JP3393853B2 - Pneumatic tire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention substantially eliminates the conventional inner liner by providing the innermost carcass ply with the air pressure retaining force, and achieves weight reduction while maintaining durability. Regarding tires.

[0002]

2. Description of the Related Art In a tubeless pneumatic tire, an inner liner made of a low air permeable rubber composition is usually applied to the inside of a carcass in order to keep the internal pressure air airtight. However, even with such tires, further weight reduction is demanded in response to the recent strong demand for low fuel consumption.

Therefore, for example, Japanese Patent Laid-Open No. 6-15600
No. 7, JP-A-8-113007, etc., the topping rubber of the innermost carcass ply is formed of the low air permeability rubber composition, and the carcass ply is provided with an air retaining force. A tire having an inner liner-less structure without the inner liner has been proposed.

On the other hand, the carcass ply a is conventionally shown in FIG.
As shown in (A), a carcass cord is formed by using a long primary ply d formed by covering a cord array b in which the carcass cords are aligned parallel to the longitudinal direction with a topping rubber c. Specifically, this primary ply d is set to a desired angle α with respect to the length direction (for example, 75 to 9 for radial tires).
0 degree) and a length La corresponding to the width of the carcass ply a
While cutting into the cut pieces d1 ... With, the non-cut side ends de and de of each cut piece d1 are sequentially connected (primary joint j1).
By doing so, the long joint sheet h in which the carcass cords are arranged at the angle α with respect to the longitudinal direction is formed as the secondary ply f. Then, as shown in FIG. 8 (B), the secondary ply f is cut into a single circumferential length, and both circumferential ends fe and fe are connected (secondary joint j2) to thereby form the carcass ply. a is formed.

At this time, the primary joint j1 and the secondary joint j2 are usually provided with an end portion d as shown in FIG. 9 (A).
The lap joint g is formed by overlapping and crimping between e and de and between the end portions fe and fe.

[0006]

Therefore, in the tire having the inner linerless structure described above, the joining line g1 of the lap joint g is exposed on the inner surface of the tire. As a result, in the case of insufficient pressure bonding or poor rubber flow during vulcanization, cracks tend to occur starting from the joining line g1 and the air pressure retention and durability are significantly reduced.

Therefore, the inventor of the present invention, as shown in FIG. 9 (B), attaches a cover rubber sheet i as one of the secondary plies f to one surface of the splicing sheet h to form a lap splicing portion by the primary splicing. It was proposed to use pre-coated g. At this time, in order to suppress the weight increase due to the cover rubber sheet i, it is necessary to make the topping rubber c thin by an amount corresponding to the thickness thereof, and in order to further improve the air leak resistance, the cover rubber sheet i is required. As the above, it is desirable to use a highly compounded low air permeability rubber composition in which the compounding amount of halogenated butyl rubber or the like is higher than that of the topping rubber c.

However, the thinning of the topping rubber c increases the risk of the cover rubber sheet i coming into contact with the carcass cord due to the rubber flow during vulcanization, and this highly compounded low air permeability rubber composition is When it comes into contact with the carcass cord, it causes poor adhesion to the carcass cord and induces cord looseness, which causes new problems to be solved for durability.

Therefore, the present invention is based on the use of a rubber having a fluidity lower than that of the cover rubber sheet as the topping rubber for covering the carcass cord, and the carcass of the cover rubber sheet due to the rubber flow during vulcanization. It is possible to effectively prevent not only cracks originating from the joining line but also cord looseness by preventing contact with cords and achieving a weight reduction comparable to the conventional innerlinerless structure. At the same time, it is intended to provide a pneumatic tire capable of ensuring excellent durability and air pressure retention.

