described bead structure, a substantially effective effect may not be obtained. That is, in the bead structure as shown in FIG.
The carcass profile is formed by approximating the profile at the time of pneumatic filling, and the folded portion d1 is brought close to the main body portion d2, and the stress acting on the outer end e of the folded portion d1 due to deformation of the tire due to internal pressure filling or running is reduced. Minimized. For this reason, most of the internal stress due to the tire deformation is held by the rubber portion disposed outside the carcass in the tire axial direction. Therefore, for example, when the arrangement position of the cord reinforcing layer is related to the rubber portion, the cord reinforcing layer may receive a large stress and may become a starting point of structural damage.

The present invention has been devised in view of the above-mentioned situation. First, for example, in the first invention, for example, near the outer end of a bead apex rubber, a portion between a folded portion of a carcass ply and a cord of a main body portion is provided. While providing the proximity portion where the distance is minimized, forming a gradually increasing region in which the distance between the cords of the main body portion and the folded portion gradually increases outward in the tire radial direction, outside the proximity portion in the tire radial direction. Basically, for the purpose of providing a pneumatic tire that can improve durability by suppressing initial cracking which becomes a starting point of separation at the outer end of the folded portion, and the outer end of the bead apex rubber, and in particular, to provide a radial tire for heavy load. I have.

According to the second aspect of the present invention, the bead portion of the carcass structure having the proximity portion where the distance between the folded portion of the carcass ply and the cord of the main body is minimized is reinforced by the cord reinforcing layer, and the cord is reinforced. Regarding forming a second gradually increasing region in which the cord-to-cord distance between the layer and the carcass gradually increases toward the outer side of the tire radius, and the third invention,
Pneumatic tires that can improve the durability of the bead part by increasing the trauma resistance and suppressing the separation of the cord reinforcement layer, especially by regulating the positions of both ends of the cord reinforcement layer optimally, especially It aims to provide radial tires for heavy loads.

[0010]

According to the first aspect of the present invention, the bead core is folded back from the inner side to the outer side in the tire axial direction by the bead core to a main body from the tread portion to the side wall portion to the bead core of the bead portion. The folded part is provided integrally, and the carcass cord is 70 to 9 with respect to the tire equator.
A pneumatic tire having a carcass having a carcass ply arranged at an angle of 0 °, wherein the bead portion includes a bead apex rubber tapering and extending radially outward from a bead core in a tire radial direction. The bead apex rubber extends radially outward along the outer surface of the bead apex rubber in the tire axial direction, and the inter-cord distance (t), which is the distance between the carcass cord of the folded portion and the carcass cord of the main body, is increased. The carcass cord has an adjacent portion having a minimum value (tmin), and the minimum value (tmin) is 0.15 to 7.0 times the diameter D of the carcass cord. , Characterized in that the cord-to-cord distance (t) gradually increases outward in the tire radial direction.

In the invention according to a second aspect, the bead portion has a height (h) from the bead base line to the folded portion.
0) at least a part of the range of 0.4 times or more and 1.0 times or less includes the above-mentioned increasing region, and an arbitrary height (h) of the increasing region from the bead base line; Ratio (t) to the inter-code distance (t) at the time (h).
h) is substantially constant and the value is 0.01 to 0.07
The pneumatic tire according to claim 1, wherein .

According to a third aspect of the present invention, the bead portion is at least partly in a range of 1.1 to 1.5 times the height (ha) of the bead apex rubber from the bead base line. In addition to the proximity portion, the proximity portion has a continuous minimum value (tmin) of the inter-code distance (t).
The pneumatic tire according to claim 1 or 2, wherein a carcass cord of the main body portion and the folded portion forms a parallel region that extends substantially in parallel.

According to a fourth aspect of the present invention, the folded portion has an inner portion in which at least the ply portion forming the gradually increasing region is disposed inside the ply portion in the tire axial direction.
The ply portion is covered with an insulation rubber different from a sidewall rubber having an outer portion disposed outside in the tire axial direction, and the insulation rubber is composed of one or two rubber compositions. The pneumatic tire according to any one of claims 1 to 3, wherein:

According to a fifth aspect of the present invention, in the insulation rubber, the inner portion and the outer portion are integrated at an outer end of the folded portion, and the tire is radially outside the outer end of the folded portion. The pneumatic tire according to claim 4, further comprising a tapered portion extending and terminating in a tapered shape.

According to a sixth aspect of the present invention, there is provided a vehicle body wherein a bend core is integrally provided on a main body portion extending from a tread portion to a sidewall portion to a bead core of a bead portion so as to be folded back from inside to outside in the tire axial direction by the bead core. A pneumatic tire provided with a carcass having a carcass ply in which cords are arranged at an angle of 70 to 90 degrees with respect to the tire equator, wherein the bead portion extends from a bead core in a radially outward direction in a tire. An apex rubber, the folded portion extends radially outward along the tire axial direction outer surface of the bead apex rubber, and a distance between a carcass cord of the folded portion and a carcass cord of the main body. Has a proximity where the inter-code distance (t) is a minimum value (tmin), and this minimum value (tmin) is While the diameter of the carcass cord is set to 0.15 to 7.0 times the diameter D, the bead portion includes a cord reinforcing layer extending inward and outward in the tire radial direction on the outer side in the tire axial direction of the turn-back portion. , The outer end of which is the height of the folded portion from the bead base line (h0)
While the inner end extends at least up to the maximum width of the cross-section of the bead core, and the cord reinforcing layer extends from the bead base line to the cord reinforcing layer. In a region of 50% or more and 100% or less of the height F in the tire radial direction up to the outer end of the tire, the inter-cord distance, which is the distance between the carcass cord of the folded portion and the reinforcing cord of the cord reinforcing layer, is A second gradually increasing region that gradually increases radially outward, the second increasing region including a tire radial height f from the bead baseline and the cord at the height f. The ratio (j / f) to the distance (j) is 0.01 to
0.13.

