JP2009078589A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of combining operation stability and riding comfort within a wide range of setting without reducing its durability. <P>SOLUTION: In the pneumatic tire whose mounting direction for mounting to a vehicle is specified, a carcass layer is divided into right and left, a vehicle-outside carcass layer 6 and a vehicle-inside carcass layer 7. 300% modulus Mo of a coat rubber 12 of the vehicle-outside carcass layer 6 is set to 13.5-18.5 MPa, 300% modulus Mi of a coat rubber 13 of the vehicle-inside carcass layer 7 is set to 11.0-15.5 MPa, and the modulus Mo is made to be larger than the modulus Mi by 1.3 MPa or more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can achieve both steering stability and ride comfort in a wide setting range without impairing durability.

  In order to improve the handling stability of the pneumatic tire, the rigidity of the side portion may be increased. However, there is a problem that riding comfort is reduced due to the increase in rigidity of the side portion. Conversely, in order to improve the ride comfort, the rigidity of the side portion may be lowered, but the steering stability is lowered.

  Therefore, Patent Document 1 specifies the tire mounting direction (the vehicle outer side and the vehicle inner side) at the time of vehicle mounting, and the side rigidity is set to the vehicle outer side as a countermeasure for achieving both the handling stability and the riding comfort of such a pneumatic tire. It is proposed to make a difference between the vehicle and the inside. That is, when the carcass layer is folded around the bead core from the inside of the tire to the outside, the folding direction is different between the outside of the vehicle and the inside of the vehicle, and the intersection angle of the carcass cord formed by the folded portion with respect to the carcass layer body is greater than the inside of the vehicle. By increasing the outside of the vehicle, the side rigidity on the outside of the vehicle is increased and the side rigidity on the inside of the vehicle is decreased.

However, in pneumatic tires, the folded height of the carcass layer is extended due to the problem of stress concentration at the folded end and damage to the side when extended to the flex zone where the repeated deformation of the side is large. The possible range is limited. For this reason, it has been impossible to adjust and set steering stability and ride comfort in a wide range.
JP 2007-83914 A

  An object of the present invention is to provide a pneumatic tire that can achieve both steering stability and ride comfort in a wide setting range without impairing durability.

  A pneumatic tire according to a first aspect of the present invention that achieves the above object is a pneumatic tire in which a mounting direction at the time of mounting on a vehicle is specified, wherein a carcass layer is divided into a vehicle outer carcass layer and a vehicle inner carcass layer. The 300% modulus Mo of the coat rubber of the vehicle outer carcass layer is set to 13.5 to 18.5 MPa, the 300% modulus Mi of the coat rubber of the vehicle inner carcass layer is set to 11.0 to 15.5 MPa, and the modulus Mo is set. Is made larger than the modulus Mi by 1.3 MPa or more.

  A pneumatic tire according to a second aspect of the present invention is a pneumatic tire in which a mounting direction at the time of vehicle mounting is specified, wherein a carcass layer is divided into a vehicle outer carcass layer and a vehicle inner carcass layer on the left and right sides, and the vehicle outer carcass is formed. The rubber hardness Ho of type A conforming to JIS K6253 of the layer coating rubber is set to 62 to 72, the rubber hardness Hi of the coating rubber of the vehicle inner carcass layer is set to 56 to 66, and the rubber hardness Ho is determined from the rubber hardness Hi. Is also increased by 3 or more.

  In the pneumatic tire of the first aspect of the present invention, the rubber hardness Ho of the type A conforming to JIS K6253 of the coat rubber of the vehicle outer carcass layer is set to 62 to 72, and the rubber hardness Hi of the coat rubber of the vehicle inner carcass layer is The rubber hardness Ho is preferably 3 or more larger than the rubber hardness Hi.

  Further, in the pneumatic tire satisfying at least one of the first and second aspects of the present invention, the thickness Go of the coat rubber of the vehicle outer carcass layer is equal to the thickness Gi of the coat rubber of the vehicle inner carcass layer. It is preferable to be the same or larger than the thickness Gi.

  In a pneumatic tire according to a third aspect of the present invention, in a pneumatic tire in which a mounting direction at the time of mounting on a vehicle is specified, a carcass layer is divided into a vehicle outer carcass layer and a vehicle inner carcass layer. The coat rubber of the vehicle inner carcass layer and the coat rubber of the vehicle inner carcass layer are made of the same rubber material, the coat rubber thickness Go of the vehicle outer carcass layer is set to 1.4 to 3.0 mm, The thickness Gi is set to 0.8 to 1.5 mm, and the thickness Go of the coat rubber is set to be 0.5 mm or more larger than the thickness Gi of the coat rubber.