[0010]

In order to achieve the above object, the invention of a pneumatic tire according to claim 1 of the present invention is a primary ply in which a cord array in which carcass cords are aligned in parallel is covered with a topping rubber. By diagonally cutting and primary joining, a secondary ply formed by pasting a cover rubber sheet on one surface of the joining sheet has one circumferential length and by secondary joining at both ends in the circumferential direction, Alternatively, the splicing sheet has one circumference and is secondly spliced at both ends in the circumferential direction while being stuck on the cover rubber sheet which is wound around the forming drum in advance, so that the splicing sheet surrounds the tire inner cavity and is bridged between the bead cores. 1 or more carcass plies are formed, and the innermost carcass ply forms a tire cavity surface by the cover rubber sheet facing the tire cavity side, At least the inner portion of the inner portion of the topping rubber of the innermost carcass ply on the tire bore side and the outer portion opposite to the inner portion of the innermost carcass ply contains 50 to 90% by weight of a diene rubber and a halogenated butyl rubber or A first low air permeability rubber composition containing 10 to 50% by weight of a halide of isobutylene / paramethylstyrene copolymer, and the cover rubber sheet contains 0 to 40% by weight of a diene rubber. A halogenated butyl rubber or a halide of isobutylene / paramethylstyrene copolymer in an amount of 60 to 100% by weight.
Of the first low air-permeable rubber composition, the minimum torque T1 of the first low air-permeable rubber composition at 170 ° C. measured by a curast meter is set to the second low air-permeable rubber composition. The feature is that the minimum torque T2 of the product is 1.1 or more.

In the invention of claim 2, the outermost part of the innermost carcass ply is the same as the inner part.
Alternatively, it is characterized by being formed of a low air permeability rubber composition having the same composition or a rubber composition different from that of the inner portion containing a diene rubber.

In the invention of claim 3, the innermost carcass ply has a total rubber thickness from the inner edge of the carcass cord to the inner surface of the tire of 0.2 to 0.7 mm, and from the inner edge of the carcass cord. The rubber thickness up to the inner surface of the inner portion is 0.1 to 0.2 mm.

Further, in the invention of claim 4, the complex elastic modulus E * 1 of the first low air permeability rubber composition is 5.5 MP.
The complex elastic modulus E * 2 of the second low air permeability rubber composition is 5.0 MPa or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
This will be described together with the illustrated example. FIG. 1 shows a meridional section when the pneumatic tire of the present invention is a passenger car tire.

In the figure, a pneumatic tire 1 has a tread portion 2, sidewall portions 3 extending inward in the tire radial direction from both ends thereof, a bead core 5 embedded at an inner end of each sidewall portion 3. And a bead portion 4 formed. Further, a carcass 6 is bridged between the bead cores 5 and 5 in the tire 1, and a tough belt layer 7 is arranged outside the carcass 6 in the radial direction and inside the tread portion 2.

The belt layer 7 has two or more, in this example, two belt plies 7 in which highly elastic belt cords are inclinedly arranged at an angle of, for example, 10 ° to 35 ° with respect to the tire circumferential direction.
A case of being formed from A and 7B will be exemplified. The belt plies 7A and 7B are arranged in different directions so that the belt cords cross each other, and the triangle structure of the cords enhances the belt rigidity, and the tread portion 2 has a hoop effect. And reinforce.

Further, the carcass 6 is, as shown in FIG.
The carcass cord 10 is, for example, 75 in the tire circumferential direction.
It is formed from one or more carcass plies 9 arranged in this example at an angle α of 90 degrees. The carcass ply 9 includes a ply body 6A extending from the tread portion 2 to the side wall portion 3 to the bead core 5 of the bead portion 4, and in this example, is connected to the ply body portion 6A and the circumference of the bead core 5 is a tire. It has a so-called 1-0 structure having a ply turn-back portion 6B turned back from the outside in the axial direction. Depending on requirements, a so-called 2-0 structure using two carcass plies 9 or a so-called 1-1 structure can also be suitably adopted.

Here, as shown in FIG. 3, the carcass ply 9 is a long primary formed by covering a cord array 11 in which carcass cords 10 are aligned in parallel in the longitudinal direction with a topping rubber 12. The ply D is used as the original fabric. This primary ply D is cut into cut pieces D1 ... At the angle α with respect to the length direction and at a length La corresponding to the width of the carcass ply 9, and thereafter, the non-cut side of each cut piece D1. The joint sheet 16 of the cut piece D1 is formed by sequentially connecting the end portions De and De (primary joint J1).

