JP2002087019A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of preventing delamination between a 0 deg. belt layer constituting a belt layer and an angled belt layer. SOLUTION: Both end parts in the tire cross direction of the 0 deg. belt layer 30 constituting the belt layer 28 of the tire 10 are arranged separated from each other on the outside in the tire diametrical direction against a carcass 14. Consequently, it is possible to reduce a displacement difference of extension in the tire circumferential direction of the 0 deg. belt layer 30 and the angled belt layer 32 and to reduce shearing distortion between the 0 deg. belt layer 30 and the angled belt layer 32, and accordingly, it is possible to prevent delamination between the 0 deg. belt layer 30 and the angled belt layer 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic tire used particularly for heavy vehicles.

[0002]

2. Description of the Related Art As a belt layer used in a conventional heavy-duty pneumatic tire, a 0 ° belt layer having a cord extending in a circumferential direction of the tire and a tire equator line are used to maintain the internal pressure of the tire and bear the load. There is an interlaced belt composed of an angled belt layer having a slanted cord.

[0003] Among heavy-duty pneumatic tires, in particular, in a flat heavy-duty pneumatic tire having a large deflection with respect to the sidewall length, the tire comes into contact with the road surface, so that the tread surface of the tire has an arcuate shape in the contact area. , The angled belt layer expands and deforms in the tire circumferential direction. This elongation deformation increases as it approaches the end in the tire width direction. In addition, it becomes larger as it gets closer to the inside in the tire radial direction.

[0004] At this time, since the 0 ° belt layer has a cord extending in the tire circumferential direction, it is difficult for the 0 ° belt layer to expand and deform in the tire circumferential direction. I will. For this reason, a large shear strain occurs in the interlayer rubber.

[0005] This shear strain is maximum at the end of the angled belt layer in the tire width direction, and therefore, at the end of the angled belt layer in the tire width direction, the angle between the angled belt layer and the angled belt layer is 0 °.
There is a problem that delamination occurs with the belt layer.

[0006]

In view of the above, the present invention suppresses the difference in the circumferential displacement between the angled belt layer and the 0 ° belt layer in the tire circumferential direction, thereby reducing the angled belt layer and the 0 ° belt layer. ° An object of the present invention is to provide a pneumatic tire that can reduce shear strain generated between the tire and a belt layer and prevent delamination.

[0007]

In the pneumatic tire according to the present invention, a pair of bead cores, a carcass straddling the bead core in a toroidal shape, and a circumferentially adjacent to the carcass extending radially outward of the carcass. A first belt having a cord coated with a cord, and having a dimension in a tire width direction which is adjacent to an outer side of the first belt in a tire radial direction and which is different from a dimension of the first belt in a tire width direction; Pneumatic tire comprising a second belt rubber-coated with a cord inclined with respect to the tire, wherein both end portions in the tire width direction of the first belt are separated radially outward with respect to the carcass. The radius of the first belt at the tire equator is Rc, and the radius of the first belt at both ends in the tire width direction of the second belt is Re. When, and satisfies Rc <Re ......... the (A).

Next, the operation and effect of the pneumatic tire according to the first aspect will be described.

Conventional belt layers used for pneumatic tires, especially for heavy loads, include a 0 ° belt layer having a cord extending in the tire circumferential direction and an angled belt layer having a cord inclined with respect to the tire equator. There is an interlacing belt constructed.

[0010] Among heavy-duty pneumatic tires, in particular, in a flat heavy-duty pneumatic tire having a large deflection with respect to the sidewall length, the tire comes into contact with the road surface, so that the tread surface of the tire has an arcuate shape in the contact area. , The angled belt layer expands and deforms in the tire circumferential direction. This elongation deformation increases as it approaches the end in the tire width direction. In addition, it becomes larger as it gets closer to the inside in the tire radial direction.

At this time, since the 0 ° belt layer has a cord extending in the tire circumferential direction, it is difficult for the 0 ° belt layer to expand and deform in the circumferential direction of the tire. I will. For this reason, a large shear strain occurs in the interlayer rubber.

This shear strain is maximum at the end of the angled belt layer in the tire width direction, and therefore, at the end of the angled belt layer in the tire width direction, the angle between the angled belt layer and the angled belt layer is 0 °.
There is a problem that delamination occurs with the belt layer.