  In the first to third pneumatic tires described above, the tire width direction center side end of the vehicle outer carcass layer and the tire width direction center side end of the vehicle inner carcass layer respectively extend from the tire center to the left and right of the belt layer maximum width W. It is preferable to arrange within 35% of the range. Further, the tire width direction center side end of the vehicle outer side carcass layer and the tire width direction center side end of the vehicle inner side carcass layer can be separated from each other in the tire width direction.

  Further, the present invention can be applied to a pneumatic tire having a flatness ratio of 55% or less.

  As described above, the pneumatic tire of the present invention has a structure in which the carcass layer is divided into the left and right sides of the vehicle outer carcass layer and the vehicle inner carcass layer. In the first invention, the 300% modulus Mo of the coat rubber of the vehicle outer carcass layer is 13.5 to 18.5 MPa, the 300% modulus Mi of the coating rubber of the carcass layer on the vehicle inner side is set to 11.0 to 15.5 MPa, and the former modulus Mo is set to be 1.3 MPa or more larger than the latter modulus Mi. The tire rigidity on the outside of the vehicle becomes large and the tire rigidity on the inside of the vehicle becomes small, so that both steering stability and ride comfort can be achieved.

  In the second aspect of the present invention, the rubber hardness Ho of the coat rubber of the vehicle outer carcass layer is set to 62 to 72, the rubber hardness Hi of the coat rubber of the vehicle inner carcass layer is set to 56 to 66, and the former rubber hardness Ho is set to the latter rubber. Since the hardness Hi is set to 3 or more than the hardness Hi, the tire rigidity on the outside of the vehicle is increased and the tire rigidity on the inside of the vehicle is decreased, so that both steering stability and riding comfort can be achieved.

  In the pneumatic tire of the third aspect of the present invention, the coat rubber of the vehicle outer carcass layer and the coat rubber of the vehicle inner carcass layer are made of the same rubber material, and the thickness Go of the coat rubber of the vehicle outer carcass layer is 1. 4 to 3.0 mm, coat rubber thickness Gi of the carcass layer inside the vehicle is 0.8 to 1.5 mm, and the former coat rubber thickness Go is 0.5 mm or more than the latter coat rubber thickness Gi. Since it has been increased, the tire rigidity on the outside of the vehicle is increased and the tire rigidity on the inside of the vehicle is decreased, so that it is possible to achieve both steering stability and ride comfort.

  Moreover, since any of the pneumatic tires of the first to third inventions only needs to adjust the characteristics or thickness of the coat rubber, it is possible to select and set steering stability and riding comfort in a wide range, And tire durability is not reduced.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of a pneumatic tire of the present invention.

  In FIG. 1, the pneumatic tire includes a tread portion 1, left and right sidewall portions 2, and a bead portion 3, and the vehicle outer carcass layer 6 and the vehicle inner side when the mounting direction of the carcass layer is specified when the tire is mounted on the vehicle. The carcass layer 7 is divided into left and right parts. The vehicle outer carcass layer 6 and the vehicle inner carcass layer 7 are each composed of two upper and lower layers. The outer ends in the tire width direction are folded around the left and right bead cores 4 and 4 from the tire inner side to the outer side. A belt layer 8 of two steel cords is arranged on the outer peripheral side of the vehicle outer carcass layer 6 and the vehicle inner carcass layer 7 of the tread portion 1 so that the cords cross each other, and a reinforcing cord is attached to the tire outer periphery on the outer peripheral side. A belt cover layer 9 that is spirally wound at a low angle of 0 ° to 10 ° with respect to the direction is disposed.

  In the present invention, the vehicle outer carcass layer 6 and the vehicle inner carcass layer 7 are configured such that at least one of the modulus of the coated rubber, the rubber hardness, and the thickness of the coated rubber is different from each other. As shown in FIG. 2, the vehicle outer carcass layer 6 is formed by coating a plurality of aligned carcass cords 11 with a coat rubber 12, and the vehicle inner carcass layer 7 is formed by coating the carcass cord 11 with a coat rubber 13. Composed. As shown in FIG. 1, when two carcass layers are arranged in the upper and lower layers in the tire radial direction, at least one of them may be divided into left and right parts from the vehicle outer carcass layer 6 and the vehicle inner carcass layer 7.

