JP6891498B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire in which a belt layer is embedded in the tread portion, and more specifically, to a pneumatic tire capable of improving durability while suppressing uneven wear in the shoulder region of the tread portion. ..

Pneumatic tires generally include a carcass layer mounted between a pair of bead portions, a plurality of belt layers arranged on the tire radial outer side of the carcass layer in the tread portion, and a tire radial outer side of the belt layer. It is provided with at least one belt reinforcing layer arranged so as to cover the belt layer, the belt layer includes a plurality of belt cords inclined with respect to the tire circumferential direction, and the belt cords intersect each other between the layers. It has a structure arranged so as to.

In recent years, there has been a strong demand for reducing rolling resistance of pneumatic tires for passenger cars, and in order to meet such demands, the tires should be designed so that the ground contact shape of the tread portion is approximately rectangular. Is being done. However, as a demerit when a rectangular ground contact shape is adopted, uneven wear tends to occur easily in the shoulder region of the tread portion. On the other hand, in order to suppress uneven wear in the shoulder region, the inclination angle of the belt cord constituting the belt layer with respect to the tire circumferential direction is made different according to the position in the tire width direction, so that the end portion of the belt layer is formed. It has been proposed to increase the rigidity in the tire circumferential direction in (see, for example, Patent Document 1).

However, in a portion where the change in the inclination angle of the belt cord is large, the distortion generated when the tire is running becomes large, and the distortion becomes a factor of deteriorating the durability. Therefore, when trying to suppress uneven wear in the shoulder region based on the setting of the inclination angle of the belt cord, it is necessary to improve the durability.

Japanese Unexamined Patent Publication No. 2011-230538

An object of the present invention is to provide a pneumatic tire capable of improving durability while suppressing uneven wear in a shoulder region of a tread portion.

The pneumatic tire of the present invention for achieving the above object includes a carcass layer mounted between a pair of bead portions, a two-layer belt layer arranged outside the carcass layer in the tread portion in the tire radial direction, and the like. The belt layer includes at least one belt reinforcing layer arranged outside in the tire radial direction, the belt layer includes a plurality of belt cords inclined with respect to the tire circumferential direction, and the belt cords intersect each other between the layers. In pneumatic tires arranged to
In at least one of the belt layers, the inclination angle α of the belt cord with respect to the tire circumferential direction at the tire center position and the inclination angle β of the belt cord with respect to the tire circumferential direction at the belt terminal position are 15 ° ≦ β <α. Satisfying the relationship of ≤35 °,
The belt layer includes a high angle region on the center side in which the inclination angle of the belt cord is in the range of α ± 1 ° and a low angle region on the shoulder side in which the inclination angle of the belt cord is in the range of β ± 1 °. The belt cord has a connecting region in which the angle of the belt cord gradually changes between the high angle region and the low angle region.
The belt reinforcing layer is arranged so as to cover at least the high angle region and the connecting region of the belt layer, and the rigidity in the tire circumferential direction per unit width is higher than that of the first region corresponding to the high angle region. It is characterized in that it is set to be low in the second region corresponding to the connecting region.

In the present invention, the tread portion is formed by adopting a structure in which the inclination angle β at the belt terminal position of the belt cord is smaller than the inclination angle α at the tire center position of the belt cord in at least one of the belt layers. Uneven wear in the shoulder area of the tire can be suppressed. However, in this case, the distortion generated during tire running becomes large in the portion where the change in the inclination angle of the belt cord becomes large, and the distortion becomes a factor of deteriorating the durability.

In view of such a situation, in the present invention, in the belt layer, a high angle region on the center side where the inclination angle of the belt cord is in the range of α ± 1 ° and a range in which the inclination angle of the belt cord is β ± 1 °. While forming a low-angle region on the shoulder side and a connecting region in which the angle of the belt cord gradually changes between these high-angle regions and the low-angle region, at least the high-angle region and the connecting region of the belt layer are formed. By arranging a belt reinforcing layer so as to cover the above, and lowering the rigidity in the tire circumferential direction per unit width in the second region corresponding to the connecting region than in the first region corresponding to the high angle region, when the tire is running. It is possible to alleviate the distortion generated around the connecting region of the belt layer and improve the durability. This makes it possible to improve durability while suppressing uneven wear in the shoulder region of the tread portion.