Here, in the present invention, the above configuration suppresses the deformation of the second belt extending in the tire circumferential direction, and at this time, the first belt hardly extends in the tire circumferential direction. A circumferential displacement difference due to a difference in tire circumferential elongation between both layers of the first belt and the second belt is reduced. As a result, shear strain can be reduced, and delamination between the first belt and the second belt can be suppressed.

The same effect can be obtained by jumping only the second belt outward in the tire radial direction. However, in order to jump up the second belt, a rubber is provided between the first belt and the second belt. Is not preferable because the adhesion between the first belt and the second belt deteriorates, and air becomes mixed between the layers during vulcanization.

In the present invention, when the rim is assembled (internal pressure 20 k
Pa).

In the pneumatic tire according to the present invention, the interlayer gauge which is the shortest distance between the cord of the first belt and the cord of the carcass at the tire equator line is G1, and the tire width of the second belt is G1. When an interlayer gauge that is the shortest distance between the cord of the first belt and the cord of the carcass at both ends in the direction is G2, the following satisfies G2 ≧ 1.3G1 (B). .

Next, the operation and effect of the pneumatic tire according to the second aspect will be described.

The interlayer gauge that is the shortest distance between the cord of the first belt and the cord of the carcass at the tire equator line is G1, and the cord of the first belt and the cord of the carcass at both ends in the tire width direction of the second belt. When the interlayer gauge that is the shortest distance from the second belt is G2, the deformation of the second belt in the tire circumferential direction can be more effectively suppressed by satisfying the expression (B). As a result, the shear strain generated between the first belt and the second belt can be reduced,
Delamination can be effectively suppressed.

In the pneumatic tire according to the third aspect, rubber is disposed between the carcass and the first belt,
The rubber gauge in the tire radial direction of the rubber at both ends in the tire width direction of the second belt is 0.5 mm or more and 4 mm.
It is characterized by the following.

Next, the operation and effect of the pneumatic tire according to claim 3 will be described.

By arranging the rubber between the carcass and the first belt, the first belt can be separated from the carcass, and the state of Rc <Re can be maintained even when the internal pressure is charged. Shear distortion between the first belt and the second belt can be suppressed.

Particularly, the rubber gauge in the tire radial direction of the rubber at both ends in the tire width direction of the second belt is 0.5 mm.
With the above, the shear strain between the first belt and the second belt can be sufficiently reduced.

Conversely, if the rubber gauge is less than 0.5 mm, the above-mentioned shear strain cannot be reduced sufficiently.
When the rubber gauge is 4 mm or more, the first belt and the second belt
This belt is too far outward in the tire radial direction, and the first belt and the second belt may be exposed before the tread is completely worn, which is inappropriate.

[0024] In the pneumatic tire according to the fourth aspect, the JIS hardness A of the rubber is such that when the JIS hardness of the coating rubber for coating the cords of the first belt and the second belt is B, B−30 ° ≦ A ≦ B (C)

Next, the operation and effect of the pneumatic tire according to claim 4 will be described.

The JIS hardness A of the rubber preferably satisfies the above formula (C) when the JIS hardness of the coating rubber for coating the cords of the first belt and the second belt is B.

Conversely, if the JIS hardness A of the rubber is lower than B-30 °, the deformation of the rubber itself increases and the rubber itself breaks, which is inappropriate.
If the hardness A is larger than B, the amount of heat generation increases due to the relative movement of the belt layer with respect to the rubber, and the durability against delamination decreases, which is inappropriate.

In the pneumatic tire according to the fifth aspect, when the radius of the first belt at a substantially intermediate portion between the tire equator line and the end in the tire width direction of the second belt is Rd, −Rd> Rd−Rc (D)

Next, the operation and effect of the pneumatic tire according to claim 5 will be described.

The part where the separation failure between the belt layers occurs is as follows:
Since it is the widthwise end portion of the second belt, the portion of the first belt that is desired to be located on the outer side in the tire radial direction is only the both widthwise end portions of the second belt. For this reason, it is not necessary to position the first belt at the substantially middle portion between the tire equator line and the end in the tire width direction of the second belt, particularly in the tire radial direction outside.