In the innermost carcass ply 9A, in this embodiment, as shown in FIGS. 4 (A) and 4 (B), the joint sheet 16 and a thin cover rubber sheet attached to one surface thereof. The secondary ply F is formed by 17 and the secondary ply F is cut into a length of one circumference, and both ends Fe in the circumferential direction are connected to each other (secondary joint J2). An inner carcass ply 9A is formed.

In the carcass ply 9 other than the innermost one,
As in the conventional case, the joint sheet 16 is directly used as a secondary ply, and the circumferential plies of the secondary ply are connected to each other.

Further, in the tire 1 of the present invention, as shown in FIG.
As shown in (B), the innermost carcass ply 9A
The conventional inner liner is substantially eliminated by imparting air pressure retention to the. That is, the innermost carcass ply 9A forms the tire inner cavity surface HS by the cover rubber sheet 17 facing the tire inner cavity H side.

In order to impart the air pressure holding force, at least the inner portion 12i of the inner portion 12i of the topping rubber 12 and the opposite outer portion 12o of the topping rubber 12 is provided with a first low air permeability rubber. It is formed of the composition 13.

In this example, the outer portion 12o is exemplified by a non-low air permeability rubber composition 14 containing more than 90% by weight of a diene rubber as a rubber base material. Natural rubber, butadiene rubber, styrene-butadiene rubber, isoprene rubber,
Chloroprene rubber, acrylonitrile butadiene rubber and the like can be used alone or in combination.

The first low air permeability rubber composition 13
As a rubber base material, 50 to 90% by weight of the diene rubber, halogenated butyl rubber or isobutylene.
Paramethylstyrene copolymer halide 10-5
The one containing 0% by weight is used. Due to this, low air permeability and other rubber members and carcass cord 1
Achieving compatibility with 0 and adhesiveness. (Hereinafter, halogenated butyl rubber and halide of isobutylene / paramethylstyrene copolymer may be referred to as low air permeability rubber.) From the viewpoint of adhesiveness, the content of the diene rubber is within the above range. The amount is 65% by weight or more,
Further, the content of the low air permeable rubber is preferably 35% by weight or less.

As the halogenated butyl rubber, chlorinated butyl rubber and brominated butyl rubber can be used.

The halide of the isobutylene / paramethylstyrene copolymer is not particularly limited,
From the viewpoint of adhesiveness, the isobutylene content is 89 to 97.
%, Preferably 89 to 95% by weight, particularly preferably 89 to 93% by weight. As a commercially available halide of isobutylene / paramethylstyrene copolymer, for example, EXXPRO90- manufactured by Exxon Chemical Co., Ltd.
10, EXXPRO89-4, EXXPRO93-5 and the like.

In this example, in order to secure higher adhesiveness in the first low air permeability rubber composition 13, a tackifier is added and the use of a plasticizer is excluded. Examples of the tackifier include coumarone resin, phenol resin, terpene resin, petroleum hydrocarbon resin, rosin derivative, etc., and 1 to 10 parts by weight, and further 3 to 10 parts by weight based on 100% by weight of the rubber base material. %, More preferably 3 to 8% by weight is preferable from the viewpoint of adhesiveness. As the plasticizer, mineral oil-based softeners such as mineral oils and aroma oils, plant-based softeners, phthalic acid derivatives and the like are known, and are usually added to improve the processability and flexibility of rubber. However, in this example, it is not used because it tends to reduce the adhesiveness.

Next, the primary joint J1 and the secondary joint J
2 is an end portion D as shown in FIGS. 5 (A) and 5 (B).
It is carried out by overlapping and crimping between e and De and between the end portions Fe and Fe, whereby the lap joint portions 20 and 21 are formed.

In the case of the conventional inner linerless structure, the lap joint portions 20 and 21 have their joining lines 2
0A and 21A are exposed on the inner surface HS of the tire, and cracks are generated from the joining lines 20A and 21A as a starting point due to insufficient pressure bonding, insufficient rubber flow during vulcanization, or intrusion of a release agent. Easier to do.

However, in this example, as described above, the secondary ply F for forming the carcass ply 9A is composed of the joint sheet 16 and the thin cover rubber sheet 17 attached to one surface thereof, As shown in FIG. 5A, the exposed portion of the joining line 20A generated on the joint sheet 16 is
It can be covered and protected by the cover rubber sheet 17, and the generation of cracks due to the primary joint can be effectively suppressed.

