JP6294791B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having excellent uneven wear resistance and wear resistance.

  A pneumatic tire is required to improve uneven wear resistance and wear resistance. The following Patent Document 1 discloses that the uneven wear resistance performance is improved by suppressing the slippage of the tread rubber at the shoulder portion by optimizing the contact length in the tire circumferential direction of the shoulder portion near the tread end. doing.

  However, there is a need for a pneumatic tire having even better uneven wear resistance and wear resistance.

Japanese Patent Application Laid-Open No. 09-309301 Special table 2002-544045 gazette Japanese Patent Laid-Open No. 10-100633 International Publication No. 2008/099899

  The main object of the present invention is to provide a pneumatic tire having excellent uneven wear resistance and wear resistance by improving the carcass profile.

The present invention relates to a carcass that extends from a tread portion to a bead core of a bead portion through a sidewall portion, and a belt layer that includes at least two belt plies arranged on the outer side in the tire radial direction of the carcass and on the inner side of the tread portion. The belt layer includes an inner belt ply in contact with the carcass and an outer belt ply disposed on the outer side in the tire radial direction of the inner belt ply, and is attached to a normal rim and has a normal internal pressure. In the meridional section of the tire including the tire rotation axis in a normal state in which no load is filled, the carcass profile that is the profile of the carcass ply satisfies the relationships of the following formulas (1) to (4).
(R2 / R1) = − 67.213 × (L1 / L2) ³ + 143.38 × (L1 / L2) ² −103.36 × (L1 / L2) + A (1)
0.16 ≦ (R2 / R1) ≦ 0.34 (2)
0.60 ≦ (L1 / L2) ≦ 0.67 (3)
25.2 ≦ A ≦ 25.3 (4)
R1 is a straight line connecting the inner end point that is the tire equator position of the carcass profile, the outer point of the carcass profile formed at the same tire axial direction position as the outer end of the outer belt ply in the tire axial direction, and the inner end point. The maximum separation point of the carcass profile where the carcass profile and the straight line are the maximum distance in the tire radial direction, and the inner middle point of the carcass profile that is an intermediate position in the tire axial direction between the maximum separation point and the inner end point The radius of curvature of the inner arc passing through the three points.
R2 is a radius of curvature of an outer arc passing through the three points of the maximum separation point, the outer middle point of the carcass profile that is an intermediate position in the tire axial direction between the maximum separation point and the outer point, and the outer point. is there.
L1 is the distance in the tire axial direction from the inner end point to the maximum separation point.
L2 is the distance in the tire axial direction from the inner end point to the outer point.

  In the pneumatic tire according to the present invention, the distance in the tire radial direction between the 40% point and the inner end point at a position where the carcass profile is 40% of the tire axial width PW of the outer belt ply from the tire equator is It is desirable that it is 1.95% or less of the tire ply width PW of the belt ply.

  In the pneumatic tire according to the present invention, the tread portion includes a band layer made of at least one full band ply covering the entire width of the belt layer on the outer side in the tire radial direction of the belt layer to form the belt ply. The belt cord is preferably inclined at an angle of 24 to 30 ° with respect to the tire equator.

The pneumatic tire of the present invention has a carcass ply profile, which is a carcass ply profile, in a tire meridional section including a tire rotating shaft in a normal state in which a normal rim is mounted and a normal internal pressure is filled with a normal internal pressure. The relations 1) to (4) are satisfied.
(R2 / R1) = − 67.213 × (L1 / L2) ³ + 143.38 × (L1 / L2) ² −103.36 × (L1 / L2) + A (1)
0.16 ≦ (R2 / R1) ≦ 0.34 (2)
0.60 ≦ (L1 / L2) ≦ 0.67 (3)
25.2 ≦ A ≦ 25.3 (4)

R1 is a straight line connecting the inner end point, which is the tire equator position of the carcass profile, and the outer point and inner end point of the carcass profile formed at the same tire axial position as the outer end of the outer belt ply in the tire axial direction. The carcass profile has a maximum separation point where the profile and the straight line have a maximum distance in the tire radial direction, and an inner middle point of the carcass profile which is an intermediate position in the tire axial direction between the maximum separation point and the inner end point. The radius of curvature of the inner arc.
R2 is the radius of curvature of the outer arc passing through the three points of the maximum separation point, the outer middle point of the carcass profile that is an intermediate position in the tire axial direction between the maximum separation point and the outer point, and the outer point.
L1 is the distance in the tire axial direction from the inner end point to the maximum separation point.
L2 is the distance in the tire axial direction from the inner end point to the outer point.

