JP2002103910A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability in an inner linerless structure. SOLUTION: An innermost carcass ply 9A is formed by using a secondary ply F formed by adhering a cover rubber sheet 17 to one face of a joint sheet 16 formed by diagonally cutting a primary ply D formed by coating a cord array 11 with the topping rubber 12, and primarily joining he same J1. A tire inner cavity face HS is formed by the cover rubber sheet 17. At least an inner part 12i of the topping rubber 12, and the cover rubber sheet 17 are made of first and second low air permeable rubber compositions 13 and 15. A ratio To1/To2 of minimum torques To1, To2 at 170 deg.C by a curastometer, of the first and second low air permeable rubber compositions 13 and 15 is 1.1 or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic pneumatic pump in which the innermost carcass ply is provided with a pneumatic holding force, thereby substantially eliminating the conventional inner liner and achieving 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 adhered to the inside of a carcass in order to keep the internal pressure air tight. However, even with such tires, further reduction in weight has been demanded in response to recent demands for low fuel consumption.

For this purpose, for example, Japanese Patent Application Laid-Open No. 6-15600
No. 7, JP-A-8-113007 and the like, by forming a topping rubber of the innermost carcass ply with the low air-permeable rubber composition and giving the carcass ply an air holding power. A tire having an inner linerless structure in which the inner liner is eliminated has been proposed.

On the other hand, a carcass ply a is conventionally
As shown in (A), a long primary ply d formed by covering a cord array b in which carcass cords are aligned in parallel in the longitudinal direction with a topping rubber c is used as a raw material. Specifically, the primary ply d is set at a desired angle α with respect to the length direction (for example, 75 to 9 in a radial tire).
0 °) and the length La corresponding to the width of the carcass ply a
Is cut into pieces d1..., While the ends de on the non-cut side of each cut piece d1 are sequentially connected (primary joint j1).
By doing so, the long spliced 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. 8B, the carcass ply f is cut by cutting the secondary ply f at one circumference and connecting between both ends fe and fe in the circumferential direction (secondary joint j2). a.

At this time, the primary joint j1 and the secondary joint j2 usually have an end d as shown in FIG.
By overlapping and crimping between e and de and between the end portions fe and fe, a lap joint portion g is formed.

[0006]

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

Therefore, as shown in FIG. 9 (B), the present inventor has attached a cover rubber sheet i to one surface of the joining sheet h as the secondary ply f, and It was proposed to use g which had been previously coated and protected. At this time, in order to suppress the weight increase due to the cover rubber sheet i, it is necessary to reduce the thickness of the topping rubber c by an amount corresponding to the thickness thereof. It is desired to use a highly blended low air-permeable rubber composition in which the blending amount of halogenated butyl rubber or the like is higher than that of the topping rubber c.

However, the reduction in the thickness 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. When contacting the carcass cord, a new problem to be solved with respect to durability arises, such as inferior adhesion to the carcass cord to induce cord loose.

Therefore, the present invention is based on the fact that a fluid rubber having a lower fluidity than that of the cover rubber sheet is used as the topping rubber for covering the carcass cord, and the carcass of the cover rubber sheet is caused by the rubber flow during vulcanization. It is possible to effectively prevent not only the occurrence of cracks and the like from the joint line, but also the occurrence of cord looseness, such as preventing contact with the cord, achieving a weight reduction comparable to the conventional inner linerless structure. It is another object of the present invention to provide a pneumatic tire that can ensure excellent durability and pneumatic holding power.