According to a seventh aspect of the present invention, there is provided a car body which is provided integrally with a folded portion which is turned from the inside to the outside in the tire axial direction by the bead core in a body portion extending from the tread portion to the side wall portion to the bead core of the bead portion. A pneumatic tire provided with a carcass having a carcass ply in which cords are arranged at an angle of 70 to 90 degrees with respect to the tire equator, wherein the bead portion extends from a bead core in a radially outward direction in a tire. An apex rubber, the folded portion extends radially outward along the tire axial direction outer surface of the bead apex rubber, and a distance between a carcass cord of the folded portion and a carcass cord of the main body. Has a proximity where the inter-code distance (t) is a minimum value (tmin), and this minimum value (tmin) is While the diameter D of the carcass cord is set to 0.15 to 7.0 times, a cord reinforcement layer provided outside the carcass ply is provided in the bead portion, and the cord reinforcement layer is a tire of the folded portion. An outer portion extending outward in the tire radial direction along the outer side in the axial direction, and a winding portion connected to the inner end side of the outer portion in the tire radial direction and extending along the tire radially inner side of the bead core, and The outer end in the tire radial direction is the innermost point (C) of the bead core in the tire radial direction.
i) in a radial region between a radially outermost point (Co) of the bead core and a position spaced outwardly in the tire radial direction by a distance equal to the maximum cross-sectional width (BW) of the bead core from the outermost point (Co). A straight line (K) drawn from the center of gravity (Z) of the cross section of the bead core to the inside of the bead core perpendicular to the direction of the maximum width of the cross section of the bead core; It is arranged in a region sandwiched by an axial line (N) extending inward in the axial direction.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the first invention of the present invention will be described below with reference to the drawings. FIG. 1 illustrates, as a pneumatic tire, a tubeless type heavy duty radial tire 1 (hereinafter, may be simply referred to as “tire 1”) used for trucks, buses, and the like. FIG.
1 shows a meridional section (right half) in a normal state where the tire 1 is mounted on a normal rim J (15 ° taper deep bottom rim) and filled with a normal internal pressure and no load is applied.

In the present specification, the "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. For example, a standard rim for JATMA and a rim for TRA "Design Rim" or "Measuring Rim" for ETRTO. The "normal internal pressure" is the air pressure specified for each tire in the standard system including the standard on which the tire is based. The maximum air pressure for JATMA, and the table "TIRE LOAD LIMITS" for TRA. AT VARIOUS COLD INFLATI
ON PRESSURES "maximum value, ETRTO"
INFLATION PRESSURE ", but if the tire is for a passenger car, the pressure is 180 kPa.

In FIG. 1, a tire 1 has a tread 2
A pair of sidewall portions 3 extending inward in the tire radial direction from both ends thereof, and a bead portion 4 located at an inner end of each sidewall portion 3 and seated on the regular rim J.
And In addition, the tire 1 has a body portion 6a extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3 and integrally provided with a turn-back portion 6b that is folded back from the inside to the outside in the tire axial direction by the bead core 5. The carcass 6 includes at least one carcass ply 6A.

The carcass ply 6A is formed by AA in FIG.
As shown in FIG. 4 which is a cross section, in this example, the carcass cord 6
6g of topping rubber on both sides of the code array where c is arranged
And the carcass cord 6
c is inclined so as to have an angle range of 70 to 90 ° with respect to the tire equator C. As the topping rubber 6g, for example, a 100% modulus is 37 to 47 kgf /
cm ² (3628-4610 kPa) is preferred.
In this example, a steel cord is used as the carcass cord 6c, but an organic fiber cord such as nylon, rayon, polyester, or aromatic polyamide may be used as necessary and according to the category of the tire. The carcass 6 of the present embodiment is exemplified by a carcass ply 6A formed by inclining a steel cord at an angle of about 90 ° with respect to the tire equator C.

A belt layer 7 is disposed radially outside the carcass 6 and inside the tread portion 2. Belt layer 7
In this example, the steel cord is attached to the tire equator C,
For example, an innermost belt ply 7A inclined at an angle of about 60 ± 10 ° and a belt ply 7B in which a steel cord is inclined at a small angle of 30 ° or less with respect to the tire equator C,
7C and 7D are overlapped, for example, by providing one or more places where the belt cords cross each other between plies.
2 illustrates a layer structure. The belt layer 7 may be made of another cord material such as rayon, nylon, aromatic polyamide, nylon, or the like, if necessary.

The bead portion 4 includes the main body portion 6a.
A bead apex rubber 8 having a substantially triangular cross section is tapered from the bead core 5 to the outside in the tire radial direction. The height of the bead apex rubber 8, that is, the height ha from the bead base line BL to the outer end 8 t of the bead apex rubber 8 is 6 to 31 of the tire section height H (shown in FIG. 1).
%, More preferably 8 to 22%, more preferably 8 to 1%.
Preferably, the height is set to 4%, and in this example, the height is set to about 11%. The bead base line BL is a tire axial direction line passing through a rim diameter defined by the standard or the like, and the tire section height H is the outermost position in the tire radial direction from the bead base line BL in the standard state. Up to the height.

As shown in FIG. 2, the bead apex rubber 8 has an inner surface 8 in the tire axial direction in this embodiment.
i is formed in a substantially linear shape inclined substantially parallel to the main body 6a, and is formed in an arc shape in which the outer surface 8o in the tire axial direction is depressed inward in the tire axial direction. The bead apex rubber 8 has a JISA hardness of 60, for example.
~ 99 °, 100% modulus is 14 ~ 120kgf / cm ²
(1372 to 11768 kPa).

In the present embodiment, the bead core 5 is formed to have a substantially hexagonal cross section by spirally winding a steel wire 5w a predetermined number of times, and the outer peripheral portion is covered with, for example, wrapping rubber. Also, bead core 5
Is configured such that the inner piece 5i, which is one side on the inner side in the tire radial direction, is about 15 ° with respect to the tire axial direction, that is, along the inclination of the rim seat surface J1 (shown in FIG. 1) of the rim J. The bead core 5 may employ a wire material made of an aromatic polyamide in addition to a steel wire.

The folded portion 6b has an outer end 6t in the radial direction of the tire located radially outward beyond an outer end 8t of the bead apex rubber 8. The outer end 6t
In this example, the end is located radially inward from the maximum width point M, which is the tire maximum width position, and terminated so as to have a height h0 with a relatively small amount of distortion under load. The height of the turn-back portion 6b, that is, the height h0 in the tire radial direction from the bead base line BL to the outer end 6t of the turn-back portion.
Is larger than the height ha of the bead apex rubber and 15 mm from the bead base line BL to the tire section height H.
-50%, more preferably 20-40%, and in this example, about 32% is exemplified.