Therefore, by satisfying the above expression (D) as in the present invention, the first belt at the substantially intermediate portion between the tire equator line and the end in the tire width direction of the second belt is moved outward in the tire radial direction. Can be avoided. For this reason,
The rubber volume between the first belt and the carcass can be suppressed.

[0032] In the pneumatic tire according to claim 6, the first belt is provided at both ends in the tire width direction of the second belt.
When the radius Re of the first belt at the end in the tire width direction is Rw, Re> Rw... (E) is satisfied.

Next, the operation and effect of the pneumatic tire according to claim 6 will be described.

Since the tread surface of the tire has a curvature in the width direction, if the radius Rw of the first belt is too large, the widthwise end of the first belt will be located further outside in the tire radial direction. Therefore, the widthwise end of the first belt may be easily exposed to the outside of the tire due to wear of the tread surface.

Therefore, as in the present invention, by satisfying the above expression (E), it is possible to effectively prevent the end of the first belt in the tire width direction from being exposed.

Conversely, if Re ≦ Rw, the end of the first belt in the tire width direction is easily exposed to the outside, which is inappropriate.

[0037] In the pneumatic tire according to the seventh aspect, a circumferential groove extending in the tire circumferential direction is formed on the tread surface on the tire radial outside of the second belt, and the end of the first belt in the tire width direction is formed. Is the shortest distance from the portion to the line extending in the tire width direction substantially parallel to the tire tread surface through the groove bottom of the circumferential groove, and the shortest distance from the tire width direction end of the second belt to the line. When the distance is Te, Tw, Te ≧ 0.5 mm (F) is satisfied.

Next, the operation and effect of the pneumatic tire according to claim 7 will be described.

A circumferential groove extending in the tire circumferential direction is formed on the tread surface of the second belt on the tire radially outer side,
The shortest distance from the end of the first belt in the tire width direction to the line extending in the tire width direction substantially parallel to the tire tread surface through the groove bottom of the circumferential groove is defined as Tw, and the end of the second belt in the tire width direction is defined as Tw. Assuming that the shortest distance from the section to the line is Te, by satisfying the above expression (F), the tire width direction end of the first belt and the second belt are required until the tread surface is completely worn. Can be prevented from being exposed to the outside of the tire.

Conversely, if Tw, Te <0.5 mm,
By the time the tread surface is completely worn, the widthwise end of the first belt and the widthwise end of the second belt may be exposed to the outside of the tire, which is inappropriate.

In the pneumatic tire according to the eighth aspect, the radius of the carcass at the tire equator is Rc ′,
When the radius of the carcass at the end in the tire width direction of the second belt is Re ′, Rc ′> Re ′ (G) is satisfied, and the first belt in the tire width direction is satisfied. When the radius of the carcass at the end is Rw ', the following condition is satisfied: Rw'> Re '... (H).

Next, the operation and effect of the pneumatic tire according to claim 8 will be described.

By satisfying the above expressions (G) and (H) as in the present invention, the amount of radial growth of the carcass at the end in the tire width direction of the second belt at the time of filling the internal pressure is increased. For this reason, since the deformation of the second belt in the tire circumferential direction is further suppressed, delamination between the first belt and the second belt can be effectively prevented.

In the present invention, when the rim is assembled (internal pressure 20 k
The relationship under the condition of Pa) is shown.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic tire according to a first embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view of a pneumatic tire according to one embodiment of the present invention.

First, the overall structure of the pneumatic tire according to the present invention will be described.

As shown in FIG. 1, the pneumatic tire 10
(Hereinafter, simply referred to as “tire 10”.) Has a pair of bead cores 12 and a carcass 14 that straddles the pair of bead cores 12 in a toroidal manner. This carcass 14
The carcass ply 16 is constituted.

The carcass ply 16 is folded around the bead core 12 from the inside to the outside in the tire axial direction. Further, one carcass reinforcing layer 22 is provided in the tire axial direction inside of the carcass ply 16 in the vicinity of the folded portion to the bead core 12.