[0010]

In order to achieve the above object, the invention of a pneumatic tire according to claim 1 of the present invention is directed to a primary ply in which a cord array in which carcass cords are arranged in parallel is covered with topping rubber. , A secondary ply formed by attaching a cover rubber sheet to one surface of a joining sheet formed by diagonally cutting and primary joining is made to have a one-circle length, and secondary joining is performed at both ends in the circumferential direction. Alternatively, the spliced sheet is made to have one circumference, and is attached to a cover rubber sheet pre-wound on a forming drum, and secondarily spliced at both ends in the circumferential direction, so that the spliced sheet is bridged between the bead cores around the tire cavity. Forming one or more carcass plies, and the innermost carcass ply forms a tire lumen surface with the cover rubber sheet facing the tire lumen side, At least the inner portion of the innermost portion of the innermost carcass ply on the tire cavity side of the topping rubber and the outer portion opposite thereto is 50 to 90% by weight of the diene rubber and halogenated butyl rubber or The cover rubber sheet comprises a first low air permeable rubber composition containing 10 to 50% by weight of a halide of an isobutylene / paramethylstyrene copolymer, and the cover rubber sheet contains 0 to 40% by weight of a diene rubber. And 60 to 100% by weight of a halogenated butyl rubber or a halide of isobutylene / paramethylstyrene copolymer.
The minimum torque T1 of the first low air-permeable rubber composition at 170 ° C. measured by a curast meter is determined by the second low air-permeable rubber composition. The minimum torque T2 of the object is 1.1 or more.

In the invention according to claim 2, the innermost carcass ply has an outer portion which is the same as the inner portion,
Alternatively, it is characterized by being formed of a low air-permeable rubber composition of the same composition or a rubber composition different from the inner portion containing a diene rubber.

In the invention according to 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 has a thickness from the inner edge of the carcass cord. The thickness of the rubber up to the inner surface of the inner portion is 0.1 to 0.2 mm.

Further, in the invention of claim 4, the first low air-permeable rubber composition has a complex elastic modulus E * 1 of 5.5 MPa.
a, and the complex elastic modulus E * 2 of the second low air permeable rubber composition is 5.0 MPa or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described.
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, and a bead core 5 embedded at an inner end of each sidewall portion 3. And a bead portion 4 having the above configuration. Further, a carcass 6 is bridged between the bead cores 5 and 5 on the tire 1, and a tough belt layer 7 is disposed radially outside the carcass 6 and inside the tread portion 2.

The belt layer 7 is composed of two or more belt ply members 7 in which highly elastic belt cords are arranged at an angle of, for example, 10 ° to 35 ° with respect to the tire circumferential direction.
A and 7B are exemplified. The belt plies 7A and 7B are arranged in different directions so that the belt cords intersect each other between the plies, thereby increasing the belt rigidity by a triangle structure of the cords, and having a tag effect with substantially the entire width of the tread portion 2. And reinforce.

The carcass 6, as shown in FIG.
The carcass cord 10 is, for example, 75
It is formed from one or more carcass plies 9 arranged at an angle α of up to 90 degrees, in this example one carcass ply 9. The carcass ply 9 includes a ply body 6A extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3, and in the present example, the ply body portion 6A is connected to the ply body portion 6A and the bead core 5 is rotated around the tire. It has a so-called 1-0 structure having a ply turnup portion 6B that is turned inward from the outside in the axial direction. In addition, what is called a 2-0 structure using two carcass plies 9 and 9 or what is called a 1-1 structure can also be suitably employ | adopted by request.

Here, as shown in FIG. 3, the carcass ply 9 is formed by covering a cord array 11 in which carcass cords 10 are aligned in parallel along a longitudinal direction with a topping rubber 12. The ply D is formed as a raw material. The 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 is cut. Are sequentially connected (primary joint J1) between the end portions De, and the joint sheet 16 of the cut piece D1 is formed.

In the innermost carcass ply 9A, in the present embodiment, as shown in FIGS. 4A and 4B, the joining sheet 16 and a thin cover rubber sheet attached to one surface thereof are provided. 17, a secondary ply F is formed, the secondary ply F is cut at one circumference, and both ends Fe in the circumferential direction are connected (secondary joint J2) to form the secondary ply F. An inner carcass ply 9A is formed.

In the carcass ply 9 other than the innermost one,
As in the prior art, the joint sheet 16 is directly used as a secondary ply, and the two ends of the secondary ply in the circumferential direction are connected.

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

In order to provide the air pressure holding force, at least the inner part 12i of the inner part 12i of the topping rubber 12 and the opposite outer part 12o is made of a first low air permeable rubber. The composition 13 is used.