The folded portion 6b extends radially outward along the outer surface 8o of the bead apex rubber 8. In the present embodiment, the folded portion 6b is located near the outer end 8t of the bead apex rubber 8, and the distance between the folded portion 6b and the carcass cords 6c, 6c of the main body 6a is the inter-cord distance t (measured as shown in FIG. 4). Is the minimum value tmi
n, and the minimum value tmin is set to be 0.15 to 7.0 times the diameter D of the carcass cord 6c.

As described above, by reducing the inter-cord rubber volume by minimizing the inter-cord distance t in the vicinity of the outer end 8t of the bead apex rubber 8, the inter-ply rubber in the vicinity of the outer end 8t of the bead apex rubber 8 is reduced. A large shear force and heat generation can be prevented from acting, and the above-mentioned initial crack can be suppressed. If the minimum value tmin is less than 0.15 times the diameter D of the carcass cord 6c, the cord-to-cord distance between the main body 6a and the turn-back portion 6b becomes extremely small,
There is a tendency that the strength of the rubber against deformation at this portion tends to be insufficient. Conversely, if it exceeds 7.0 times, a large amount of heat is generated due to the shearing force acting on the rubber between the plies of the main body 6a and the folded portion 6b. Is likely to be the starting point for separation. From such a viewpoint, the minimum value tmin of the inter-cord distance of the adjacent portion X is preferably set to be equal to the carcass cord 6c.
0.15 to 5.0 times, more preferably 0.1 times the diameter D of
It is desirable that the ratio be 5 to 4.5 times, more preferably 0.5 to 3.5 times, and still more preferably 0.8 to 2.5 times.

Further, such a proximity portion X is formed at least partially within a range of 1.1 to 1.5 times the height ha of the bead apex rubber 8 from the bead base line BL. Is desirable. The proximity portion X may be formed, for example, locally, but the distance between the cords t
Are formed in the tire radial direction while forming the minimum value tmin, thereby forming a parallel area G (shown in FIG. 2) in which the carcass cords 6c, 6c of the main body portion 6a and the folded portion 6b extend substantially in parallel. Is particularly desirable. At this time,
It is desirable that at least a part, and preferably all, of the parallel region G has a range of 1.1 to 1.5 times the height ha of the bead apex rubber. It goes without saying that the parallel region G may exist beyond this range. In the parallel region G, the ratio (tmin / h) between an arbitrary height h from the bead base line BL and the inter-cord distance at this arbitrary height h (constant at tmin in this example) is 0. .
01 to 0.07, more preferably 0.02 to 0.07.
05 is also preferable. The same units are used for h and t.

As a result of various experiments by the present inventors, when the parallel region G formed by the above-mentioned adjacent portion X is formed, heat generated due to shearing force acting on this portion can be effectively dispersed, and the bead apex rubber 8 It has been found that the durability of the bead portion 4 can be significantly improved because the effect of suppressing the initial cracks generated near the outer end 8t is further improved.

Further, in the present embodiment, as shown in an enlarged view in FIG. 2, the main portion 6a of the carcass ply is provided outside the proximity portion X in the tire radial direction (in this example, following the parallel portion G).
This illustrates an example in which a gradually increasing region Y is formed in which the inter-cord distance t between the first and second folded portions 6b gradually increases toward the outer side in the tire radial direction to the outer end 6t of the folded portion 6b. By providing such a gradual increase region Y, the thickness of the rubber between plies between the outer end 6t of the folded portion 6b and the main body portion 6a can be increased relative to the proximity portion X. 6
Initial cracking at the outer end 6t of b can be suppressed for a long time. On the other hand, the thickness of the rubber between the plies between the main body portion 6a and the folded portion 6b is the outer end 8t of the bead apex rubber 8.
, The thickness of the rubber between the plies near the outer end 8t of the bead apex rubber 8 can be made relatively small, and even in this portion, the initial cracking which becomes the starting point of the separation can be achieved. Can be prevented. That is, in the present embodiment, by providing such a gradually increasing region Y, both the outer end 6t of the folded portion 6b and the outer end 8t of the bead apex rubber 8 are suppressed from initial cracks serving as separation starting points, and the bead portion is formed. 4 can be improved in durability.

In this embodiment, the bead portion 4 extends from the bead base line BL to the outer end 6t of the folded portion in a range of 0.4 to 1.0 times the height h0 from the bead base line BL to the gradually increasing region. The example formed as Y is illustrated. However, the gradually increasing region Y is not limited to this range, and is formed in at least a part of this range, for example, 0.5 times the height h0 of the outer end 6t of the folded portion 6b from the bead base line BL. The range may be not less than 1.0 and not more than 1.0 times, and further may be in the range of 0.8 to 1.0 times.

In the gradual increase area Y of this embodiment, the ratio (t / h) of an arbitrary height h from the bead base line BL to the inter-cord distance t at this arbitrary height h is substantially constant. It shows a gradual increase. As a result, the outer end 6 of the folded portion 6b
The thickness of the inter-ply rubber can be increased in a uniform increment according to the height from the bead base line BL toward the vicinity of t, and a good initial crack preventing effect can be exhibited. At this time, the value of the ratio (t / h) is preferably 0.01 to
0.07, more preferably 0.02 to 0.05, and still more preferably 0.03 to 0.05.

If the ratio (t / h) is less than 0.01, the effect of increasing the thickness of the rubber between plies may not be sufficiently obtained at the position of the outer end 6t of the folded portion 6b. The effect of suppressing the initial cracking at the outer end 6t tends to decrease relatively. Conversely, when the ratio (t / h) is greater than 0.07, the main body 6a and the folded portion 6
The thickness of the rubber interposed between the ply and the ply becomes too large, and this portion generates heat due to shear deformation during running of the tire, which may cause deterioration of the rubber.