A side rubber layer 24 is formed outside the carcass 14 in the tire axial direction. On the other hand, an inner liner 35 is provided inside the carcass 14 in the tire axial direction.
Is provided.

As will be described later in detail, a belt layer 28 is disposed outside the carcass 14 in the tire radial direction.

A tread rubber layer constituting the tread 31 is provided outside the belt layer 28 in the tire radial direction. In the surface of the tread 31, a plurality of circumferential grooves 27 extending along the tire circumferential direction are formed.

Here, the configuration of the belt layer 28 and the rubber gauge of the tread 31 will be described in detail.

As shown in FIG. 1, the belt layer 28 includes two 0 ° belt layers 3 having cords extending in the tire circumferential direction.
0 (first belt) and two angled belt layers 32 (second belt) having cords inclined with respect to the tire equator line CL.
Belt) is a crossed belt layer.

More specifically, as shown in FIG.
4, a first 0 ° belt layer 30A is arranged adjacent to the carcass 14, but both ends in the tire width direction are arranged apart from the carcass 14.

A rubber 34 is disposed between the carcass 14 and the first 0 ° belt layer 30A. The JIS hardness A (°) of the rubber 34 is equal to the belt layer 28 (0
° If the JIS hardness of the coating rubber constituting the belt layer 30 and the angled belt layer 32) is B (°), it is set so as to satisfy B-30 ° ≦ A ≦ B (1) I have.

The rubber gauge in the tire radial direction of the rubber 34 at both ends in the tire width direction of the angled belt layer 32 is set to 0.5 mm or more and 4 mm or less.

Further, a second 0 ° belt layer 30B is arranged outside the first 0 ° belt layer 30A in the tire radial direction. The first 0 ° belt layer 30A and the second 0 ° belt layer 30B are set to have substantially the same dimensions in the tire width direction.

Further, a first angled belt layer 32A is disposed outside the second 0 ° belt layer 30B in the tire radial direction. The size of the first angled belt layer 32A in the tire width direction is set to be shorter than the size of the 0 ° belt layer 30 in the tire width direction.

Further, a second angled belt layer 32B is arranged outside the first angled belt layer 32A in the tire radial direction. The second angled belt layer 32B
Of the first angled belt layer 32
A is set to be shorter than the dimension of A in the tire width direction.

The rubber gauge of the tread 31 extends from the end (upper surface) of the first 0 ° belt layer 30A in the tire width direction through the groove bottom of the circumferential groove 27 and substantially parallel to the tire tread surface in the tire width direction. If the shortest radial distance from the tire width direction end (upper surface) of the first angled belt layer 32A to the line l is Te, then Tw, Te, .Gtoreq.0.5 (mm)... (2)

Here, the belt layer 28 which is a feature of the present invention is used.
Will be described.

As shown in FIG. 1, the radius of the first 0 ° belt layer 30A at the tire equator line CL (means the distance from the center of rotation to the center position of the first 0 ° belt layer 30A in the tire radial direction). The same shall apply hereinafter.) Is Rc, and the first angled belt layer 32 </ b> A at the both ends in the tire width direction is the first.
When the radius of the 0 ° belt layer 30A is represented by Re, Rc <Re... (3) is satisfied.

The first 0 in the tire equator line CL
The interlayer rubber gauge that is the shortest distance between the cord of the belt layer 30A and the cord (not shown) of the carcass 14 is G1, and the first 0 ° belt layer 30A at both ends in the tire width direction of the first angled belt layer 32A. G is the shortest distance between the cord of the carcass 14 and the cord of the carcass 14.
When G2 is set to 2, G2 ≧ 1.3G1 (4) is satisfied.

Further, when the radius of the first 0 ° belt layer 30A at a substantially intermediate portion between the tire equator line CL and the end portion in the tire width direction of the first angled belt layer 32A is Rd, Re-Rd > Rd-Rc (5)

The radius Re of the first 0 ° belt layer 30A at both ends in the tire width direction of the first angled belt layer 32A is the radius of the first 0 ° belt layer 30A at the end in the tire width direction. When Rw is set, Re> Rw (6) is satisfied.

Next, the radius of the carcass 14, which is a feature of the present invention, will be described.