In the present invention, the rigidity G (kN / mm) in the tire circumferential direction per unit width of the belt reinforcing layer is such that the cross-sectional area of the band cord constituting the belt reinforcing layer is S (mm ² ) and the elastic modulus of the band cord is set. E (kN / mm ² ), the number of band cords driven in the corresponding area is N (lines), the inclination angle of the band cord with respect to the tire circumferential direction is θ (°), and the width of the corresponding area is W (mm). ), It is calculated by G = S × E × N × cos ^{4 θ / W.} The elastic modulus E is the initial tensile resistance measured according to JIS-L1017.

The rigidity of the belt reinforcing layer in the first region is calculated based on the above relational expression with respect to the total width L of each belt layer in the range of L × 2/5 centered on the tire center position. On the other hand, the rigidity of the belt reinforcing layer in the second region is in the range of 10 mm on both sides in the tire width direction around the point X where the inclination angle γ (°) of the belt cord with respect to the tire circumferential direction is (α + β) / 2. The rigidity is calculated based on the above relational expression. Further, when the point X of the belt cord of the two belt layers is deviated in the tire width direction, the midpoint position in the tire width direction of both is set as the point X', and the first belt reinforcing layer is based on this point X'. Two areas shall be specified.

In the present invention, the difference between the tilt angle α and the tilt angle β is preferably 3 ° or more. As a result, the effect of suppressing uneven wear in the shoulder region of the tread portion can be sufficiently exerted.

Further, the width of the high angle region is preferably 1/2 or more of the total width of the belt layer, and the width of the low angle region is preferably 1/8 or more of the total width of the belt layer. By setting the high angle region on the center side and the low angle region on the shoulder side of the belt layer as described above, the rigidity distribution of the tread portion is optimized and uneven wear in the shoulder region of the tread portion is effective. Can be suppressed.

In the present invention, the belt reinforcing layer is set so that the rigidity in the tire circumferential direction per unit width is lower in the second region corresponding to the connecting region than in the first region corresponding to the high angle region. As a means, it is preferable to adopt at least one of the structures described below. That is, in the belt reinforcing layer, it is preferable that the number of band cords driven per unit width is set to be smaller in the second region corresponding to the connecting region than in the first region corresponding to the high angle region. Further, in the belt reinforcing layer, it is preferable that a band cord having a lower rigidity than the band cord arranged in the first region corresponding to the high angle region is arranged in the second region corresponding to the connecting region. Further, in the belt reinforcing layer, the inclination angle of the band cord with respect to the tire circumferential direction is in the range of 5 ° to 30 ° in the second region corresponding to the connecting region, and less than 5 ° in the first region corresponding to the high angle region. It is preferable that Further, in the second region where the distance from the band cord of the belt reinforcing layer to the belt cord of the belt layer arranged on the outer side in the tire radial direction of the belt layer corresponds to the connecting region rather than the first region corresponding to the high angle region. It is preferable that it is large. By adopting these structures, the rigidity of the belt reinforcing layer in the tire circumferential direction per unit width can be adjusted.

In particular, both of the belt layers have a high-angle region, a low-angle region, and a connecting region, and the connecting region of the belt layer located inside and the connecting region of the belt layer located outside are displaced from each other in the tire width direction. Is preferable. By shifting the connecting region of the belt layer located on the inner side and the connecting region of the belt layer located on the outer side from each other in this way, it is possible to avoid the concentration of distortion.

The pneumatic tire of the present invention is preferably a passenger car tire, and particularly preferably a passenger car tire having an aspect ratio of 65% or less. According to the present invention, it is possible to improve high-speed durability while suppressing uneven wear in the shoulder region of the tread portion of a passenger car tire.