Here, as an example of the above-mentioned "gradual increase", as described above, the inter-code distance t increases linearly according to the height from the bead base line BL (t / h is substantially constant).
However, the present invention includes all other modes in which the inter-code distance t gradually increases. For example, when the inter-code distance increases according to the square of the height h from the bead base line BL (for example, t / h). ² = substantially constant). Also,
In the above-described embodiment, the most preferable mode in which the inter-cord distance t gradually increases to the outer end 6t of the folded portion 6b is shown. However, as shown in FIG. An embodiment in which a gradually increasing region Y is formed in an intermediate portion to reach 6t may be included in the aspect of the present invention. The distance between the cords at the outer end 6t of the folded portion 6b is t1.
(Shown in FIG. 3), the inter-cord distance t1 is larger than the inter-cord distance tmin in the adjacent portion X and 0.5 to 9.0 times the diameter D of the carcass cord 6c, preferably 1. 0.0-6.0 times, more preferably 1.5-4.
It is desirable to make it 5 times.

Further, in the present embodiment, as shown in FIG. 3, the folded portion 6b has an inner portion 10a in which at least the ply portion 6b1 forming the gradually increasing region Y is disposed inside the ply portion 6b1 in the tire axial direction. The ply portion 6b
1 illustrates an example in which the outer rubber member is covered with an insulation rubber 10 having an outer portion 10b disposed outside in the tire axial direction. The insulation rubber 10 is made of a rubber material different from the sidewall rubber 11 in this example.

The inner part 10a is connected to the folded part 6b.
Between the bead apex rubber 8 and the main body 6a.
Of the carcass ply extends outward from the outer end 8t in the tire radial direction, and the inner side surface in the tire axial direction is in contact with the main body 6a of the carcass ply. The outer portion 10b is provided with the folded portion 6
In this example, the bead core 5 extends along the outer surface in the tire axial direction of b and reaches the inside of the bead core 5 in the tire radial direction and terminates.

The insulation rubber 1 of the present embodiment
0 indicates that the inner portion 10a and the outer portion 10b are integrated at the outer end 6t of the folded portion 6b, and extend radially outward from the outer end 6t of the folded portion 6b and terminate in a tapered shape. An example having a tapered portion 10c is illustrated. On the outer side of the insulation rubber 10 in the tire axial direction, the sidewall rubber 11 which is rich in flexibility and is exposed on the outer surface at the sidewall portion 3 and the chafer rubber 12 which is connected to the tire radially inner side and is in contact with the rim J And are arranged.

Such an insulation rubber 10 is
Since the outer end 6t of the folded portion 6b is reliably separated from the sidewall rubber 11 having high flexibility, the effect of preventing separation can be further enhanced. Further, the insulation rubber serves to suppress the peeling off of other rubber to be joined by the tapered portion 10c. From such a viewpoint, the height from the outer end 6t of the folded portion of the tapered portion 10c is 60 mm or more,
More preferably, it is desirable to be 75 mm or more.

The insulation rubber 10 is made of a rubber material different from, for example, the bead apex rubber 8, and is preferably made of, for example, one or two rubber compositions. In this example, as shown in FIG. 3, the main body 6 extends between the inner portion 10a and the tapered portion 10c.
A packing rubber part P1 arranged on the side a and a rubber part using a different rubber composition for the other insulation part P2 are illustrated.

Here, 10 of the packing rubber portion P1
The 0% modulus is, for example, 15 to 47 kgf / cm ² (14
70-4610 kPa), one of the insulation units P2
The 00% modulus is 37-47 kgf / cm ² (3628
-4610 kPa), especially the packing rubber part P
Preferably, it is greater than 100% modulus of 1.
Thereby, the local movement of the outer end 6t of the folded portion 6b can be suitably suppressed by the insulation portion P2 having a relatively large modulus of 100%. In addition, the movement in which the insulation part P2 and the folded part 6b are integrated is 10
The packing rubber portion P2 having a relatively small 0% modulus can be suitably absorbed. The 100% modulus of the sidewall rubber 11 is 10 to 2%.
0 kgf / cm ² (980-1961 kPa). Further, for the chafer rubber 12, the 100% modulus is 5%.
It is desirable to use a rubber composition of 5 to 71 kgf / cm ² (5394 to 6963 kPa).

At the outer end 6t of the folded portion 6b, a cut end surface of a carcass cord having poor adhesiveness, in this example, a steel cord which has not been plated, appears. By
The cut end face can be prevented from directly contacting the flexible side wall rubber 11, which helps to prevent breakage of the rubber between plies. In particular, it is desirable that the thickness te of the outer portion 10b of the insulation rubber 10 be 1 mm or more at the outer end 6t of the folded portion 6b.

FIG. 6 illustrates a bead portion (both tubes and rims are not shown) of a tube-loaded type heavy duty tire as another embodiment of the first invention. In this example, the parallel region G is a bead base line BL.
From about 1.0 to the height ha of the bead apex rubber 8
An example is shown which is formed in a 1.6 times wider area. The gradually increasing region Y is formed from the outside in the radial direction of the parallel region G to the outer end 6t of the folded portion 6b. In this example, the range of the gradually increasing region Y is 0.8 to 1.... Which is the height h0 of the folded portion 6b from the bead base line BL.
It is formed in a small range of 0 times. The gradual increase region Y exemplifies a substantially constant region in which the ratio (t / h) is in the range of 0.02 to 0.03.

In such a heavy duty tire with a tube, it is desirable to use a harder rubber for the bead apex rubber 8 than that of the tubeless type. In addition, for example, an insulation rubber 17 having the same physical properties as the topping rubber of the carcass ply 6A can be arranged outside the folded portion 6b of the carcass ply 6A in the tire axial direction. Further, a rubber material such as halogenated butyl rubber which is hardly permeable to air is provided on the inner surface of the tire.

FIG. 7 shows an embodiment of the second invention.
The same portions as those of the first embodiment of the invention shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the above description and the like are used.
The present embodiment exemplifies a tube-type heavy-load tire as shown in FIG. 6 which can suitably suppress chafing which tends to occur. As shown in FIG. 7, the bead portion 4 of the present example has a single cord reinforcing layer 2 extending inward and outward in the tire radial direction on the outer side in the tire axial direction of the folded portion 6b.
0 is provided to reinforce the rigidity of the bead portion 4. In this example, the carcass 6 has the same configuration as that of FIG. 6, that is, a particularly preferable embodiment in which the carcass 6 includes the proximity portion X and the gradually increasing region Y. However, the carcass 6 only needs to include at least the proximity portion X. .

