JP6008708B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  Conventionally, as a pneumatic tire with improved performance on ice, the present applicant has a block group in which a plurality of independent blocks are closely packed together, and the number density of the blocks in the reference area is within a predetermined range. A tire having a tread pattern has been proposed (see, for example, Patent Document 1). According to this tire, it is possible to dramatically improve the performance on ice by ensuring excellent ground contact and edge effect and efficiently removing the water film by the block.

International Publication 2010/032606 Pamphlet

  However, the inventors have studied the above tires. However, in the above tires, since the small blocks are densely arranged at a high number density, the rigidity of the blocks alone is low, and particularly the tire rolling. It has been newly found that there is a problem that a large deformation occurs at each input on the kicking side of the block where a large contact pressure is applied during the movement, and there is a possibility that a crack may occur on the wall surface of the block. It was also found that when the block has sipes extending in the tread width direction, the rigidity of the block land portions at both ends in the tread circumferential direction defined by the sipes is lowered, and cracks are particularly likely to occur.

  An object of the present invention is to solve the above-described problem, and to provide a pneumatic tire capable of suppressing the occurrence of cracks while ensuring on-ice performance.

The gist configuration of the present invention is as follows.
The pneumatic tire of the present invention, the tread surface is partitioned by the groove, there is an area of each of the tread in the range of 100 to 200 mm ^2, the tread shape is a plurality of blocks is a more polygonal pentagonal in the tread circumferential direction A plurality of block rows arranged in the tread width direction are provided,
The blocks are densely arranged in a staggered manner in which the positional relationship between the blocks in adjacent block rows is different from each other in the tread circumferential direction,
The tread shape is a pentagonal or more polygonal block, the two sides on both sides of the tread circumferential direction are arranged so as to extend in the tread width direction,
Of the two sides, the length of the side of the block when the tire is rotated is a (mm), and the length of the block in the tread circumferential direction is b (mm). when the ratio a / b is Ri 0.5 ultra der,
The ratio e / b is more than 1 and 2.0 or less, where e (mm) is the maximum length in the tread circumferential direction of the pentagonal or more polygonal block .
As a result, it is possible to increase the rigidity of the end of the block on the kick-out side and suppress the occurrence of cracks while ensuring on-ice performance.
Moreover, it is because the length component of the block in the tread circumferential direction can be increased to further ensure the on-ice performance of the tire.
“Pentagon” and “polygonal shape” mean shapes and sides when the tread tread is developed and viewed in plan. “Tread surface” means that the pneumatic tire is attached to an applicable rim, filled with a specified internal pressure, loaded with a maximum load, and in contact with the road surface in a reference state. It means the outer peripheral surface over the entire circumference.
Further, “two sides extend in the tread width direction” means that the two sides extend at an angle of 0 ° to 20 ° with respect to the tread width direction.
Here, the “applicable rim” is a rim in which an industrial standard effective for the region where the tire is produced and used is determined for each tire, and is a standard rim for JATMA (YEAR BOOK of the Japan Automobile Tire Association). , TRA (THE TIRE and RIM ASSOCIATION INC. YEAR BOOK) “Design Rim”, ETRTO (European Tire and Rim Technical Organization STANDARD MANUAL) “Maximum load load” refers to the maximum load of a tire defined by the above standards such as JATMA according to the tire size, and “specified internal pressure” refers to the air pressure (maximum air pressure) corresponding to the maximum load load. Point to.
However, in the following description, unless otherwise specified, a tire in an applied rim, a specified internal pressure, and an unloaded state will be described.

In the pneumatic tire according to the present invention, when the length of the side on the stepping side of the block during rotation of the two sides is c (mm), the ratio c / b is 0. Preferably greater than .5.
Thereby, while ensuring on-ice performance, the rigidity of the end portion on the stepping-in side of the block can be increased to further suppress the occurrence of cracks.

Moreover, in the pneumatic tire of the present invention, the polygonal block of the pentagon or more has one or more sipes extending in the tread width direction,
It is preferable that the sipe is disposed at a position spaced apart by 4.0 mm or more in the tread circumferential direction from the tread circumferential end of the block.
It is because crack resistance can be ensured.