  In addition, the carcass cords 11 constituting the vehicle outer carcass layer 6 and the vehicle inner carcass layer 7 may be formed of the same material or different materials. However, in the case of being formed of different materials, the vehicle outer carcass layer 6 is formed. It is preferable that the rigidity is equal to or greater than that of the vehicle inner carcass layer 7.

  In the first pneumatic tire of the present invention, the 300% modulus Mo of the coat rubber 12 of the vehicle outer carcass layer 6 is 13.5 to 18.5 MPa, and the 300% modulus Mi of the coat rubber 13 of the vehicle inner carcass layer 7 is 11. While the pressure is set to 0 to 15.5 MPa, the former modulus Mo is set to be 1.3 MPa or more larger than the latter modulus Mi.

  Thus, by setting the modulus of each of the coat rubbers 12 and 13 constituting the vehicle outer carcass layer 6 and the vehicle inner carcass layer 7, the tire rigidity on the vehicle inner side is made relatively smaller than the tire rigidity on the vehicle outer side. For this reason, when the tire is mounted on a vehicle with a negative camber, the tire rigidity inside the vehicle that is mainly grounded during straight running is relatively reduced, so that deterioration in riding comfort can be suppressed. In addition, since the tire rigidity on the outside of the vehicle is relatively large at the time of lane change or turning, the steering stability can be improved. Therefore, it is possible to achieve both steering stability and ride comfort.

  In addition, since the carcass layer in which the moduli Mo and Mi of the coat rubbers 12 and 13 are respectively adjusted may be divided and arranged on the left and right, it is possible to select and set steering stability and riding comfort in a wide range, and the carcass layer Since it is not necessary to extend the folded end to the flex zone, tire durability is not impaired.

  The modulus Mo of the coat rubber 12 of the vehicle outer side carcass layer 6 is 13.5 to 18.5 MPa, preferably 14 to 16.5 MPa. If the modulus Mo is less than 13.5 MPa, the effect of increasing the tire stiffness outside the vehicle cannot be obtained, and the steering stability cannot be increased. On the other hand, if it exceeds 18.5 MPa, the tire stiffness becomes excessive and the ride comfort and ground contact properties are impaired.

  The modulus Mi of the coat rubber 13 of the vehicle inner carcass layer 7 is 11.0 to 15.5 MPa, preferably 11.5 to 14 MPa. If the modulus Mi is less than 11.0 MPa, the tire stiffness is insufficient and the steering stability cannot be maintained. On the other hand, if it exceeds 15.5 MPa, the tire rigidity on the inside of the vehicle becomes excessive and the ride comfort is reduced.

  The former modulus Mo is 1.3 MPa or more larger than the latter modulus Mi, preferably 2.0 MPa or more. When the difference Mo-Mi between the modulus Mo and the modulus Mi is less than 1.3 MPa, it is impossible to achieve both steering stability and ride comfort. In this specification, 300% modulus refers to a value measured according to JIS K6251.

  In the second pneumatic tire of the present invention, the rubber hardness Ho of the coat rubber 12 of the vehicle outer carcass layer 6 is 62 to 72, the rubber hardness Hi of the coat rubber 13 of the vehicle inner carcass layer 7 is 56 to 66, and the former. The rubber hardness Ho is made 3 or more larger than the latter rubber hardness Hi.

  Thus, by setting the rubber hardness of the coat rubbers 12 and 13 of the vehicle outer side carcass layer 6 and the vehicle inner side carcass layer 7, the tire rigidity on the vehicle outer side is relatively increased, and the tire rigidity on the vehicle inner side is relatively increased. Make it smaller. For this reason, as described above, it is possible to achieve both steering stability and ride comfort. In addition, since the carcass layer with the rubber hardness Ho and Hi adjusted for the coat rubber can be divided into left and right, the driving stability and riding comfort can be selected and set in a wide range, and the tire durability is reduced. I will not let you.

  The rubber hardness Ho of the coat rubber 12 of the vehicle outer side carcass layer 6 is 62 to 72, preferably 64 to 69. If the rubber hardness Ho is less than 62, the effect of increasing the tire stiffness outside the vehicle cannot be obtained, and the steering stability cannot be increased. On the other hand, if it exceeds 72, the tire stiffness becomes excessive and the ride comfort and ground contact are impaired.