FIG. 5 is a cross-sectional view taken along the meridian showing a pneumatic tire according to an embodiment of the present invention. It is a developed view which shows the tread pattern of the pneumatic tire which comprises embodiment of this invention. It is a developed view which shows the belt layer of the pneumatic tire which comprises embodiment of this invention. It is a developed view which shows the belt layer and the belt reinforcement layer of the pneumatic tire which comprises embodiment of this invention. It is a developed view which shows an example of the belt reinforcing layer in the pneumatic tire of this invention. It is a developed view which shows the modification of the belt reinforcing layer in the pneumatic tire of this invention. It is a developed view which shows the other modification of the belt reinforcing layer in the pneumatic tire of this invention. It is a development view which shows the further modification of the belt reinforcing layer in the pneumatic tire of this invention. It is sectional drawing which shows the further modification of the belt reinforcing layer in the pneumatic tire of this invention. It is a developed view which shows the deformation example of the belt layer in the pneumatic tire of this invention.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 4 show a pneumatic tire according to an embodiment of the present invention. In FIGS. 1 to 4, CL is the tire center position, Tc is the tire circumferential direction, and Tw is the tire width direction.

As shown in FIG. 1, the pneumatic tire of the present embodiment has a tread portion 1 extending in the tire circumferential direction and forming an annular shape, and a pair of sidewall portions 2 and 2 arranged on both sides of the tread portion 1. And a pair of bead portions 3 and 3 arranged inside the sidewall portions 2 in the tire radial direction.

A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of carcass cords extending in the tire radial direction, and is folded back from the inside to the outside of the tire around the bead core 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is arranged on the outer periphery of the bead core 5.

On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of belt cords that are inclined with respect to the tire circumferential direction, and are arranged so that the belt cords intersect each other between the layers. As the belt cord constituting the belt layer 7, a steel cord is preferably used. On the outer peripheral side of the belt layer 7, at least one belt reinforcing layer 8 including a plurality of band cords oriented in the tire circumferential direction is arranged. It is desirable that the belt reinforcing layer 8 has a jointless structure in which at least one band cord is aligned and a strip material formed of rubber coating is continuously wound in the tire circumferential direction. As the band cord constituting the belt reinforcing layer 8, an organic fiber cord such as nylon or aramid is preferably used.

As shown in FIG. 2, a plurality of main grooves 10 extending in the tire circumferential direction are formed in the tread portion 1. The main groove 10 includes at least one center main groove 11 and a pair of shoulder main grooves 12 and 12 located outside the center main groove 11. A plurality of land portions 20 are divided in the tread portion 1 by these main grooves 10. The land portion 20 includes a center land portion 21 located between the pair of shoulder main grooves 12 and 12, and a shoulder land portion 22 located outside each shoulder main groove 12. Each center land portion 21 is formed with a plurality of closing grooves 13 having one end opened in the shoulder main groove 12 and the other end ending in the center land portion 21. Further, each shoulder land portion 22 has a plurality of lug grooves 14 extending in the tire width direction and not communicating with the shoulder main groove 12, and shoulder main grooves 12 extending in the tire width direction. A plurality of sipes 15 communicating with each other are alternately formed along the tire circumferential direction.

In the pneumatic tire, as shown in FIG. 3, at least one of the belt layers 7, more preferably both, the inclination angle α of the belt cord C with respect to the tire circumferential direction at the tire center position CL and the belt cord C. The inclination angle β with respect to the tire circumferential direction at the belt terminal position BE satisfies the relationship of 15 ° ≤ β <α ≤ 35 °.

By adopting a structure in which the inclination angle β of the belt cord C at the belt terminal position BE is smaller than the inclination angle α of the belt cord C at the tire center position CL, the tire at the end of the belt layer 7 is adopted. It is possible to increase the rigidity in the circumferential direction and suppress uneven wear in the shoulder region of the tread portion 1. In particular, by setting the difference between the inclination angle α and the inclination angle β to 3 ° or more, the effect of suppressing uneven wear in the shoulder region of the tread portion 1 can be sufficiently exhibited. Here, if the inclination angle β is smaller than 15 °, the rigidity in the tire circumferential direction in the shoulder region of the tread portion 1 becomes excessive, and if the inclination angle α is larger than 35 °, the rigidity in the center region of the tread portion 1 is excessive. Since the rigidity in the tire circumferential direction is excessively reduced, the contact length in the center region becomes too large.