  In such a pneumatic tire, a normal load is applied to a pneumatic tire in a normal state, and the profile of the carcass is optimized in a normal load state when the tire is grounded on a flat surface with a camber angle of 0 °. The ground pressure is distributed in a balanced manner between the tread ends. For this reason, since the slip of the tread rubber becomes uniform in the pneumatic tire of the present invention, uneven wear resistance and wear resistance are greatly improved. Further, the pneumatic tire of the present invention has little change with time, and the shape of the carcass profile at the initial stage of tire manufacture is maintained until the end of use of the tire. For this reason, the above-mentioned effect is exhibited over a long period of time.

It is sectional drawing which shows the right half of the tire of the normal state of one Embodiment of this invention. It is a figure explaining the profile of the carcass ply and belt ply of FIG. It is a graph explaining the area | region of Formula (1)-(4). It is a schematic diagram of the carcass profile of the normal state of an Example and a comparative example. It is sectional drawing of the belt ply of this embodiment in a normal load application state. (A) is sectional drawing of the belt ply of the comparative example in a normal load load state, (b) is sectional drawing of the belt ply of the other comparative example in a normal load load state.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross section of a tire meridian in a normal state of a pneumatic tire (hereinafter, simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment can be suitably used as, for example, a tire for a passenger car.

  The “normal state” is a no-load state in which a tire is assembled on a normal rim (not shown) and filled with a normal internal pressure. In this specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in this normal state.

  The “regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA. For ETRTO, "Measuring Rim". In addition, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based, and is “maximum air pressure” for JATMA, and “TIRE” for TRA. The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO. When the tire is for a passenger car, the normal internal pressure is 180 kPa.

  The tire 1 of the present embodiment includes a tread rubber 2G having a tread surface 2a that contacts the road surface, and sidewall rubber 3G disposed on both sides of the tread rubber 2G in the tire axial direction.

  It is desirable that the tread rubber 2G has a thickness t in the tire radial direction that is substantially constant over the tire axial direction or gradually decreases toward the outer side in the tire axial direction. Such a tire 1 is suitable for making the contact pressure uniform. The tread rubber 2G of the present embodiment has a thickness t that gradually decreases outward in the tire axial direction. In order to exhibit the above-described action more effectively, the tread rubber 2G desirably has a thickness t1 at the tread end Te that is 70% to 80% of the thickness t2 at the tire equator C.

  The “tread end Te” is defined as a contact position on the outermost side in the tire axial direction in a normal load state in which a normal load is applied to the tire 1 in a normal state and grounded on a plane with a camber angle of 0 degree. Further, in the normal state, the distance in the tire axial direction between the tread ends Te and Te is determined as the tread ground contact width TW.

  “Regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is specified for JATMA, and the table “TIRE LOAD LIMITS AT for TRA” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO. When the tire is for a passenger car, the normal load is a load corresponding to 88% of the load.

  The tire 1 of the present embodiment includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt disposed on the outer side in the tire radial direction of the carcass 6 and on the inner side of the tread rubber 2G. A layer 7 and a band layer 9 disposed outside the belt layer 7 in the tire radial direction are configured.

  The carcass 6 includes a main body portion 6a straddling the pair of bead cores 5 and 5 in a toroidal shape, and a folded portion 6b that is continuous on both sides of the main body portion 6a and is folded around the bead core 5 from the inner side to the outer side in the tire axial direction. It is composed of at least one carcass ply 6A in the present embodiment. In the carcass ply 6A, carcass cords made of, for example, organic fibers are arranged at an angle of, for example, 75 to 90 ° with respect to the tire equator C. A bead apex rubber 8 extending in a taper shape on the outer side in the tire radial direction of the bead core 5 is disposed between the main body portion 6a and the folded portion 6b.