As shown in a partially enlarged view in FIG. 8, the cord reinforcing layer 20 is formed of a ply in which a reinforcing cord 20c made of, for example, steel or organic fiber is covered with a topping rubber 20g. An example is shown that is arranged to be inclined at an angle of 30 to 90 °, more preferably 30 to 60 ° with respect to the tire circumferential direction. As shown in FIG. 7, the cord reinforcing layer 20 has an outer end 21 in the tire radial direction located at a height of 0.15 times or more and 1.0 times or less the height h0 of the folded portion 6b. The inner end 22 of the layer 20 preferably extends at least up to the maximum width line PC of the cross section of the bead core 5.

If the outer end 21 of the cord reinforcing layer 20 is less than 0.15 times the height h0 of the folded portion 6b, the effect of reinforcing the rigidity of the bead portion 4 is reduced, and the effect of suppressing chafing is obtained. Decrease. Conversely, if the outer end 21 exceeds 1.0 times the height h0 of the folded portion 6b, a large stress strain due to the deformation of the side wall portion 3 during running acts on the outer end 21. Damage is more likely to occur. Further, the inner end 22 of the cord reinforcing layer 20 is
If it does not extend to the maximum width line PC of the cross section, there is a tendency that a region where chafing is easily generated cannot be sufficiently reinforced. From this point of view, the outer end 21 of the cord reinforcing layer 20
The height F from the bead base line BL is
0.15 to 0.80 times, more preferably 0.20 to 0.60 times, more preferably 0.25 to 0.5 times the height h0 of b
It is desirable to set it to 0.50 times, and in particular, it is good to be located inside the outer end 8t of the bead apex rubber 8 in the tire radial direction. The maximum width line P of the cross section of the bead core 5
C is a straight line obtained by extending the maximum width portion of the cross section of the bead core 5 in the maximum width direction as shown in FIG.

The cord reinforcing layer 20 is folded back in a region K of 50% or more and 100% or less of the tire radial height F from the bead base line BL to the outer end 21 of the cord reinforcing layer 20. The inter-cord distance j (measured as shown in FIG. 8), which is the distance between the carcass cord 6c of the portion 6b and the reinforcing cord 20c of the cord reinforcing layer 20, gradually increases radially outward in the tire. One that includes at least a part of the two gradually increasing regions 25 is exemplified. Such a second gradually increasing region 25 is formed by gradually increasing the rubber thickness between the cord reinforcing layer 20 and the folded portion 6b toward the radially outer side of the tire, so that the carcass ply 6A and the folded portion have the same thickness. Similarly to the gradually increasing region Y between the cord reinforcing layer 20b and the cord reinforcing layer 20, the initial cracks and cracks between the cord reinforcing layer 20 and the folded portion 6b can be effectively prevented to suppress separation and consequently chafing for a long period of time. Useful. And, for example, a 100% modulus is between 14 and 65 kgf / cm between the folded portion 6b of the second gradually increasing region 25 and the cord reinforcing layer 20.
² (1372-6374 kPa), more preferably 20
~50kgf / cm ² (1961~4903kPa), more preferably 37~47kgf / cm ² (3628~4610k
It is preferable to interpose the insulation rubber 29 of Pa).

In the second gradually increasing region 25,
The ratio (j / j) of the height f in the tire radial direction from the bead base line BL to the distance j between the cords at the height f.
f) is from 0.01 to 0.13, more preferably from 0.01 to 0.13.
0.10, and more preferably 0.02 to 0.09. The ratio (j / f) is 0.01
If it is less than 3, a sufficient rubber thickness cannot be obtained between the cord reinforcing layer 20 and the folded portion 6b, and the initial crack, rubber breakage, and the like are likely to occur near the outer end 21 of the cord reinforcing layer 20, for example. Conversely, when the ratio (j / f) exceeds 0.13, the rubber thickness between the cord reinforcing layer 20 and the folded portion 6b becomes excessive, and the outer end 21 of the cord reinforcing layer 20 has a large compressive strain. Since it is close to the rubber portion on which the grease acts, the effect of preventing chafing is poor.

The second gradually increasing region 25 may be formed in at least a part of the region K. Preferably, the second gradually increasing region 25 is 70% or more of the region K. Are formed as examples. A radially inner portion of the second gradually increasing region 25 of the cord reinforcing layer 20 can form, for example, a second parallel portion 26 which is close to and substantially parallel to the folded portion 6b of the carcass ply. . In this example, the second parallel portion 26 is formed up to the inner end 22, and the distance j between the cords to the folded portion 6b is, for example, the ratio (j / f) of the height f to 0. 01 to 0.08, more preferably 0.1 to 0.08.
It is desirable to set in the range of 02 to 0.07.

The inner end 22 of the cord reinforcing layer 20 is
FIG. 9A shows an example in which the bead core 5 terminates at the outside in the axial direction. However, as shown in FIG. It may be wrapped around and terminated.
Further, as shown in FIG. 2B, the cord reinforcing layer 20 is provided so as to wind the bead core 5 from the outside in the tire axial direction to the inside and extend radially outward along the inside of the main body 6a in the tire axial direction. it can. In this case, the inner end 22 of the cord reinforcing layer 20 is
Is preferably located radially inward of the outer end 8t.

In this embodiment, the cord reinforcing layer 20 is
Although it is a layer, it can be formed in two layers. In this case, the second gradually increasing region 25 and the like are determined by the cord reinforcing layer disposed closest to the folded portion 6b.