  The rubber hardness Hi of the coat rubber 13 of the vehicle inner carcass layer 7 is 56 to 66, preferably 58 to 64. When the rubber hardness Hi is less than 56, the tire rigidity is insufficient and the steering stability cannot be maintained. On the other hand, if it exceeds 66, the tire rigidity on the inside of the vehicle becomes excessive and the ride comfort is lowered.

  The former rubber hardness Ho is 3 or more, preferably 5 or more, greater than the latter rubber hardness Hi. If the difference Ho-Hi between the rubber hardness Ho and the rubber hardness Hi is less than 3, it is impossible to achieve both steering stability and riding comfort. In the present specification, the rubber hardness is a value measured at a temperature of 20 ° C. by a durometer type A conforming to JIS K6253.

  In the first aspect of the present invention described above, the rubber hardness Ho of the coat rubber 12 constituting the vehicle outer side carcass layer 6 and the rubber hardness Hi of the coat rubber 13 constituting the vehicle inner side carcass layer 7 are respectively in the second aspect of the present invention. It is preferable that the specified rubber hardnesses Ho and Hi of the coated rubbers 12 and 13 are satisfied. As a result, it is possible to more reliably achieve both steering stability and ride comfort.

  In the pneumatic tire satisfying at least one of the first and second aspects of the present invention, the thickness Go of the coat rubber 12 constituting the vehicle outer carcass layer 6 and the thickness of the coat rubber 13 constituting the vehicle inner carcass layer 7 Although the relationship with the thickness Gi is not particularly limited, the thickness Go of the former coat rubber is preferably the same as the thickness Gi of the latter coat rubber or larger than the thickness Gi of the coat rubber. . As described above, by setting the thicknesses Go and Gi of the coat rubber, it is possible to further ensure the compatibility between the handling stability and the riding comfort. More preferably, the respective thicknesses Go and Gi of the coat rubber constituting the carcass layer satisfy the relationship between the thicknesses Go and Gi of the coat rubber defined in the third aspect of the present invention described below.

  In the third pneumatic tire of the present invention, the coat rubber 12 of the vehicle outer carcass layer 6 and the coat rubber 13 of the vehicle inner carcass layer 7 are made of the same rubber material, and the thickness Go of the coat rubber 12 is 1.4-3. The thickness Gi of the coat rubber 13 is set to 0.8 to 1.5 mm, and the thickness Go of the coat rubber 12 is set to be 0.5 mm or more larger than the thickness Gi of the coat rubber 13.

  In this way, the coat rubbers 12 and 13 of the vehicle outer carcass layer 6 and the vehicle inner carcass layer 7 are made of the same rubber material, the thicknesses Go and Gi are set, and the thickness Go of the coat rubber 12 is set to that of the coat rubber 13. By making it larger than the thickness Gi, the tire rigidity on the vehicle outer side is relatively increased and the vehicle inner side is relatively decreased. For this reason, as described above, it is possible to achieve both steering stability and ride comfort. In addition, since the carcass layer with the rubber thicknesses Go and Gi of the coat rubber adjusted respectively may be divided and arranged on the left and right, the steering stability and ride comfort can be selected and set in a wide range, and the tire durability is improved. There is no reduction.

  The thickness Go of the coat rubber 12 of the vehicle outer side carcass layer 6 is 1.4 to 3.0 mm, preferably 2.0 to 2.5 mm. If the thickness Go of the coat rubber is less than 1.4 mm, the effect of increasing the tire rigidity on the outside of the vehicle cannot be obtained, and the steering stability cannot be increased. On the other hand, if it exceeds 3.0 mm, the tire stiffness becomes excessive and the ride comfort and ground contact are impaired.

  The thickness Gi of the coat rubber 13 of the vehicle inner carcass layer 7 is 0.8 to 1.5 mm, preferably 1.0 to 1.5 mm. If the thickness Gi of the coat rubber is less than 0.8 mm, the tire rigidity is insufficient and the steering stability cannot be maintained. On the other hand, if it exceeds 1.5 mm, the tire rigidity on the inner side of the vehicle becomes excessive and the ride comfort is lowered.

  The thickness Go of the former coat rubber 12 is 0.5 mm or more larger than the thickness Gi of the latter coat rubber 13, preferably 1.0 mm or more. When the difference Go-Gi between the thickness Go of the coat rubber and the thickness Gi of the coat rubber is less than 0.5 mm, it is impossible to achieve both steering stability and ride comfort.