Here, in order to suppress an increase in weight due to the cover rubber sheet 17, it is necessary to form the inner portion 12i as thin as the thickness thereof. Therefore, in this example, the rubber thickness T3 from the inner edge of the carcass cord 10 to the inner surface of the inner portion 12i is 0.1 to 0.
2 mm, and the rubber thickness T2 from the inner edge of the carcass cord 10 to the inner surface HS of the tire is set to 0.2 to 0, which is the same level as that of a tire having a conventional inner linerless structure.
It illustrates the preferred case of maintaining the range of 7 mm.

In order to secure sufficient air leak resistance even when the inner portion 12i is made thin, the cover rubber sheet 17 is made of a rubber having a lower air permeability than that of the first low air permeability rubber composition 13. The second low air permeability rubber composition 15 having an increased compounding amount is used.

This second low air permeability rubber composition 15
Contains 0 to 40% by weight of the diene rubber and 60 to 100% by weight of the low air permeability rubber, and exhibits excellent low air permeability. On the other hand, although the adhesiveness with the first low air permeability rubber composition 13 is maintained, the adhesive strength with the carcass cord 10 is extremely poor.

Therefore, when the second low air permeability rubber composition 15 comes into contact with the carcass cord 10 due to the rubber flow at the time of vulcanization, the cord looseness is induced to cause peeling damage and durability. It becomes an obstacle. In particular, the reduction of the rubber thickness T3 increases the risk of the contact.

Therefore, in the present invention, in order to prevent this contact, the minimum torque T1 of the first low air permeability rubber composition 13 at 170 ° C. measured by the curast meter.
Is 1.1 or more of the minimum torque T2 of the second low air permeability rubber composition 15. For details, JIS-K
According to "Vulcanization test by vibration type vulcanization tester (curast meter)" described in 6300, temperature 170 ° C, amplitude angle ±
The cross-linking curve is measured at 1 ° and a frequency of 100 / min, and the minimum torques T1 and T2 at that time are obtained and compared.

This minimum torque is an index of the fluidity of rubber during vulcanization. Therefore, the minimum torque ratio T1 / T
By setting 2 to 1.1 or more, the first low air permeability rubber composition 13 becomes the second low air permeability rubber composition 15
Is less likely to flow. That is, during vulcanization, the inner portion 12i is placed between the carcass cord 10 and the cover rubber sheet 17.
Can be stably interposed, and the contact between the carcass cord 10 and the cover rubber sheet 17 can be reliably prevented. Also the inner part 12
Since the thickness fluctuation due to vulcanization of i becomes small, the rubber thickness T
2, T3 is stabilized, and it becomes possible to stably secure an excellent air pressure holding force.

The upper limit of the ratio T1 / T2 is preferably 2.0 or less from the viewpoint of workability when the rubber is topped on the carcass cord or workability when the rubber sheet is covered by the carcass ply. Further, in this example, the difference between the minimum torques T1 and T2 is provided by adding a large amount of carbon by about 10% by weight.

After vulcanization, the complex elastic modulus E * 1 of the first low air permeability rubber composition 13 is 5.5 MPa.
The complex elastic modulus E * 2 of the second low air permeability rubber composition 15 is preferably 5.0 MPa or less. This is because if the complex elastic modulus E * 1 exceeds 5.5 MPa, the rigidity is too high and the bending fatigue resistance decreases, and if the complex elastic modulus E * 2 exceeds 5.0 MPa, the rigidity is too high. This is because the crack resistance is reduced. The complex elastic modulus is a value when a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. is used and the temperature is 70 ° C., the frequency is 10 Hz, the initial strain is 10%, and the dynamic strain is ± 1%.

Whether or not the cover rubber sheet 17 is provided is as follows.
Although it can be confirmed by the boundary line P with the inner portion 12i, it can also be determined by comparing the thicknesses TA and TB of the lap joint portions 20 and 21.

In the lap joint portion 21, the cover rubber sheet 17 increases the rubber volume in the lap joint portion 21 to promote rubber flow during vulcanization, as shown in FIG. 5B. As a result, the joint strength in the joint line 21A is increased, and the generation of cracks due to the secondary joint can be suppressed in the same manner. However, in order to more reliably suppress the generation of the cracks, the tire inner surface HS is
The bead cores 5, 5 covering the joining line 21A.
It is preferable to additionally provide a rubber strip layer 22 extending in the intermediate direction.