Further, as shown in FIG. 3, the belt layer 7 has a high angle region Ac on the center side in which the inclination angle of the belt cord C is in the range of α ± 1 ° and a range in which the inclination angle of the belt cord C is β ± 1 °. The width Lc of the high angle region Ac is ½ or more of the total width L of the belt layer 7, and the width Ls of each low angle region As is the total width L of the belt layer 7. It is set to be 1/8 or more of. By setting the high angle region Ac on the center side and the low angle region As on the shoulder side of the belt layer 7 as described above, the rigidity distribution of the tread portion 1 can be optimized. Here, if the width Lc of the high angle region Ac is smaller than 1/2 of the total width L of the belt layer 7, the function as the belt layer 7 deteriorates, and the width Ls of the low angle region As is the total width of the belt layer 7. If it is smaller than 1/8 of L, the rigidity in the tire circumferential direction in the shoulder region of the tread portion 1 cannot be sufficiently increased. The width Lc of the high angle region Ac and the width Ls of the low angle region As are set based on the total width L of each belt layer 7.

Further, as shown in FIG. 3, the belt layer 7 has a connecting region Ax in which the angle of the belt cord C gradually changes between the high angle region Ac on the center side and the low angle region As on the shoulder side. .. By providing the connecting region Ax between the high angle region Ac and the low angle region As in this way, it is possible to allow a sudden angle change of the belt cord C.

As described above, the width Lc of the high angle region Ac is 1/2 or more of the total width L of the belt layer 7, and the width Ls of each low angle region As is 1/8 or more of the total width L of the belt layer 7. The width Lx of each connecting region Ax inserted between the high angle region Ac and the low angle region As is 1/8 or less of the total width L of the belt layer 7. Further, the inclination angle γ of the belt cord C between the tire center position CL and the belt terminal position BE with respect to the tire circumferential direction satisfies the relationship of β <γ <α with respect to the inclination angles α and β. Therefore, the belt layer 7 has a point X at which γ = (α + β) / 2.

As described above, when the belt layer 7 adopts a structure in which the inclination angle β of the belt cord C at the belt terminal position BE is smaller than the inclination angle α of the belt cord C at the tire center position CL, the tread portion 1 On the other hand, there is an advantage that uneven wear in the shoulder region of the belt can be suppressed. Distortion is a factor that deteriorates durability.

Therefore, in the above-mentioned pneumatic tire, as shown in FIG. 4, the belt reinforcing layer 8 is arranged so as to cover at least the high angle region Ac and the connecting region Ax of the belt layer 7, and per unit width of the belt reinforcing layer 8. A structure is adopted in which the rigidity in the tire circumferential direction is relatively lower in the second region A2 corresponding to the connecting region Ax than in the first region A1 corresponding to the high angle region Ac. The first region A1 of the belt reinforcing layer 8 is a range of L × 2/5 centered on the tire center position CL with respect to the total width L of the belt layer 7, and the second region A2 of the belt reinforcing layer 8 is the belt cord C. The range is 10 mm (20 mm in total) on both sides in the tire width direction around the point X at which the inclination angle γ with respect to the tire circumferential direction is (α + β) / 2. By setting the rigidity of the belt reinforcing layer 8 in the tire circumferential direction per unit width as described above, it is possible to alleviate the distortion generated around the connecting region Ax of the belt layer 7 during tire running and improve the durability. .. This makes it possible to ensure good durability while suppressing uneven wear in the shoulder region of the tread portion 1. For example, in the second region A2 of the belt reinforcing layer 8 corresponding to the connecting region Ax of the belt layer 7, the rigidity G per unit width is set in the range of 0.05 kN / mm to 0.6 kN / mm, and the height of the belt layer 7 is high. In the first region A1 of the belt cover layer 8 corresponding to the angle region Ac, it is preferable that the rigidity G is higher than that in the second region A2 and the difference between the two is 0.3 kN / mm.

FIG. 5 shows an example of the belt reinforcing layer in the pneumatic tire of the present invention. As shown in FIG. 5, when the first region A1 and the second region A2 are defined in the belt reinforcing layer 8, the number N of band cords B driven per unit width is in the second region A2 rather than in the first region A1. It is set to be less. As a result, the distortion generated around the connecting region Ax of the belt layer 7 when the tire is running can be alleviated, and the durability can be improved.