In this embodiment, a case where a non-low air-permeable rubber composition 14 containing more than 90% by weight of a diene rubber as a rubber base material is used for the outer portion 12o. 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
Is used as a rubber base material in an amount of 50 to 90% by weight of the diene rubber and halogenated butyl rubber or isobutylene.
10 to 5 of halide of paramethylstyrene copolymer
0% by weight. Thereby, low air permeability and other rubber members and carcass cord 1
It is compatible with the adhesiveness to zero. (Hereinafter, a halogenated butyl rubber and a halide of an isobutylene / paramethylstyrene copolymer may be referred to as a low air-permeable rubber.) From the viewpoint of adhesiveness, the content of the diene rubber is within the above range. The amount is at least 65% by weight,
It is preferable that the content of the low air permeable rubber is 35% by weight or less.

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

The isobutylene / paramethylstyrene copolymer halide 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. Examples of commercially available halides of isobutylene / paramethylstyrene copolymer include, for example, EXXPRO90- manufactured by Exxon Chemical Co., Ltd.
10, EXXPRO89-4 and EXXPRO93-5.

In this example, in order to ensure higher adhesiveness in the first low air permeable rubber composition 13, a tackifier is added and the use of a plasticizer is excluded. Examples of the tackifier include a coumarone resin, a phenol resin, a terpene resin, a petroleum hydrocarbon resin, a rosin derivative and the like, 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, from the viewpoint of adhesiveness. Also, as the plasticizer, mineral oil-based softeners such as mineral oil and aroma oil, plant-based softeners, phthalic acid derivatives and the like are known, and are usually added for improving 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 D as shown in FIGS. 5 (A) and 5 (B).
This is carried out by overlapping and crimping between e and De and between the ends Fe and Fe, thereby forming the spliced portions 20 and 21.

In the case of the conventional inner linerless structure, the joining lines 2
0A and 21A are exposed on the tire inner surface HS, and cracks occur starting from the joining lines 20A and 21A due to insufficient pressure bonding, insufficient rubber flow during vulcanization, or infiltration of a release agent. Easier to do.

However, in this embodiment, as described above, the secondary ply F for forming the carcass ply 9A is composed of the joining sheet 16 and the thin cover rubber sheet 17 stuck on one surface thereof. As shown in FIG. 5A, the exposed portion of the joining line 20A generated in the joining 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 thinner by a thickness corresponding to the thickness. 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 set to 0.1 to 0.
The thickness of the rubber T2 from the inner edge of the carcass cord 10 to the tire cavity surface HS is reduced to the range of 2 to 0.2 mm, which is the same level as that of a conventional tire having an inner linerless structure.
It illustrates a preferred case where it is maintained in the range of 7 mm.

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

This second low air permeable rubber composition 15
Comprises 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 permeable rubber composition 13 is maintained, the adhesive strength with the carcass cord 10 is very poor.

Therefore, when the second low air permeable rubber composition 15 comes into contact with the carcass cord 10 due to the rubber flow at the time of vulcanization, the rubber composition induces cord looseness and leads to exfoliation damage such as progress of peeling damage. It is an obstacle. In particular, the risk of the contact increases due to the decrease in the rubber thickness T3.

Therefore, in the present invention, in order to prevent this contact, the minimum torque T1 of the first low air permeable rubber composition 13 at 170 ° C. measured by a curastometer is measured.
Is set to 1.1 or more of the minimum torque T2 of the second low air permeable rubber composition 15. For details, see JIS-K
Temperature 170 ° C, amplitude angle ± according to “Vulcanization test using vibration type vulcanization tester (curast meter)” described in 6300
The bridging curve is measured at 1 ° and a frequency of 100 / min, and the minimum torques T1 and T2 at that time are determined and compared.