This rubber strip layer 22 is, in this example,
Thickness T1 is 0.1 to 0.5 mm and width W1 is 5 to 80
The formation of cracks is effectively suppressed by forming a thin strip of mm and covering and protecting the exposed portion of the joining line 21A. When the thickness T1 is less than 0.1 mm and the width W1 is less than 5 mm, the suppression effect is reduced, and conversely, the thickness T1 is
When 1 is greater than 0.5 mm and width W1 is greater than 80 mm, the weight is unnecessarily increased, and not only the merit of weight reduction due to the inner linerless structure is impaired but also the uniformity of the tire is adversely affected. . For this,
The width W1 is more preferably about 25 to 50 mm.

The rubber strip layer 22 is preferably formed of a low air permeable rubber composition from the viewpoint of air leak resistance, and at this time, the low air permeable rubber composition of the same or similar composition as the inner portion 12i is used. Or a low air permeability rubber composition having a different composition. Here, the “homogeneous composition” means that the types of rubbers constituting the rubber base material are the same but the compounding ratios thereof are different, and “different composition” means the type of rubbers constituting the rubber base material. It means something different in itself. The rubber strip layer 22 may be formed of a non-low air permeability rubber composition.

Further, in this example, as described above, the outer portion 1
Although the case where the non-low air permeability rubber composition 14 is used is illustrated in 2o, a low air permeability rubber composition having the same or the same composition as the inner portion 12i, or a low air permeability rubber composition having a different composition. It is also good to form it with a thing.

When the outer portion 12o is formed of the non-low air permeability rubber composition 14, the inner portion 1 is
The boundary line K between the 2i and the outer portion 12o may be located outside the inner edge of the carcass cord 10 as in this example.
Although it is preferable from the viewpoints of weight reduction and air leak resistance, when the outer portion 12o is formed of a low air permeable rubber composition, the boundary line K may be located inside the inner edge of the carcass cord 10. Good.

In the primary joint J1, as shown in FIG. 6, for example, the ends De may be joined together in a zipper shape by joining the end faces together. It is preferable that the cover rubber sheet 17 is attached to one surface and the joint portion 24 is covered.

Next, another example of the innermost carcass ply 9A is shown in FIG. In this example, first, the cover rubber sheet 17 is wound around a forming drum, and the splicing sheet 16 for one circumferential length is attached to the outer peripheral surface of the splicing sheet, and both ends of the splicing sheet 16 are secondarily spliced. It forms a ply 9A.

In this structure, the cover rubber sheet 17 is
By the joining line 2 of the primary joint J1 and the secondary joint J2
Both 0A and 21A are covered and protected.

Although a particularly preferred embodiment of the present invention has been described above in detail, the present invention is not limited to the illustrated embodiment and can be modified in various modes.

[0049]

EXAMPLES The tire size of the structure shown in FIG. 1 is 195.
A / 65R15 tire was prototyped based on the specifications of Tables 1 and 2, and the tire weight, air leak resistance (air pressure retention), and durability of each sample tire were measured, and the results were compared with conventional tires. It is described in Table 1. The composition of the rubber composition used in Tables 1 and 2 is shown in Table 3.

(1) Tire weight: The weight per tire is measured, and it is shown as an index with the conventional tire being 100. The smaller the value, the lighter the weight.

(2) Air leak resistance (air pressure retention): A test tire was mounted on a rim (15 × 6JJ),
In addition, the rate of decrease in internal pressure when the tire was naturally left for 90 days after being filled with the internal pressure (300 kPa) is represented by an index with the conventional tire being 100. The smaller the value, the better.

(3) Durability A test tire was mounted on a rim (15 × 6JJ) and filled with an internal pressure (190 kPa), and a load (6.
The running distance until damage to the outer surface of the tire was made to run at 96 kN) and speed (70 km / h). The larger the index, the better.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

As shown in the table, in the tires of the examples, it can be confirmed that the inner linerless structure can greatly improve the durability while making the most of the merit thereof.