  The belt layer 7 is composed of at least two belt plies 7A and 7B, in the present embodiment, in the tire radial direction, and in the outer two. In the present embodiment, the inner belt ply 7A is in contact with the carcass 6. The outer belt ply 7B is disposed on the outer side in the tire radial direction of the inner belt ply 7A. The belt plies 7A and 7B of the present embodiment are provided with the width center at the tire equator C.

  The inner belt ply 7A of the present embodiment is formed as a belt ply having a larger width in the tire axial direction than the outer belt ply 7B.

  In order to increase the rigidity of the tread portion 2, it is desirable that the tire axial width PW of the outer belt ply 7B is, for example, about 90% to 110% of the tread ground contact width TW. In the present embodiment, the outer end 7Be of the outer belt ply 7B is disposed on the outer side in the tire axial direction than the tread end Te.

  Each of the belt plies 7A and 7B preferably has a belt cord (not shown) made of steel that is inclined with respect to the tire equator C within an angle range of, for example, 24 to 30 °. When the angle of the belt cord exceeds 30 degrees, the curvature radius Ra of the center region Ch in the vicinity of the tire equator C of the tread surface 2a becomes excessively small, and the wear resistance performance of the center region Ch may be deteriorated. When the angle of the belt cord is less than 24 degrees, the curvature radius Rb of the shoulder region Sh near the tread end Te of the tread surface 2a becomes excessively small, and the wear resistance performance of the shoulder region Sh may be deteriorated. The belt plies 7A and 7B are overlapped so that the belt cords intersect each other.

  The band layer 9 is formed of at least one full band ply that covers the entire width of the belt layer 7, in this embodiment, one full band ply. The band layer 9 of this embodiment is terminated on the outer side in the tire axial direction from the outer end 7Ae of the inner belt ply 7A. The tire 1 of the present embodiment is, for example, grounded over the tire axial direction of the tread portion 2 as compared to a tire of a so-called edge band ply (not shown) that covers only the shoulder region Sh of the inner belt ply 7A. Since the pressure can be equalized, uneven wear resistance is improved.

  The band layer 9 has a band cord (not shown) arranged with respect to the tire equator C at an angle of, for example, 5 degrees or less, more preferably 3 degrees or less. The band cord is preferably an organic fiber cord such as nylon, rayon, polyester, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), aromatic polyamide, or polyparaphenylene benzobisoxazole (PBO).

  The tire 1 of the present embodiment further includes a cushion rubber 10 having a substantially triangular cross section that fills a gap between the belt layer 7 and the carcass 6.

  The cushion rubber 10 increases the rigidity of the buttress portion B between the tread end Te and the sidewall portion 3, suppresses the deformation amount of the buttress portion B at the time of ground contact, and suppresses the slip of the tread rubber 2 </ b> G. For this reason, abrasion resistance performance etc. can improve further.

FIG. 2 is a view for explaining profiles in a normal state of the carcass ply 6A and the outer belt ply 7B. As shown in FIG. 2, in the pneumatic tire 1 of the present invention, the carcass profile Kp that is the profile of the carcass ply 6A satisfies the following expressions (1) to (4).
(R2 / R1) = − 67.213 × (L1 / L2) ³ + 143.38 × (L1 / L2) ² −103.36 × (L1 / L2) + A (1)
0.16 ≦ (R2 / R1) ≦ 0.34 (2)
0.60 ≦ (L1 / L2) ≦ 0.67 (3)
25.2 ≦ A ≦ 25.3 (4)

Here, R1, R2, L1, and L2 are as follows.
R1 includes an inner end point 11 which is a tire equator position of the carcass profile Kp, and an outer point 12 and an inner end point 11 of the carcass profile Kp formed at the same tire axial direction position as the outer axial end 7Be of the outer belt ply 7B. The carcass profile Kp and the straight line n are connected by a straight line n, and the carcass profile Kp has a maximum separation point 13 in the radial direction of the tire, and an intermediate position in the tire axial direction between the maximum separation point 13 and the inner end point 11. This is the radius of curvature of the inner circular arc 15 passing through three points of the inner middle point 14 of a certain carcass profile Kp.
R2 is the curvature of the maximum arcing point 13, the outer midpoint 16 of the carcass profile Kp, which is an intermediate position in the tire axial direction between the maximum spacing point 13 and the outer point 12, and the outer arc 17 passing through the three points of the outer point 12. Radius.
L1 is the distance in the tire axial direction from the inner end point 11 to the maximum separation point 13.
L2 is the distance in the tire axial direction from the inner end point 11 to the outer point 12.