FIG. 10 shows an embodiment of a tubeless type heavy duty tire to which the third invention of the present invention is applied. The same parts as those of the first invention shown in FIGS. 1 to 3 are shown. Are denoted by the same reference numerals, and the above description and the like are cited. Also in the present embodiment, the folded portion 6b
Extending radially outward along the outer surface 8o of the bead apex rubber 8 and near the outer end 8t of the bead apex rubber 8, the distance t between the folded portion 6b and the main body 6 is the minimum value tmin. In the vicinity X. In this example, the proximity portion X is the outer end 6 of the folded portion 6b.
An example in which a parallel region G continuous up to t is formed is illustrated. When the parallel region G is continuous from the outer end 8t of the bead apex rubber to the outer end 6t of the folded portion in this way, the length along the parallel region is 0.5 to 5 of the maximum cross-sectional width BW of the bead core 5. 0.0 times, more preferably 1.0 to
It is desirably 4.0 times, more preferably 2.0 to 4.0 times. In addition, the distance tmin between cords in the parallel region G
Can adopt the above-mentioned range. In addition, in the turnback part 6b,
As indicated by the alternate long and short dash line, the gradually increasing region Y of the first invention can be formed.

In the bead portion 4, a single layer of cord reinforcing layer 13 is disposed outside the carcass ply 6A in this embodiment. The cord reinforcing layer 13 is provided in the folded portion 6.
b, an outer portion 14 extending outward in the tire radial direction along the tire axial direction outer side, and a winding portion 15 continuing to the inner side of the outer portion 14 in the tire radial direction and extending inside the bead core in the tire radial direction. Are exemplified.
For example, in the case of the heavy duty tire of the present example, the cord reinforcing layer 13 is preferably a steel cord, but other than this, an organic fiber cord such as an aromatic polyamide or an aliphatic polyamide can be appropriately used. The cord reinforcing layer 13 is also preferably arranged such that the reinforcing cords are inclined at an angle of 30 to 90 °, more preferably 30 to 60 °, with respect to the tire circumferential direction.

The cord reinforcing layer 13 is disposed along the carcass ply 6A.
The inter-cord distance tf between the carcass cord 6c of A (shown in FIG. 4) and the cord of the cord reinforcing layer 13 is, for example, 0.15 to 4.5 of the diameter D of the carcass cord 6c.
Times, more preferably 0.5 to 3.5 times, even more preferably 0.8 to 2.5 times.

If the inter-cord distance tf is less than 0.15 times the diameter D of the carcass cord, the rubber gauge between the cords becomes excessively thin, and the separation between the carcass ply 6A and the cord reinforcing layer 13 is reduced. If the diameter exceeds 4.5 times the diameter D of the carcass cord 6c, on the contrary, the cord reinforcing layer 13 is exposed to the bead seat surface, and air infiltrates from this portion to cause separation of the carcass ply 6A. In addition, the thickness of the chafer rubber 12 on the bead base surface becomes thinner, which causes the bead seat surface to have reduced durability and rim assembly performance. Preferably, the cord reinforcement layer 13 has the insulation rubber 10 interposed between the cord reinforcement layer 13 and the carcass ply 6A.

In the present embodiment, the positions of the outer end 14t of the outer portion 14 of the cord reinforcing layer 13 in the tire radial direction and the end 15t of the winding portion 15 are appropriately regulated as follows. Thereby, the occurrence of separation or the like at each end of the cord reinforcing layer 13 is suitably suppressed. In the cord reinforcing layer 13, first, the outer end 14 t of the outer portion 14 is located at the innermost point Ci of the bead core 5 in the tire radial direction and the outermost point Co of the bead core 5 in the tire radial direction, and It is arranged in a radial area A between a position equal to the width BW and a distance radially outward from the tire. The reason is that when the outer end 14t of the outer portion 14 is located radially inward of the radially innermost point Ci of the bead core 5 in the tire radial direction, the stress acting on the outer end 14t increases, and the carcass ply 6A This is because separation is likely to occur between the two. Conversely, if the outer end 14t of the outer portion 14 exceeds the radial direction area A, stress concentration is likely to occur at the outer end 14t of the outer portion 14, and edge looseness is likely to occur.

The end 15t of the winding portion 15 is formed by a straight line K drawn from the center of gravity Z of the cross section of the bead core 5 to the inside of the bead core 5 perpendicularly to the direction of the maximum width of the cross section of the bead core 5.
It is important to arrange in a region between the outer end 6t of the folded portion 6b and the axial line N extending inward in the tire axial direction. In addition, it may be located on each straight line K, N. The end 15t of this entangled portion is the straight line K
In the case where the carcass ply is located outside in the tire radial direction than the straight line N, the separation tends to occur between the carcass ply and the carcass ply.

The bead portion 4
The bead portion prevents damage to the carcass directly, even if the rim is damaged by the lever or the like when assembling or removing the rim, thereby preventing early corrosion or breakage of the carcass cord. Can be improved in durability. As shown in FIG. 11, the end 15t of the winding portion 15 of the cord reinforcing layer 13 is connected to the outer end 14 of the outer portion 14.
It may be located radially outward of the tire from t.

As described in detail above, in the present invention, the category of the tire is not limited to the above-mentioned example,
It can be used for various categories of tires such as for small trucks and motorcycles. In the second invention, the cord reinforcing layer may be composed of two layers.

[0060]

EXAMPLE A tubeless type heavy duty radial tire having the basic structure shown in FIG. 1 and having a tire size of 11R22.5 (14PR) was prototyped, and a durability test, tire weight measurement, and the like were performed. For the durability test, the test tire was assembled on a rim with a rim size of 8.25 x 22.5,
The internal pressure is filled to 1000 kPa, and the speed is 2
The tire was driven under the conditions of 0 km / H and a load of 9000 kgf. The running time until the appearance of the tire was damaged was measured, and the tire of the conventional structure (conventional example 1) shown in FIG.
It was indicated by an index of 0 (drum durability test 1). The finish is 10,000 km. Regarding the tire weight, the weight per tire was measured, and the value of Conventional Example 1 was 1
It was indicated by an index of 00. A larger value indicates a larger tire weight.

The specifications of the tire are as follows. <Carcass>-Number of plies: 1-Cord: Steel (3 x 0.17 mm + 7 x 0.20)
mm) Diameter D: 0.9mm ・ Number of cords to be driven: 40 / 5cm (at the inside of the bead core) ・ Cord angle: 90 ° (with respect to the equator of the tire) ・ 100% modulus of prepping rubber: 42kg
f / cm ² (4119 kPa) <Belt layer>-Number of plies: 4-Cord: Steel (3 x 0.20 mm + 6 x 0.35)
mm) ・ Number of cords to be driven: 26 / 5cm ・ Cord angle: + 67 °, + 18 °, -18 °, -18
゜ (vs tire equator) <Insulation rubber> 100% modulus: 41 kgf / cm ² (4021 kP
a) The test results are shown in Table 1. Note that the ratio (t /
h) shows that in Examples 3 and 4, it becomes substantially constant in the range of 0.03 to 0.04.