FIG. 6 shows a modified example of the belt reinforcing layer in the pneumatic tire of the present invention. In FIG. 6, the belt reinforcing layer 8 has a jointless structure in which a strip material formed by aligning a plurality of band cords B and coating them with rubber is continuously wound in the tire circumferential direction, and has a first region A1. In, the strip material is densely wound so as to be adjacent to each other in each lap, and in the second region A2, the strip material is sparsely wound at intervals in each lap. For example, when the width of the strip material is 10 mm, the distance between the strip materials is set to 2 mm to 5 mm in the second region A2. As a result, the number N of band cords B driven per unit width of the belt reinforcing layer 8 is set to be smaller in the second region A2 than in the first region A1. As a result, the distortion generated around the connecting region Ax of the belt layer 7 when the tire is running can be alleviated, and the durability can be improved.

FIG. 7 shows another modification of the belt reinforcing layer in the pneumatic tire of the present invention. In FIG. 7, the band cords B constituting the belt reinforcing layer 8 are arranged at equal intervals over the entire area, but two types of band cords B1 and B2 having different materials are used as the band cords B. That is, the band cord B1 is arranged in the first region A1 of the belt reinforcing layer 8, the band cord B2 is arranged in the second region A2, and the tensile rigidity of the band cord B2 is higher than the tensile rigidity of the band cord B1. It's getting low. As a result, the distortion generated around the connecting region Ax of the belt layer 7 when the tire is running can be alleviated, and the durability can be improved. For example, a hybrid cord of nylon and aramid is used as the band code B1 of the first region A1, and a nylon cord is used as the band code B2 of the second region A2.

FIG. 8 shows still another modification of the belt reinforcing layer in the pneumatic tire of the present invention. As shown in FIG. 8, in the belt reinforcing layer 8, the inclination angle θ of the band cord B with respect to the tire circumferential direction is in the range of 0 ° to 30 °, and the inclination angle θ is less than 5 ° in the first region A1. On the other hand, in the second region A2, the inclination angle θ is set in the range of 5 ° to 30 °. As a result, the distortion generated around the connecting region Ax of the belt layer 7 when the tire is running can be alleviated, and the durability can be improved. However, if the inclination angle θ of the band code B with respect to the tire circumferential direction becomes larger than 30 °, the high-speed durability will be adversely affected.

FIG. 9 shows still another modification of the belt reinforcing layer in the pneumatic tire of the present invention. In FIG. 9, the distance D from the band cord B of the belt reinforcing layer 8 to the belt cord C of the belt layer 7B arranged on the outer side in the tire radial direction of the belt layer 7 is larger in the second region A2 than in the first region A1. It has become. In particular, when the distance between the cords at the tire center position CL in the first region A1 is D1 and the distance between the cords at the point X in the second region A2 is D2, the relationship of 1.3 ≦ D2 / D1 <2.0 is established. Is pleased. As a result, the distortion generated around the connecting region Ax of the belt layer 7 when the tire is running can be alleviated, and the durability can be improved. If the ratio D2 / D1 is larger than 2.0, the heat generated by the coated rubber increases, which may adversely affect the durability. In order to realize such a configuration, it is possible to locally thicken the coated rubber of the belt reinforcing layer 8 or add a rubber sheet locally between the belt layer 7 and the belt reinforcing layer 8. is there.

FIG. 10 shows another modification of the belt layer in the pneumatic tire of the present invention. As shown in FIG. 10, when both the belt layers 7 have a high angle region Ac, a low angle region As, and a connecting region Ax, the connecting region Ax (hatched portion) of the belt layer 7A located inside in the tire radial direction and the tire. It is preferable that the connecting region Ax (hatched portion) of the belt layer 7B located on the outer side in the radial direction is deviated from each other in the tire width direction. By shifting the connecting region Ax of the belt layer 7A located inside and the connecting region Ax of the belt layer 7B located outside from each other in this way, it is possible to suppress the local occurrence of strain. The amount of deviation Dx between the center positions of the connecting region Ax of the belt layer 7A and the connecting region Ax of the belt layer 7B is preferably 3 mm or more.