The radius of the carcass 14 at the tire equator line CL (meaning the distance from the center of rotation to the center of the carcass in the tire radial direction; the same applies hereinafter) is defined as Rc ', and the first is Rc'.
When the radius of the carcass 14 at the end in the tire width direction of the angled belt layer 32A is represented by Re ′, Rc ′> Re ′ (7) is satisfied.

Next, the operation and effect of the pneumatic tire of this embodiment will be described in comparison with a conventional tire.

As a belt layer used in a conventional pneumatic tire especially for heavy load, a 0 ° belt layer having a cord extending in the tire circumferential direction and an angled belt layer having a cord inclined with respect to the tire equator are used. There is an interlacing belt constructed.

[0070] Among heavy-duty pneumatic tires, particularly in the case of flat heavy-duty pneumatic tires having a large deflection with respect to the side wall length, the tire is in contact with the road surface, so that the tread surface of the tire has an arcuate shape in the contact area. , The angled belt layer expands and deforms in the tire circumferential direction. This elongation deformation increases as it approaches the end in the tire width direction. In addition, it becomes larger as it gets closer to the inside in the tire radial direction.

At this time, since the 0 ° belt layer has a cord extending in the tire circumferential direction, it is difficult for the 0 ° belt layer to expand and deform in the tire circumferential direction. I will. For this reason, a large shear strain occurs in the interlayer rubber.

This shear strain is maximum at the end of the angled belt layer in the tire width direction, and therefore, at the end of the angled belt layer in the tire width direction, the shear distortion is 0 °.
There is a problem that delamination occurs with the belt layer.

Therefore, as in the present invention, both ends in the tire width direction of the belt layer 28 are arranged to be spaced apart from the carcass 14 in the tire radial direction and satisfy the above expression (3). Elongation of the angled belt layer 32 in the tire circumferential direction is suppressed.

As a result, the difference between the 0 ° belt layer 30 in the tire circumferential direction and the angled belt layer 32 in the tire circumferential direction can be reduced, and the difference between the 0 ° belt layer 30 and the angled belt layer 32 can be reduced. Can be reduced, and delamination can be suppressed.

A rubber (not shown) may be arranged between the 0 ° belt layer 30 and the angled belt layer 32, and only the angled belt layer 32 may be arranged to be separated from the carcass 14. In this case, the adhesiveness between the 0 ° belt layer 30 and the angled belt layer 32 becomes poor, and 0 °
This is inappropriate because there is a problem that air enters between the belt layer 30 and the angled belt layer 32.

Here, the interlayer rubber gauge which is the shortest distance between the cord of the first 0 ° belt layer 30A and the cord of the carcass 14 at the tire equator line CL is G1, and the tire width direction of the first angled belt layer 32A is G1. When the interlayer rubber gauge, which is the shortest distance between the cord of the first 0 ° belt layer 30A and the cord of the carcass 14 at both ends, is set to G2, the above equation (4) is satisfied, so that more effect is obtained. Thus, deformation of the angled belt layer 32 in the tire circumferential direction can be suppressed. As a result, the shear distortion generated between the 0 ° belt layer 30 and the angled belt layer 32 can be reduced, and delamination can be effectively suppressed.

When the radius of the first 0 ° belt layer 30A at a substantially intermediate portion between the tire equator line CL and the end in the tire width direction of the first angled belt layer 32A is Rd, the above equation ( 5) is set to satisfy
It is possible to avoid positioning the 0 ° belt layer 30 on the outer side in the tire radial direction at a substantially intermediate portion between the tire equator line CL of the angled belt layer 32 and the end portion in the tire width direction. Rubber volume between them can be suppressed.

The radius Re of the first 0 ° belt layer 30A at both ends in the tire width direction of the first angled belt layer 32A is the radius of the first 0 ° belt layer 30A at the tire width direction end. On the other hand, when Rw is satisfied, the above equation (6) is set so as to satisfy the following equation (6): On the contrary, if Re ≦ Rw, the thickness of the tread layer located outside the belt layer 28 in the tire radial direction Is thinner at the end of the 0 ° belt layer 30 in the tire width direction, and the end of the 0 ° belt layer 30 in the tire width direction is easily exposed to the outside of the tire, which is inappropriate.