  Further, in this specification, each point of the carcass profile Kp is located on the ply center line 6c of the carcass ply 6A in the tire meridian cross section as shown in FIG.

  In the tire 1, the largest ground pressure acts on the tread surface 2 a on the maximum separation point 13. For this reason, the above formulas (1) to (1) relating to the ratio (R2 / R1) of the radius of curvature R1 of the inner arc 15 and the radius of curvature R2 of the outer arc 17 and the position (L1 / L2) of the maximum separation point 13 in the tire axial direction. In the tire 1 that satisfies (4), since the carcass profile Kp is optimized in the normal load state, the ground pressure is distributed between the tread ends Te and Te in a well-balanced manner. Thereby, since the slip of the tread rubber 2G becomes uniform, uneven wear resistance and wear resistance are improved. Further, the tire 1 satisfying the expressions (1) to (4) has a small change with time due to the optimization of the carcass profile Kp, and the shape of the carcass profile Kp at the initial stage of manufacture is maintained until the end of use of the tire. Thereby, the above-mentioned effect is exhibited over a long period of time. Therefore, the pneumatic tire 1 of the present invention can exhibit excellent uneven wear resistance and wear resistance. The reasoning for such action is detailed below.

  In FIG. 3, the horizontal axis is the ratio of the distances (L1 / L2), and the vertical axis is the ratio of the curvature radii of the inner arc 15 and the outer arc 17 (R2 / R1). It is a graph which shows the area | region E which satisfies. The carcass profile Kp1 of the tire 1 that satisfies the expressions (1) to (4), for example, constituting the X1 point (L1 / L2) = 0.64, (R2 / R1) = 0.21) in FIG. This is shown in FIG. In FIG. 4, the vertical axis represents the height in the tire radial direction from the outer point 12 of the carcass profile Kp, and the horizontal axis represents the ratio of the distance in the tire axial direction from the inner end point 11 of the carcass profile Kp.

  FIG. 5 is a cross-sectional view including the belt plies 7A and 7B in a normal load applied state of the tire 1 having the carcass profile Kp1. As shown in FIG. 5, in the tire constituting the point X1, according to the shape of the carcass profile Kp1, the inner and outer belt plies 7A and 7B smoothly extend outward in the tire radial direction toward the outer side in the tire axial direction. Deform. Thereby, a relatively larger ground pressure than the tire equator C acts on the shoulder region Sh where heel and toe wear is likely to occur by the inner and outer belt plies 7A and 7B. That is, since the contact pressure is distributed in a well-balanced manner between the tread ends Te, Te, the slip is made uniform. For this reason, wear resistance performance and uneven wear resistance performance are improved. Further, in a tire in which the contact pressure acts in a well-balanced manner, vibration due to a rigidity step is suppressed, so that a change with time of the carcass profile Kp is reduced, and the shape is maintained until the end of use of the tire. In the present invention, by improving the carcass profile Kp in the normal state, the shape of the belt plies 7A and 7B in the normal load applied state close to the actual running state can be optimized, so the wear resistance performance and the like are improved. can do.

  In addition, in the tire 1 that satisfies only the formula (1) and the formula (4), the wear resistance performance and the partial wear resistance performance may not be improved. As shown in FIG. 3, as a tire 1 that satisfies the expressions (1) and (4) and does not satisfy the expressions (2) and (3), for example, a Y1 point ((L1 / L2) = 0.70, (R2 / R1) = 0.08)) or Y2 points ((L1 / L2) = 0.52, (R2 / R1) = 0.77)).