In the above-described embodiment, the case where the belt cover layer is a full cover that covers the entire belt layer has been described, but in the present invention, as the belt cover layer, a center cover that covers only the high angle region and the connecting region of the belt layer is adopted. It is possible to combine the center cover and the full cover, combine the shoulder cover and the full cover that cover only the low angle region of the belt layer, and stack the center covers of a plurality of layers.

The above-mentioned pneumatic tire is suitable as a passenger car tire having a flatness of 65% or less, and can reduce the rolling resistance of the passenger car tire and improve the uneven wear resistance.

With a tire size of 205 / 55R16 91V, a carcass layer mounted between a pair of bead portions, two belt layers arranged outside the carcass layer in the tread portion in the tire radial direction, and a belt layer outside the tire radial direction. In the pneumatic tire provided with the one-layer belt reinforcing layer arranged in the above, the tires of the conventional example, the comparative example and the examples 1 to 8 in which the structure of the belt layer and the structure of the belt reinforcing layer are set as shown in Table 1. Made. However, in the present specification, Examples 1, 3, 5, 7, and 8 are reference examples.

In the conventional example, a normal belt layer having the same inclination angle α with respect to the tire circumferential direction at the tire center position of the belt cord and an inclination angle β with respect to the tire circumferential direction at the belt terminal position of the belt cord, and the belt layer. A belt reinforcement layer (full cover) with a uniform structure covering the entire area was adopted.

In the comparative example, the inclination angle β with respect to the tire circumferential direction at the belt terminal position of the belt cord is set to be smaller than the inclination angle α with respect to the tire circumferential direction at the tire center position of the belt cord, and the high angle region and the connecting region are used. A belt layer having a low angle region and a belt reinforcing layer (full cover) having a uniform structure covering the entire area of the belt layer were adopted.

In Examples 1 to 8, the inclination angle β with respect to the tire circumferential direction at the belt terminal position of the belt cord is set to be smaller than the inclination angle α with respect to the tire circumferential direction at the tire center position of the belt cord, and the high angle region is defined. A belt layer having a connecting region and a low-angle region and a belt reinforcing layer (FIGS. 5 to 9) covering the entire belt layer were adopted.

In Table 1, the position of the point X and the position of the outer end of each belt layer are shown by the distance in the tire width direction from the tire center position.

These test tires were evaluated for uneven wear resistance and high-speed durability in the shoulder region by the following test method, and the results are also shown in Table 1.

Uneven wear resistance in the shoulder area:
Each test tire is attached to a wheel with a rim size of 16 x 6.5J and mounted on a friction energy measurement tester, and the average friction energy in the shoulder region of the tread is measured under the conditions of an air pressure of 230 kPa and a load of 4.5 kN. did. The measured value is the average of the frictional energies measured at two points in the tire width direction and two points in the tire circumferential direction at intervals of 10 mm, for a total of four points. The evaluation result is shown by an index of 100 in the conventional example using the reciprocal of the measured value. The larger the index value, the better the uneven wear resistance.

High speed durability:
Each test tire was assembled on a wheel with a rim size of 16 x 6.5J and mounted on a drum tester. After running under the conditions described in 30, the test speed was increased by 10 km / h every 10 minutes of steps, and the number of steps cleared from the start of the test was determined. The evaluation result is shown by an index of 100 in the conventional example. The larger the index value, the better the high-speed durability.

As can be seen from Table 1, the tires of Examples 1 to 8 had excellent uneven wear resistance in the shoulder region and also had good high-speed durability as compared with the conventional examples. On the other hand, the tire of the comparative example had good uneven wear resistance in the shoulder region, but had deteriorated high-speed durability.

1 Tread part 2 sidewall part 3 bead part 4 carcass layer 5 bead core 6 bead filler 7 belt layer 8 belt reinforcement layer 10 main groove 11 center main groove 12 shoulder main groove Ac belt layer high angle area As belt layer low angle area Ax Belt layer connection area A1 Belt reinforcement layer first area A2 Belt reinforcement layer second area B Band code C Belt code CL Tire center position BE Belt terminal position

Claims (9)