This minimum torque is an index of the fluidity of the rubber during vulcanization. Therefore, the minimum torque ratio T1 / T
2 is set to 1.1 or more, the first low air permeable rubber composition 13 becomes the second low air permeable rubber composition 15.
It becomes harder to flow. That is, during vulcanization, the inner portion 12i is located between the carcass cord 10 and the cover rubber sheet 17.
Are stably interposed, and the contact between the carcass cord 10 and the cover rubber sheet 17 can be reliably prevented. Also inner part 12
Since the thickness fluctuation due to the vulcanization of i becomes small, the rubber thickness T
2. T3 is stabilized, and it is 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 topping the carcass cord with rubber or workability when covering the rubber sheet on the carcass ply. In this example, a difference is provided between the minimum torques T1 and T2, for example, by blending the carbon amount by about 10% by weight.

After vulcanization, the first low air permeable rubber composition 13 has a complex elastic modulus E * 1 of 5.5 MPa.
The complex elastic modulus E * 2 of the second low air-permeable rubber composition 15 is preferably 5.0 MPa or less. This is because when the complex elastic modulus E * 1 exceeds 5.5 MPa, the rigidity is too high and the bending fatigue property is reduced. When 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 viscoelastic 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%.

The presence or absence of the cover rubber sheet 17 is determined by
Although it can be confirmed by the boundary line P with the inner portion 12i, it can also be determined by comparing the respective thicknesses TA and TB of the overlapping portions 20 and 21.

The cover rubber sheet 17 in the spliced portion 21 increases the rubber volume in the spliced portion 21 as shown in FIG. 5B, and promotes the rubber flow during vulcanization. As a result, the joining strength at the joining line 21A is increased, and the occurrence of cracks due to the secondary joint can be similarly suppressed. However, in order to more reliably suppress the occurrence of cracks, the tire inner surface HS is
The bead cores 5, 5 covering the joining line 21A
It is preferable to add a rubber strip layer 22 extending in the intervening direction.

In this embodiment, the rubber strip layer 22
The thickness T1 is 0.1 to 0.5 mm and the width W1 is 5 to 80.
By forming and protecting the exposed portion of the joining line 21A in a thin strip shape of mm, cracks can be effectively suppressed. If the thickness T1 is less than 0.1 mm and the width W1 is less than 5 mm, the suppression effect is reduced, and
If 1 is larger than 0.5 mm and the width W1 is larger than 80 mm, the weight is unnecessarily increased, and not only does the advantage of weight reduction due to the inner linerless structure be impaired, but also adversely affects the uniformity of the tire. . 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. At this time, a low air permeable rubber composition having the same or the same composition as the inner portion 12i is used. Or a low air permeable rubber composition of a different composition. Here, the “homogeneous composition” means the same kind of rubber constituting the rubber base material and the compounding ratio thereof is different, and the “heterogeneous composition” means the type of rubber constituting the rubber base material It means something different in itself. The rubber strip layer 22 may be formed of a non-low air-permeable rubber composition.

In this embodiment, as described above, the outer portion 1
Although the case where the non-low air permeability rubber composition 14 is used in 2o is exemplified, the low air permeability rubber composition having the same or the same composition as the inside portion 12i, or the low air permeability rubber composition having a different composition is used. It may be formed by an object.

When the outer portion 12o is formed of the non-low air permeable rubber composition 14, the inner portion 1o
The boundary line K between 2i and the outer portion 12o may be located outside the inner edge of the carcass cord 10 as in this example.
Although preferred from the viewpoint 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, for example, as shown in FIG. 6, the ends De, De may be joined to each other in a zipper shape with their end faces attached to each other. It is preferable that a cover rubber sheet 17 is stuck on one surface to cover the joint portion 24.

Next, another example of the innermost carcass ply 9A is shown in FIG. In this example, the cover rubber sheet 17 is first wound around a forming drum, and both ends of the cover rubber sheet 17 are secondarily joined while attaching the joining sheet 16 for one circumferential length on the outer peripheral surface thereof. The ply 9A is formed.

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

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment, but may be implemented in various forms.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A tire having the structure shown in FIG.
/ 65R15 tires were prototyped based on the specifications in Tables 1 and 2, and the tire weight, air leak resistance (air pressure retention), and durability of each test tire were measured, and the results were compared with conventional tires. It is described in Table 1. Table 3 shows the composition of the rubber composition used in Tables 1 and 2.