  FIG. 4 further shows the shapes of the carcass profiles Kp2 and Kp3 of the tire constituted by the points Y1 and Y2. 6A is a cross-sectional view including the belt plies 7A and 7B in a normal load state of the tire 1 having the carcass profile Kp2, and FIG. 6B is a normal load of the tire 1 having the carcass profile Kp3. It is sectional drawing containing belt ply 7A and 7B in a load state. As shown in FIG. 4, the carcass profile Kp2 constituted by the points Y1 has a maximum separation point 13 disposed relatively outside in the tire axial direction, and the radius of curvature R2 of the outer arc 17 is equal to the inner arc 15. The radius of curvature R1 is relatively large. In such a tire, as shown in FIG. 6 (a), the inner belt ply 7A and the outer belt ply 7B are greatly inclined so as to spring up toward the road surface side toward the outer side in the tire axial direction in the shoulder region Sh. Yes. For this reason, an excessively large ground pressure acts on the shoulder region Sh by the belt plies 7A and 7B on the tire constituting the Y1 point, so that the wear resistance performance and uneven wear resistance performance in the shoulder region Sh deteriorate. .

  Further, as shown in FIG. 4, the tire constituted by the Y2 point has the maximum separation point 13 arranged on the inner side in the tire axial direction and the ratio of the curvature radii ( R2 / R1) increases. In such a tire, as shown in FIG. 6B, each belt ply 7A, 7B extends from the tire equator C outward in the tire axial direction substantially parallel to the road surface. For this reason, in the tire 1 constituting the Y2 point, the contact pressure in the shoulder region Sh becomes smaller than that of the tire constituted by the Y1 point, and the wear resistance performance and the like in the shoulder region Sh are improved. On the other hand, in the tire 1 constituting the Y2 point, a larger ground pressure acts on the tire equator C side relatively than the tire constituted by the Y1 point. Therefore, the tire 1 constituted by the Y2 point also does not act in a balanced manner over the tire axial direction, and the wear resistance performance and uneven wear resistance performance in the center region Ch deteriorate.

  As described above, even when the above expressions (1) and (4) are satisfied, the uneven wear resistance performance is deteriorated in the tire in which the carcass profile Kp constitutes the Y1 point and the Y2 point. For this reason, the inventors further experimented to optimize the carcass profile Kp by defining the equations (2) and (3), and in the normal load application state, the ground contact pressure over the tire axial direction. By arranging in a well-balanced manner, tires with excellent wear resistance and other properties were derived.

  When the ratio (R2 / R1) between the curvature radius R1 of the inner arc 15 and the curvature radius R2 of the outer arc 17 is large, the belt plies 7A and 7B cannot be effectively deformed, and the contact pressure in the shoulder region Sh is reduced. May become excessively small. When the ratio (R2 / R1) is small, the contact pressure at the maximum separation point 13 may be excessively high. For this reason, the ratio (R2 / R1) is preferably 0.17 to 0.25.

  When the ratio (L1 / L2) between the distance L1 in the tire axial direction from the inner end point 11 to the maximum separation point 13 and the distance L2 in the tire axial direction from the inner end point 11 to the outer point 12 is large, the ground contact in the shoulder region Sh The pressure may become excessively large. When the ratio (L1 / L2) is small, the contact pressure on the tire equator C side may be excessively increased. For this reason, the ratio (L1 / L2) is preferably 0.62 to 0.65.

  Further, as shown in FIG. 2, the carcass profile Kp is a distance in the tire radial direction between the inner end point 11 and the 40% point 18 at a position 40% of the tire axial width PW of the outer belt ply 7B from the tire equator C. It is desirable that H is 1.95% or less of the tire axial width PW of the outer belt ply 7B. If the distance H is increased, the load deformation of the entire tread portion 2 is increased, and the contact length is also increased. Therefore, the slip resistance is increased, so that the wear resistance performance may be deteriorated. If the distance H is less than 1% of the tire axial width PW of the outer belt ply 7B, the contact pressure in the shoulder region Sh may increase.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.

In order to confirm the effect of the present invention, a pneumatic tire for a passenger car of size 245 / 45R18 having the basic structure of FIG. 1 was prototyped based on the specifications of Table 1 and tested for wear resistance and uneven wear resistance. . The tread pattern is the same. The parameters other than those shown in Table 1 are substantially common. The main common specifications are as follows.
Tread contact width TW: 180mm
Number of carcass plies: 1 Carcass cord material: Polyester Carcass cord angle: 88 ° (against tire equator)
Number of belt plies: 2 Belt cord material: Steel Belt cord angle: + 28 °, -28 ° (to tire equator)
Outer belt ply tire axial width PW: 186mm
In addition, each dimension of the carcass profile of each sample tire shown in Table 1 is a measurement value measured by CT scanning in a normal state with the rim assembled on the following rim.
Rims: 18x7.5J
The test method is as follows.