A carcass layer mounted between a pair of bead portions, two belt layers arranged outside the tire radial direction of the carcass layer in the tread portion, and at least one layer arranged outside the tire radial direction of the belt layer. In a pneumatic tire provided with a belt reinforcing layer of the above, the belt layer includes a plurality of belt cords inclined with respect to the tire circumferential direction, and the belt cords are arranged so as to intersect each other between layers.
In at least one of the belt layers, the inclination angle α of the belt cord with respect to the tire circumferential direction at the tire center position and the inclination angle β of the belt cord with respect to the tire circumferential direction at the belt terminal position are 15 ° ≦ β <α. Satisfying the relationship of ≤35 °,
The belt layer includes a high angle region on the center side in which the inclination angle of the belt cord is in the range of α ± 1 ° and a low angle region on the shoulder side in which the inclination angle of the belt cord is in the range of β ± 1 °. The belt cord has a connecting region in which the angle of the belt cord gradually changes between the high angle region and the low angle region.
The belt reinforcing layer is arranged so as to cover at least the high angle region and the connecting region of the belt layer, and the rigidity in the tire circumferential direction per unit width is higher than that of the first region corresponding to the high angle region. It is set to be low in the second area corresponding to the connecting area,
In the belt reinforcing layer, the inclination angle of the band cord with respect to the tire circumferential direction is in the range of 5 ° to 30 ° in the second region corresponding to the connecting region, and less than 5 ° in the first region corresponding to the high angle region. pneumatic tire, characterized in that it has become. The distance from the band cord of the belt reinforcing layer to the belt cord of the belt layer arranged on the outer side in the tire radial direction of the belt layer corresponds to the connecting region rather than the first region corresponding to the high angle region. The pneumatic tire according to claim 1 , wherein the tire is enlarged in the region. A carcass layer mounted between a pair of bead portions, two belt layers arranged outside the tire radial direction of the carcass layer in the tread portion, and at least one layer arranged outside the tire radial direction of the belt layer. In a pneumatic tire provided with a belt reinforcing layer of the above, the belt layer includes a plurality of belt cords inclined with respect to the tire circumferential direction, and the belt cords are arranged so as to intersect each other between layers.
In at least one of the belt layers, the inclination angle α of the belt cord with respect to the tire circumferential direction at the tire center position and the inclination angle β of the belt cord with respect to the tire circumferential direction at the belt terminal position are 15 ° ≦ β <α. Satisfying the relationship of ≤35 °,
The belt layer includes a high angle region on the center side in which the inclination angle of the belt cord is in the range of α ± 1 ° and a low angle region on the shoulder side in which the inclination angle of the belt cord is in the range of β ± 1 °. The belt cord has a connecting region in which the angle of the belt cord gradually changes between the high angle region and the low angle region.
The belt reinforcing layer is arranged so as to cover at least the high angle region and the connecting region of the belt layer, and the rigidity in the tire circumferential direction per unit width is higher than that of the first region corresponding to the high angle region. It is set to be low in the second area corresponding to the connecting area,
The distance from the band cord of the belt reinforcing layer to the belt cord of the belt layer arranged on the outer side in the tire radial direction of the belt layer corresponds to the connecting region rather than the first region corresponding to the high angle region. Pneumatic tires characterized by being larger in the area. The pneumatic tire according to any one of claims 1 to 3, wherein the difference between the inclination angle α and the inclination angle β is 3 ° or more. The width of the high angle region is 1/2 or more of the total width of the belt layer, and the width of the low angle region is 1/8 or more of the total width of the belt layer . Pneumatic tires listed in either. The belt reinforcing layer is characterized in that the number of band cords driven per unit width is set to be smaller in the second region corresponding to the connecting region than in the first region corresponding to the high angle region. The pneumatic tire according to any one of claims 1 to 5. The claim is characterized in that, in the belt reinforcing layer, a band cord having a lower rigidity than the band cord arranged in the first region corresponding to the high angle region is arranged in the second region corresponding to the connecting region. The pneumatic tire according to any one of Items 1 to 6. Both of the belt layers have the high angle region, the low angle region, and the connecting region, and the connecting region of the belt layer located inside and the connecting region of the belt layer located outside are displaced from each other in the tire width direction. The pneumatic tire according to any one of claims 1 to 7, wherein the tire is provided. The pneumatic tire according to any one of claims 1 to 8, wherein the pneumatic tire is a passenger car tire.

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