The JIS hardness A (°) of the rubber 34 between the carcass 14 and the first 0 ° belt layer 30A is the same as that of the belt layer 28 (0 ° belt layer 30 and angled belt layer 3).
The JIS hardness of the coating rubber that constitutes 2) is B
(°), on the other hand, the JIS hardness A of the rubber 34 is set to satisfy B-3
If the angle is lower than 0 °, the deformation of the rubber itself increases and the rubber itself is destroyed, which is inappropriate. If the JIS hardness A of the rubber 34 is larger than B, the belt layer 28 with respect to the rubber 34 This is because the amount of heat generated by the relative movement increases, and the durability against delamination decreases and becomes inappropriate.

The rubber gauge in the tire radial direction of the rubber 34 at both ends in the tire width direction of the angled belt layer 32 is set to 0.5 mm or more and 4 mm or less. Conversely, the rubber gauge is set to less than 0.5 mm. This is because the above-mentioned shear strain cannot be sufficiently reduced.
mm or more, the 0 ° belt layer 30 and the angled belt layer 32 may be excessively outward in the tire radial direction, and the 0 ° belt layer 30 and the angled belt layer 32 may be exposed before the tread 31 is completely worn. This is because it becomes inappropriate.

The shortest distance from the end of the first 0 ° belt layer 30A in the tire width direction to the line 1 is Tw, and the shortest distance from the end of the first angled belt layer 32A in the tire width direction to the line 1 is Tw. When the distance is Te, the above equation (2)
Are set so as to satisfy
If e <0.5 mm, the end of the 0 ° belt layer 30 in the tire width direction and the end of the angled belt layer 32 in the width direction may be exposed to the outside of the tire before the tread surface is completely worn. This is because it is inappropriate.

Next, a pneumatic tire according to another embodiment of the present invention will be described.

Like the belt layer 52 of the pneumatic tire 50 shown in FIG. 2, compared to the belt layer 28 of the pneumatic tire 10 of the first embodiment, even if the belt layer 28 is separated from the carcass 14 from the inner side in the tire width direction. Good. In this embodiment, the belt layer 5
The rubber gauge of the rubber 54 located between the carcass 2 and the carcass 14 in the tire radial direction becomes substantially constant from the inside to the outside in the tire width direction.

Further, like the belt layer 62 of the pneumatic tire 60 shown in FIG.
The belt layer 28 and the carcass 1 are further separated from the carcass 14 from the inner side in the tire width direction as compared with the belt layer 28 of the
4 may be set so that the rubber gauge in the tire radial direction of the rubber 64 positioned between the rubber 4 and the rubber 64 gradually increases from the inside to the outside in the tire width direction.

Further, a portion of the belt layer 28 located near the end in the tire width direction, such as the carcass 72 of the pneumatic tire 70 shown in FIG. The end and the carcass 72 may be separated from each other.

In the present embodiment, the radius Rw ′ of the carcass 72 at the tire width direction end of the first 0 ° belt layer 30A constituting the belt layer 28 and the tire width direction end of the first angled belt layer 32A When the radius of the carcass 72 in the part is Re ', the setting is made so as to satisfy Rw'> Re '(8).

According to the present embodiment, by satisfying the above expression (8), the radial growth amount of the carcass 72 at the end in the tire width direction of the angled belt layer 32 at the time of filling the internal pressure is increased. For this reason, since the deformation of the angled belt layer 32 in the tire circumferential direction is further suppressed, the 0 ° belt layer 3
Delamination between the 0 and the angled belt layer 32 can be effectively prevented. (Test Example) The following tests were performed using the tires shown in FIGS.

Under the conditions of a tire size of 285 / 60R22.5, an internal pressure of 900 (kPa), and a load of 5000 (kgf), delamination between the 0 ° belt layer and the angled belt layer at the tire width direction end ( The distance traveled before the occurrence of a failure) was measured.

Here, as the belt layers of the tire, a first 0 ° belt layer, a second 0 ° belt layer, a first angled belt layer (R52 °), a second angle A crossed belt having a belt layer (L52 °) was used.
The JIS hardness of the coating rubber of the belt is 76 °.
It is.