(1) Tire weight: The weight per tire is measured, and is indicated by an index with the conventional tire being 100. Smaller values are lighter.

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

(3) Durability The test tire was mounted on a rim (15 × 6JJ), filled with an internal pressure (190 kPa), and loaded on a drum (6.
The tire was run at a speed of 96 km / h and at a speed of 70 km / h, and the running distance until the outer surface of the tire was damaged was represented by an index when the conventional tire was set to 100. The larger the index, the better.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

As shown in the table, it can be confirmed that the durability of the tire according to the embodiment can be greatly improved while taking advantage of the inner linerless structure.

[0057]

As described above, the present invention is constituted,
It is possible to effectively prevent not only the occurrence of cracks and the like from the joint line but also the generation of cord loose, such as preventing the cover rubber sheet from contacting with the carcass cord due to the rubber flow during vulcanization. While achieving weight reduction comparable to the inner linerless structure, excellent durability and air pressure retention can be ensured.

[Brief description of the drawings]

FIG. 1 is a 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 joining sheet.

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

FIGS. 5A and 5B are cross-sectional views showing a primary joint and a secondary joint in an enlarged manner.

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

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

FIGS. 8A and 8B are diagrams illustrating a process of forming a carcass ply.

FIGS. 9A and 9B are cross-sectional views of overlapping portions of a carcass ply for explaining a conventional problem.

[Explanation of symbols]

 Reference Signs List 5 bead core 9 carcass ply 9A innermost carcass ply 10 carcass cord 11 cord arrangement body 12 topping rubber 12i inner part 12o outer part 13 first low air-permeable rubber composition 15 second low air-permeable rubber composition 16 Joint sheet 17 Cover rubber sheet 20, 21 Lap joint D Primary ply F Secondary ply J1 Primary joint J2 Secondary joint H Tire bore HS Tire bore

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 23/28 C08L 23/28 (72) Inventor Kano Kawai 3-6 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Prefecture No. 9 Sumitomo Rubber Industries, Ltd. (72) Inventor Yutaka Kuroda 3-6-9, Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo F-term in Sumitomo Rubber Industries, Ltd. 4J002 AC011 AC031 AC061 AC071 AC081 AC091 BB242 BC112

Claims (4)

[Claims] 1. A cover rubber sheet is attached to one surface of a joining sheet formed by diagonally cutting and priming a primary ply in which a cord arrangement body in which carcass cords are aligned in parallel and covered with topping rubber is subjected to primary joining. The secondary ply formed by the above is made to have a one-circle length, and secondly spliced at both ends in the circumferential direction. Or, the spliced sheet is made to have a one-circle length, and is pasted on a cover rubber sheet previously wound around a forming drum. By performing secondary joining at both ends in the circumferential direction while forming, one or more carcass plies that are bridged between the bead cores around the tire lumen are formed, and the innermost carcass ply is located on the tire lumen side. A tire inner cavity surface with the cover rubber sheet directed to the inner side of the tire inner cavity side of the topping rubber of the innermost carcass ply. At least the inner portion of the outer portion opposite to the outer portion of the diene rubber 50-
90% by weight and 1 of halogenated butyl rubber or a halide of isobutylene / paramethylstyrene copolymer
And the cover rubber sheet comprises a diene-based rubber of 0 to 40% by weight.
% By weight, and 60 to 60% by weight of the halogenated butyl rubber or the
100% by weight, and the minimum torque T1 of the first low air permeable rubber composition at 170 ° C. measured by a curastometer is as follows:
A pneumatic tire, wherein the minimum torque T2 of the second low air permeable rubber composition is 1.1 or more. 2. The innermost carcass ply is made of a low air-permeable rubber composition whose outer portion is the same as or similar to 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 not more than 5.5 MPa. , 5.0M
The pneumatic tire according to claim 1, 2 or 3, wherein the pressure is Pa or less.