[0057]

Since the present invention is constructed as described above,
It is possible to prevent contact between the cover rubber sheet and the carcass cord due to rubber flow during vulcanization, and effectively suppress not only cracks originating from the joining line but also cord loosening. While achieving a weight reduction comparable to the inner linerless structure, excellent durability and air pressure retention can be secured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a tire according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a secondary joint of the carcass ply.

FIG. 3 is a diagram illustrating a primary ply and a splicing sheet.

4A and 4B are diagrams illustrating a secondary ply and a carcass ply formed by the secondary ply.

5 (A) and 5 (B) are enlarged cross-sectional views showing a primary joint and a secondary joint.

FIG. 6 is a cross-sectional view showing another example of the primary joint.

FIG. 7 is a diagram showing another example of a carcass ply.

8A and 8B are diagrams illustrating a carcass ply formation process.

9 (A) and 9 (B) are cross-sectional views of a lap joint portion of a carcass ply for explaining conventional problems.

[Explanation of symbols]

5 bead core 9 Carcass ply 9A Innermost carcass ply 10 car cascode 11 code array 12 topping rubber 12i inner part 12o outer part 13 First low air permeability rubber composition 15 Second low air permeability rubber composition 16 joint sheets 17 Cover rubber sheet 20, 21 Lap joint D first ply F second ply J1 primary connection J2 secondary joint H Tire lumen HS tire inner surface

Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08L 23/28 C08L 23/28 (72) Inventor Yutaka Kuroda 3-6-9 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Sumitomo Rubber Industries Ltd. (56) References JP 2000-94903 (JP, A) JP 2000-272023 (JP, A) JP 10-244602 (JP, A) JP 4-278336 (JP, A) JP 7-9807 (JP, A) JP-A-10-193926 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 1/00 B60C 5/14 B60C 9/04

Claims (4)

(57) [Claims] 1. A cover rubber sheet is attached to one surface of a splicing sheet obtained by diagonally cutting a primary ply obtained by covering a cord array body in which carcass cords are aligned in parallel with a topping rubber and performing primary splicing. The secondary ply formed by the method described above has a one-round length and is secondarily spliced at both ends in the circumferential direction, or the spliced sheet has a one-round length and is affixed to a cover rubber sheet previously wound around a molding drum. By making secondary splices at both ends in the circumferential direction, one or more carcass plies that surround the tire inner cavity and are bridged between the bead cores are formed, and the innermost carcass ply is located on the tire inner cavity side. The inner surface of the innermost carcass ply of the topping rubber and the inner side of the tire inner side of the topping rubber are formed by the cover rubber sheet directed toward the inner side of the tire. Of at least the inner portion of the outer portion opposite to 50 to 50% of the diene rubber.
90% by weight of halogenated butyl rubber or a halide of isobutylene / paramethylstyrene copolymer
0 to 50% by weight of the first low air permeable rubber composition, and the cover rubber sheet is 0 to 40 diene rubber.
60% by weight of halogenated butyl rubber or halide of isobutylene / paramethylstyrene copolymer.
100% by weight of the second low air permeability rubber composition, and the first low air permeability rubber composition, the minimum torque T1 at 170 ℃ measured by the curast meter,
A pneumatic tire having a minimum torque T2 of the second low air permeability rubber composition of 1.1 or more. 2. The innermost carcass ply is made of a low air-permeable rubber composition in which the outer portion has the same or similar composition as the inner portion, or a rubber composition different from the inner portion containing a diene rubber. The pneumatic tire according to claim 1, wherein the pneumatic tire is formed. 3. The innermost carcass ply has a total rubber thickness from the inner edge of the carcass cord to the inner surface of the tire of 0.
2 to 0.7 mm, and the rubber thickness from the inner edge of the carcass cord to the inner surface of the inner portion is 0.1 to 0.2 mm.
The pneumatic tire according to claim 1 or 2, wherein 4. The complex elastic modulus E * 1 of the first low air permeable rubber composition is 5.5 MPa or less, and the complex elastic modulus E * 2 of the second low air permeable rubber composition is , 5.0M
It is Pa or less, The pneumatic tire of Claim 1, 2 or 3 characterized by the above-mentioned.