The results of this test are shown in Tables 1 and 2 below.
Shown in

[0091]

[Table 1]

[0092]

[Table 2]

The “distance to failure occurrence” in Tables 1 and 2 is represented by an index with Comparative Example 1 as a reference (100).

[0094] As shown in Tables 1 and 2, it was found that the tire of each example had a longer running distance until failure than the tire of the comparative example. In particular, tires having a running distance of 120 or more before the occurrence of a failure have a high degree of satisfaction in the market.

[0095]

According to the pneumatic tire of the present invention, the displacement between the angled belt layer and the 0 ° belt layer is suppressed by suppressing the difference in the circumferential direction between the angled belt layer and the 0 ° belt layer. Can be reduced and delamination can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pneumatic tire according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a pneumatic tire according to another embodiment of the present invention.

FIG. 3 is a sectional view of a pneumatic tire according to another embodiment of the present invention.

FIG. 4 is a sectional view of a pneumatic tire according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 Pneumatic tire 12 Bead core 14 Carcass 28 Belt layer 30 First belt 31 Tread 32 Second belt 34 Rubber 52 Belt layer 62 Belt layer 64 Rubber 72 Carcass

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B60C 9/18 B60C 9/18 NG

Claims (8)

[Claims] 1. A pair of bead cores, a carcass straddling the bead core in a toroidal shape, a first belt adjacent to the carcass radially outward of the carcass and rubber-coated with a cord extending in a circumferential direction, the first belt, A second belt which is adjacent to the outer side in the tire radial direction of the belt, has a size in the tire width direction different from the size of the first belt in the tire width direction, and is rubber-coated with a cord inclined with respect to the equator line; Wherein both end portions in the tire width direction of the first belt are disposed apart from the carcass in the tire radial direction, and a radius of the first belt at a tire equator line. Where Rc is the radius of the first belt at both ends in the tire width direction of the second belt, and Rc <Re... (A) is satisfied. The pneumatic tire according to claim. 2. The interlayer gauge, which is the shortest distance between the cord of the first belt and the cord of the carcass at the tire equator line, is G1, and the first belt at both ends in the tire width direction of the second belt. 2. The pneumatic tire according to claim 1, wherein when an interlayer gauge that is a shortest distance between the cord of the carcass and the cord of the carcass is G2, G2 ≧ 1.3G1 (B) is satisfied. . 3. A rubber is disposed between the carcass and the first belt, and a rubber gauge in a tire radial direction of the rubber at both ends in a tire width direction of the second belt is 0.5 mm or more and 4 mm or more.
The pneumatic tire according to claim 1 or 2, wherein: 4. The JIS hardness A of the rubber is B-30 ° ≦ A ≦ B when the JIS hardness of the coating rubber for coating the cords of the first belt and the second belt is B. The pneumatic tire according to claim 3, wherein (C) is satisfied. 5. When the radius of the first belt at a substantially intermediate portion between the tire equator line and the end portion in the tire width direction of the second belt is Rd, Re-Rd> Rd-Rc ... The pneumatic tire according to any one of claims 1 to 4, wherein (D) is satisfied. 6. The radius Re of the first belt at both ends in the tire width direction of the second belt is expressed as: Re> Rw, where Rw is the radius of the first belt at the end portion in the tire width direction. The pneumatic tire according to any one of claims 1 to 5, which satisfies (E). 7. A circumferential groove extending in a tire circumferential direction is formed on a tread surface on a tire radially outer side of the second belt, and a groove from the tire width direction end of the first belt to the circumferential groove. When the shortest distance from the line extending through the bottom in the tire width direction substantially parallel to the tire tread surface is Tw, and the shortest distance from the tire width direction end of the second belt to the line is Te, The pneumatic tire according to any one of claims 1 to 6, wherein Tw, Te ≧ 0.5 mm (F) is satisfied. 8. When the radius of the carcass at the tire equator line is Rc ′ and the radius of the carcass at the end in the tire width direction of the second belt is Re ′, Rc ′> Re ′... (G), and when the radius of the carcass at the end in the tire width direction of the first belt is Rw ′, the following condition is satisfied: Rw ′> Re ′ (H) The pneumatic tire according to any one of claims 1 to 7, wherein