  In the first to third aspects of the present invention described above, the tire width direction center side end 6e of the vehicle outer side carcass layer 6 and the tire width direction center side end 7e of the vehicle inner side carcass layer 7 are respectively tires as shown in FIG. It is preferable to arrange the belt layer 8 within a range of 35% of the maximum width W of the belt layer 8 from the center CL to the left and right. When the center side ends 6e and 7e in the tire width direction of the carcass layers 6 and 7 are located outside the range of ± 35% of the belt layer maximum width W from the tire center CL, the center side ends 6e and 6e of each carcass layer 7e easily interferes with the edge of the cap rubber of the tread portion 1 and may cause a failure.

  Moreover, the tire width direction center side end 6e of the vehicle outer side carcass layer 6 and the tire width direction center side end 7e of the vehicle inner side carcass layer 7 may be disposed adjacent to each other as shown in FIG. Alternatively, the center side end 6e of the vehicle outer side carcass layer 6 and the center side end 7e of the vehicle inner side carcass layer 7 can be arranged so as to be separated from each other in the tire width direction. By arranging the tire width direction center side ends 6e and 7e of the carcass layer at intervals in the tire width direction, the pneumatic tire of the present invention can be easily manufactured.

  The tire of the present invention can be applied regardless of the tire size, but is particularly suitable for producing a pneumatic tire having a flatness ratio of 55% or less. In such a tire having a flatness ratio, steering stability is regarded as important. However, by applying the tire configuration of the present invention, it is possible to improve riding comfort and achieve compatibility with steering stability. In the present invention, the flatness of the pneumatic tire is based on JATMA regulations.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to these Examples.

Examples 1 and 2
The pneumatic tire having a tire size of 245 / 45R18 and having the tire structure of FIG. 1 is configured such that the carcass layer is divided into a vehicle outer carcass layer and a vehicle inner carcass layer, and the rubber hardness Ho and Hi of each coat rubber and the coat rubber Three types of pneumatic tires (Examples 1 and 2 and Comparative Example 1) in which the thicknesses Go and Gi are set to be the same, and 300% modulus Mo and Mi of each coated rubber are set as shown in Table 1. ).

  About the obtained three types of pneumatic tires, the direction at the time of mounting on the vehicle is designated and mounted on the vehicle, and the steering stability and riding comfort are evaluated by the following methods, respectively, and the results are shown in Table 1.

[Steering stability]
The obtained pneumatic tire is assembled on a rim of 17 x 8 JJ, mounted on an imported vehicle with a displacement of 2.5 liters according to the determined mounting direction, and a skilled test driver under the condition of an air pressure of 220 kPa However, sensory evaluation of steering stability during straight running and lane change was performed. The evaluation result is a relative evaluation (minimum 0.5 to maximum 5.0) with Comparative Example 1 being 3.0, and the greater this score is, the better the steering stability is.

[Ride comfort]
The resulting pneumatic tire is assembled on a rim of 17 x 8 JJ, mounted on an imported vehicle with a displacement of 2.5 liters according to the determined mounting direction, and a test with irregularities under the condition of an air pressure of 220 kPa. The actual vehicle was run at 50 km / h, and sensitivity evaluation was conducted by three specialized panelists. The evaluation result is a relative evaluation (minimum 0.5 to maximum 5.0) with Comparative Example 1 being 3.0, and the higher this score is, the better the riding comfort is.

Examples 3 and 4
A pneumatic tire having a tire size of 245 / 45R18 and having the tire structure of FIG. 1 has a carcass layer divided into a vehicle outer carcass layer and a vehicle inner carcass layer, and 300% modulus Mo and Mi of the respective coated rubbers and coated rubbers. The three types of pneumatic tires (Examples 3 and 4 and Comparative Example 1) were set under the common condition that the thicknesses Go and Gi of the tires were the same, and the rubber hardnesses Ho and Hi of the respective coated rubbers were set as shown in Table 2. ).

  About the obtained three types of pneumatic tires, the direction at the time of mounting on the vehicle is designated and mounted on the vehicle, and the steering stability and riding comfort are evaluated by the above methods, respectively, and the results are shown in Table 2.