[0062]

[Table 1]

Next, a prototype radial tire for heavy load having a tube size of 10.00R20 (14PR) having the basic structure shown in FIG. 7 was manufactured, and its durability test, chafing resistance performance, tire weight and the like were evaluated. did. In the durability test, the rim size of the test tire was 7.50.
Except for the × 20 rim, the drum durability test 1 was the same as above. In addition, the anti-chaffing performance is as follows: When running 8000 km in the drum endurance test 1, temporarily stop the rotation of the tires, observe the appearance, and check the number of cracks
One tubed type heavy duty tire (conventional example 2) ranked according to the degree of deformation and having no cord reinforcing layer
It was indicated by an index of 00. The higher the value, the better.

The specifications of the tire are as follows. <Carcass>-Number of plies: 1-Cord: Steel (3 x 0.2mm + 7 x 0.23m)
m) Diameter D: 0.9mm ・ Number of cords to be driven: 38 / 5cm (at the inside of the bead core) ・ Cord angle: 90 ° (with respect to the equator of the tire) ・ 100% modulus of prepping rubber: 42kg
f / cm ² (4119 kPa) <Belt layer>-Number of plies: 4-Cord: Steel (3 x 0.20 mm + 6 x 0.35)
mm) ・ Number of cords to be driven: 26 / 5cm ・ Cord angle: + 67 °, + 18 °, -18 °, -18
゜ (Equator to tire) <Cord reinforcement layer>-Cord: Steel (3 x 0.17 mm + 7 x 0.20)
(mm + W × 0.15mm) ・ Number of cords: 28 / 5cm ・ Cord angle: 45 ° (to the tire circumferential direction) The test results are shown in Table 2. In the example 5, the drum endurance test 1 is inferior to the example 6 because the inner end of the cord reinforcing layer is used as a starting point to cause damage. However, since the bending rigidity of the bead portion is increased, a larger load is applied. Is considered to be advantageous when.

[0065]

[Table 2]

Next, a tubeless type heavy duty radial tire having the basic structure shown in FIG. 10 and having a tire size of 11R22.5 (14PR) was prototyped, and in addition to the drum durability test 1, the tire was manufactured before the rim was assembled. After processing the cut wound, put 200 cc of water into the rim, assemble the rim, run on the drum under the same conditions as the above durability test, add 200 cc of water every 100 hours, until the appearance is damaged. A drum durability test 2 for measuring the running time was performed. The result is 10% that of the conventional example 1.
The index is set to 0, and the larger the value, the better. Table 3 shows the test results.

[0067]

[Table 3]

As a result of the test, in the first to third inventions,
It was confirmed that the durability of the bead portion was greatly improved.

[0069]

As described above, according to the first to third aspects of the present invention, the cords of the folded portion of the carcass ply and the cords of the carcass ply main body which are closest to the outer end of the bead apex rubber are provided. A portion is provided, and a gradually increasing region in which a distance between cords of the main body portion and the folded portion gradually increases outward in the tire radial direction is formed on the outer side of the proximity portion in the tire radial direction. Initial cracking, which is a starting point of separation at the end and the adjacent portion, can be suppressed for a long time, and the durability of the bead portion can be improved.

Further, in the invention according to claim 4, the folded portion has an inner portion in which at least the ply portion forming the gradually increasing region is disposed inside the ply portion in the tire axial direction.
By being covered with an insulation rubber different from a sidewall rubber having an outer portion disposed outside the ply portion in the tire axial direction, the folded portion can be prevented from coming into contact with the flexible sidewall portion. Further, the durability of the bead portion is improved.

According to the fifth aspect of the present invention, the insulation rubber is formed such that the inner portion and the outer portion are integrated at the outer end of the folded portion, and the rubber is located radially outward of the outer end of the folded portion. By having the tip end extending and tapering, the cord cut surface appearing at the outer end of the folded portion can be reliably prevented from coming into contact with the sidewall rubber, and the durability of the bead portion is further improved.

Further, according to the invention of claim 6, initial cracks and cracks between the cord reinforcing layer and the folded portion of the carcass ply can be suppressed for a long period of time, so that chafing of the bead portion can be effectively prevented.

According to the present invention, the folded portion of the carcass ply has an adjacent portion closest to the main body, a cord reinforcing layer is provided outside the carcass ply of the bead portion, and the end portion of the cord reinforcing layer is provided. By controlling the resistance, it is possible to enhance the trauma resistance of the bead portion and effectively suppress the separation at both ends of the cord reinforcing layer, thereby improving the durability of the bead portion.

[Brief description of the drawings]

FIG. 1 is a rim-assembled tire meridian sectional view showing an embodiment of the first invention.

FIG. 2 is a partial sectional view of a bead portion.

FIG. 3 is a partial cross-sectional view showing a rubber distribution of a bead portion.

FIG. 4 is a sectional view taken along line AA of FIG. 1;

FIG. 5 is a partial sectional view of a bead portion showing the embodiment of the first invention.

FIG. 6 is a partial cross-sectional view of a bead portion showing still another embodiment of the first invention.

FIG. 7 is a sectional view of a tire meridian in a standard state showing an embodiment of the second invention.

FIG. 8 is a partially enlarged view of FIG.

FIGS. 9A and 9B are cross-sectional views showing another embodiment of the cord reinforcing layer.

FIG. 10 is a partial cross-sectional view of a bead portion showing an embodiment of the third invention.

FIG. 11 is a partial sectional view of a bead portion showing another embodiment of the third invention.