<Abrasion resistance and uneven wear resistance>
Each sample tire was mounted on all wheels of a 2000cc rear-wheel drive vehicle under the following conditions, and the driver ran the vehicle on a dry asphalt test course. Thereafter, with regard to the wear resistance performance, the amount of wear at 24 locations on the center region side and 24 locations on the shoulder region side was measured for each tire. The result is shown as an index with the reciprocal of the average value of the wear amount of Example 1 as 10 points. The larger the value, the better. Regarding uneven wear resistance, the difference in wear amount between the front end and the rear end in the rotational direction was measured at eight locations on the shoulder region side block for each tire. The result is shown as an index with the reciprocal of the average value of the difference in wear amount of Example 1 as 10 points. The larger the value, the better.
Internal pressure: 230kPa
Rims: 18x7.5J
Travel distance: 10000km (50% high speed travel, 25% general travel and 25% mountain travel)
The test results are shown in Table 1.

  As a result of the test, it can be understood that the tire of the example is superior in wear resistance performance and uneven wear resistance performance as compared with the comparative example. In tests using tires with different band structures, full-band tires were superior to edge-only tires or edge-band and full-band tires. . Further, in a test using tires having different belt cord angles, those having a belt cord angle of 24 to 30 degrees were excellent in wear resistance performance and uneven wear resistance performance. In addition, a tire having a tire radial distance between the 40% point and the inner end point of the carcass profile of 1.0% to 1.95% is more resistant to wear than a tire less than 1.0% or more than 1.95%. Excellent performance and uneven wear resistance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer Kp Carcass profile

Claims (3)

A pneumatic tire including a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a belt layer made of a belt ply disposed outside the carcass in the tire radial direction and inside the tread portion. ,
The belt layer includes an inner belt ply in contact with the carcass, and an outer belt ply disposed on the outer side in the tire radial direction of the inner belt ply,
The carcass profile, which is the profile of the carcass ply in the tire meridional section including the tire rotating shaft in the normal state that is mounted on the normal rim and filled with the normal internal pressure, is a relationship of the following formulas (1) to (4): A pneumatic tire characterized by satisfying
(R2 / R1) = − 67.213 × (L1 / L2) ³ + 143.38 × (L1 / L2) ² −103.36 × (L1 / L2) + A (1)
0.16 ≦ (R2 / R1) ≦ 0.34 (2)
0.60 ≦ (L1 / L2) ≦ 0.67 (3)
25.2 ≦ A ≦ 25.3 (4)
Here, R1, R2, L1, and L2 are as follows.
R1: An inner end point that is a tire equator position of a carcass profile, an outer point of a carcass profile that is formed at the same position in the tire axial direction as an outer end in the tire axial direction of the outer belt ply, and the inner end point are connected by a straight line. A maximum separation point of the carcass profile where the profile and the straight line have a maximum distance in the tire radial direction, and an inner middle point of the carcass profile that is an intermediate position in the tire axial direction between the maximum separation point and the inner end point. Radius of curvature of inner arc passing through three points R2: three points of the maximum separation point, the outer midpoint of the carcass profile that is an intermediate position in the tire axial direction between the maximum separation point and the outer point, and the outer point Radius of curvature of outer arc passing through L1: Distance in the tire axial direction from the inner end point to the maximum separation point L2: From the inner end point to the outer point Distance of the tire axial direction   In the carcass profile, the distance in the tire radial direction between the 40% point and the inner end point at a position 40% of the tire axial width PW of the outer belt ply from the tire equator is equal to the tire axial width PW of the outer belt ply. The pneumatic tire according to claim 1, which is 1.95% or less. The tread portion includes a band layer made of at least one full band ply covering the entire width of the belt layer on the outer side in the tire radial direction of the belt layer,
The pneumatic tire according to claim 1 or 2, wherein the belt cord forming the belt ply is inclined at an angle of 24 to 30 degrees with respect to the tire equator.

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