Examples 5 and 6
A pneumatic tire having a tire size of 245 / 45R18 and having the tire structure of FIG. 1 is configured such that the carcass layer is divided into a vehicle outer carcass layer and a vehicle inner carcass layer, and each coat rubber is made of the same rubber material. Were used, and three types of pneumatic tires (Examples 5 and 6 and Comparative Example 1) in which the thicknesses Go and Gi of the respective coated rubbers were set as shown in Table 3 were manufactured.

  About the obtained three types of pneumatic tires, the direction at the time of mounting on the vehicle is designated and mounted on the vehicle, and the steering stability and the riding comfort are evaluated by the above methods, respectively, and the results are shown in Table 3.

Examples 7-9
A pneumatic tire having a tire size of 245 / 45R18 and having the tire structure of FIG. 1 has a carcass layer divided into a vehicle outer carcass layer and a vehicle inner carcass layer, and 300% modulus Mo, Mi, rubber of each coat rubber Seven types of pneumatic tires (Examples 7 to 9, Comparative Examples 1 and 4 to 6) having hardness Ho and Hi and coat rubber thicknesses Go and Gi set as shown in Table 4 were manufactured.

  About the obtained seven types of pneumatic tires, the direction at the time of mounting on the vehicle is designated and mounted on the vehicle, and the steering stability and the riding comfort are evaluated by the above methods, respectively, and the results are shown in Table 4.

It is meridian direction sectional drawing which shows an example of the pneumatic tire which consists of embodiment of this invention. It is explanatory drawing which shows typically an example of a structure of the carcass layer used by this invention.

Explanation of symbols

6 Vehicle outer side carcass layer 6e Tire width direction center side end 7 Vehicle inner side carcass layer 7e Tire width direction center side end 11 Carcass cord 12, 13 Coat rubber CL Tire center line

Claims (8)

For pneumatic tires with the specified mounting direction when the vehicle is mounted,
The carcass layer is divided into a vehicle outer carcass layer and a vehicle inner carcass layer, and the 300% modulus Mo of the coating rubber of the vehicle outer carcass layer is set to 13.5 to 18.5 MPa. A pneumatic tire having a 300% modulus Mi of 11.0 to 15.5 MPa and a modulus Mo that is 1.3 MPa or more larger than the modulus Mi. For pneumatic tires with the specified mounting direction when the vehicle is mounted,
The carcass layer is divided into a vehicle outer carcass layer and a vehicle inner carcass layer on the left and right sides, and the type A rubber hardness Ho conforming to JIS K6253 of the coat rubber of the vehicle outer carcass layer is set to 62 to 72. A pneumatic tire in which the rubber hardness Hi of the coated rubber is 56 to 66 and the rubber hardness Ho is 3 or more larger than the rubber hardness Hi.   The rubber hardness Ho of the type A conforming to JIS K6253 of the outer rubber carcass layer is 62 to 72, the rubber hardness Hi of the outer rubber carcass layer is 56 to 66, and the rubber hardness Ho is The pneumatic tire according to claim 1, wherein the pneumatic tire is 3 or more larger than the rubber hardness Hi.   The pneumatic tire according to claim 1, 2, or 3, wherein a thickness Go of the coat rubber of the vehicle outer carcass layer is equal to or greater than a thickness Gi of the coat rubber of the vehicle inner carcass layer. For pneumatic tires with the specified mounting direction when the vehicle is mounted,
The carcass layer is divided into a vehicle outer carcass layer and a vehicle inner carcass layer on the left and right sides, and the vehicle outer carcass layer coat rubber and the vehicle inner carcass layer coat rubber are made of the same rubber material. The coating rubber thickness Go is set to 1.4 to 3.0 mm, the coating rubber thickness Gi of the vehicle inner carcass layer is set to 0.8 to 1.5 mm, and the coating rubber thickness Go is set to the thickness of the coating rubber. Pneumatic tire larger than Gi by 0.5 mm or more.   The tire width direction center side end of the vehicle outer side carcass layer and the tire width direction center side end of the vehicle inner side carcass layer are respectively disposed within a range of 35% of the belt layer maximum width W from the tire center to the left and right. The pneumatic tire according to any one of 5.   The pneumatic tire according to claim 6, wherein a tire width direction center side end of the vehicle outer side carcass layer and a tire width direction center side end of the vehicle inner side carcass layer are separated from each other in the tire width direction.   The pneumatic tire according to any one of claims 1 to 7, wherein the tire has a flatness ratio of 55% or less.