FIG. 12 is a partial sectional view showing a conventional bead portion.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6A Carcass ply 6a Carcass ply main body 6b Carcass ply turnback part 8 Bead apex rubber 8t Outer end of bead apex rubber 10 Insulation rubber 10a Inner part 10b Outer part 10c Tip 11 Sidewall rubber 13, 20 Cord reinforcement layer 14 Outer portion 14t Outer end of outer portion 15 Involved portion 15t End portion of entrained portion 25 Second gradually increasing region X Closer portion Y Progressively increasing region G Parallel region BL Bead baseline

Continuation of the front page (72) Inventor Asayasu Shibata 471, Nishiiguchi, Higashikamiyoshi-cho, Kakogawa-shi, Hyogo (72) Inventor Kazumi Yamazaki 2-1-27, Daidominami, Higashiyodogawa-ku, Osaka-shi, Osaka

Claims (7)

[Claims] 1. A body portion extending from a tread portion to a bead core of a bead portion through a sidewall portion to a bead portion, and a bend core is provided integrally with the bead core so as to be folded from inside to outside in the tire axial direction. 70-9
A pneumatic tire having a carcass having a carcass ply arranged at an angle of 0 °, wherein the bead portion includes a bead apex rubber tapered and extends radially outward from a bead core in a tire radial direction. The bead apex rubber extends radially outward along the outer surface of the bead apex rubber in the tire axial direction, and the inter-cord distance (t), which is the distance between the carcass cord of the folded portion and the carcass cord of the main body, is increased. The carcass cord has a minimum value (tmin) of 0.15 to 7.0 times the diameter D of the carcass cord; , A pneumatic tire characterized by forming a gradually increasing region in which the inter-cord distance (t) gradually increases outward in the tire radial direction. 2. The method according to claim 1, wherein the bead portion is at least 0.4 times the height (h0) of the turn-back portion from the bead base line and 1.0 to 1.0.
At least a part of the range not more than twice includes the gradual increase region, and the height (h) of the gradual increase region from the bead baseline and the inter-cord distance (t) at this arbitrary height (h) The pneumatic tire according to claim 1, wherein the ratio (t / h) to the pneumatic tire is substantially constant, and the value is in the range of 0.01 to 0.07. 3. The bead portion includes the proximity portion in at least a part of a range from 1.1 to 1.5 times the height (ha) of the bead apex rubber from a bead base line, The adjacent portion forms a parallel region in which the carcass cords of the main body portion and the folded portion extend substantially in parallel when the inter-cord distance (t) continuously becomes the minimum value (tmin). Claim 1 or 2
The pneumatic tire as described. 4. The folded portion according to claim 1, wherein a ply portion forming at least the gradually increasing region has an inner portion disposed inside the ply portion in the tire axial direction, and an outer portion disposed outside the ply portion in the tire axial direction. 4. The rubber composition according to claim 1, wherein the insulation rubber is covered with an insulation rubber different from the side wall rubber, and the insulation rubber comprises one or two rubber compositions. Pneumatic tires. 5. The insulation rubber according to claim 1, wherein the inner portion and the outer portion are integrated at an outer end of the folded portion, and extend outward in the tire radial direction from the outer end of the folded portion and have a tapered end. The pneumatic tire according to claim 4, wherein the pneumatic tire has a tapered portion. 6. A body portion extending from a tread portion to a bead core of a bead portion through a sidewall portion to a bead portion and integrally provided with a fold portion which is folded back from the inside in the tire axial direction to the outside by the bead core, and the carcass cord is positioned with respect to the tire equator. 70-9
A pneumatic tire provided with a carcass having a carcass ply arranged at an angle of 0 °, wherein the bead portion includes a bead apex rubber tapering and extending radially outward from a bead core in a tire radial direction. The bead apex rubber extends outward in the tire radial direction along the outer surface of the bead apex rubber in the tire axial direction, and the inter-cord distance (t), which is the distance between the carcass cord of the folded portion and the carcass cord of the main body, is increased. The carcass cord has a diameter (D) of 0.15 to 7.0 times that of the carcass cord, and the bead portion is a tire of the folded portion. A cord reinforcement layer extending axially outward and inward and outward in the tire radial direction, the cord reinforcement layer having an outer end extending from the bead base line to the height of the folded portion ( o) of 0.15 times or more and 1.
While it is located at a height of 0 or less, its inner end extends at least up to the maximum width line of the cross section of the bead core, and the cord reinforcing layer extends in the tire radial direction from the bead base line to the outer end of the cord reinforcing layer. 5 of height F
In a region of 0% or more and 100% or less, a second inter-cord distance, which is a distance between the carcass cord of the folded portion and the reinforcing cord of the cord reinforcing layer, gradually increases outward in the tire radial direction. The second increasing region includes a ratio (j / f) of a height f in the tire radial direction from the bead base line and the inter-cord distance (j) at the height f. Is 0.01 to 0.13. 7. A body portion extending from the tread portion to the bead core of the bead portion through the sidewall portion to the bead portion, integrally provided with a folded portion which is folded back from the inside in the tire axial direction to the outside by the bead core, and wherein the carcass cord is positioned with respect to the tire equator. 70-9
A pneumatic tire having a carcass having a carcass ply arranged at an angle of 0 °, wherein the bead portion includes a bead apex rubber tapered and extends radially outward from a bead core in a tire radial direction. The bead apex rubber extends radially outward along the outer surface of the bead apex rubber in the tire axial direction, and the inter-cord distance (t), which is the distance between the carcass cord of the folded portion and the carcass cord of the main body, is increased. The carcass cord has an adjacent portion having a minimum value (tmin), and the minimum value (tmin) is set to 0.15 to 7.0 times the diameter D of the carcass cord. A cord reinforcement layer is provided, and the cord reinforcement layer extends outward in the tire radial direction along the tire axial direction outside of the folded portion. And a winding portion extending from the outer portion to the radially inner side of the tire and extending inside the bead core in the tire radial direction, and the outer end of the outer portion in the tire radial direction has a tire radius of the bead core. In the tire radial direction between the innermost point (Ci) in the tire direction and a distance equal to the maximum cross-sectional width (BW) of the bead core from the outermost point (Co) in the tire radial direction of the bead core. A straight line (K) drawn from the cross-sectional center of gravity (Z) of the bead core to the inside of the bead core perpendicular to the cross-section maximum width direction of the bead core; A pneumatic tire disposed in a region sandwiched by an axial line (N) extending inward in the tire axial direction from an outer end of the portion.