Here, in the pneumatic tire of the present invention, it is preferable that a connecting portion for connecting the blocks in the tread circumferential direction is provided between at least some of the blocks adjacent in the tread circumferential direction.
This is because the occurrence of cracks can be suppressed by increasing the rigidity of the block while ensuring the performance on ice.

In the pneumatic tire of the present invention, when the height of the block is H (mm) and the height of the connecting portion is h (mm), the ratio h / H is 10% or more and 70% or less. Preferably there is.
This is to prevent the above-mentioned connecting portion from coming into contact with the ground until a certain amount of wear during the progress of wear of the tire while sufficiently exerting the above-described crack suppressing effect.
Here, “the height H (mm) of the block” and “the height h (mm) of the connecting portion” mean the height from the groove bottom of the groove adjacent to the connecting portion, as shown in FIG. For the former, if the height of the block is not constant, the maximum height of the block shall be said. For the latter, if the height of the connecting portion is not constant, the maximum height of the connecting portion. It shall be said.

Furthermore, in the pneumatic tire according to the present invention, the side walls on both sides in the tread width direction of the connecting portion are inclined outward from the connecting portion toward the inner side in the tire radial direction , and the tread width of the connecting portion. The inclination angle θ (°) with respect to the tire radial direction of the sidewalls on both sides in the direction is preferably 0 ° or more and 5 ° or less.
This is because drainage performance and snow drainage performance can be secured while securing the rigidity of the block.
Here, “inclination angle θ (°)” means an angle when a tire is mounted on an applicable rim, filled with a specified internal pressure, and in a no-load state, and when the inclination angle is not constant, The minimum inclination angle of the side wall shall be said.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can suppress generation | occurrence | production of a crack can be provided, ensuring the performance on ice.

It is a partial development figure showing a tread pattern of a tire concerning one embodiment of the present invention. (A) It is a top view which shows the dimension of a hexagonal block. (B) It is a top view which shows the dimension of an octagon-shaped block. It is a partial development view showing a tread pattern of a tire concerning other embodiments of the present invention. It is a figure shown about the height H of a block, and the height h of a connection part. It is a figure shown about inclination-angle (theta) of the tire width direction both side wall of a connection part. It is a partial development figure showing the tread pattern of the tire concerning a comparative example. It is a partial development view showing a tread pattern of a tire concerning an example of an invention. It is a partial development figure showing the tread pattern of the tire concerning a comparative example.

  Hereinafter, a pneumatic tire (hereinafter, also referred to as a tire) according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial development view showing a tread pattern of a tire according to an embodiment of the present invention. In addition, about the internal structure of a tire, since it is the same as that of the past, description is abbreviate | omitted.

  As shown in FIG. 1, the tire includes two circumferential main grooves 2 extending in the tread circumferential direction on the tread tread surface 1 in the illustrated example, and a widthwise groove 3 extending inward in the tread width direction TE from the tread end TE. And a plurality of narrow grooves 4 extending in a zigzag shape in the tread circumferential direction. As shown in FIG. 1, these grooves 2, 3, 4 are used to form a polygonal block having a tread shape of a pentagon or more, in the illustrated example (the one adjacent to the circumferential main groove 2 is a pentagonal shape). A plurality of blocks 5 each having a hexagonal shape are defined. As shown in FIG. 1, a plurality of block rows in which a plurality of blocks 5 are arranged in the tread circumferential direction are provided in the tread width direction. In the illustrated example, the blocks 5 between the block rows adjacent in the tread width direction have a phase difference in the tread circumferential direction (in the illustrated example, a phase difference that is half the tread circumferential length of the block is provided. ) Arranged in a staggered pattern. Further, in the illustrated example, each block 5 is provided with three sipes 6 extending substantially in the tread width direction. In the present embodiment, the block 5 has a hexagonal shape, but may be, for example, an octagonal shape.

Here, the area of the tread of the block 5 is in the range of 100 to 200 mm ² .

Moreover, in this tire, as shown in FIG. 1, two sides 5a and 5b on both ends of the block 5 in the tread circumferential direction extend in the tread width direction.
Here, as shown in FIGS. 2A and 2B, the length of one side 5a of the two sides of the block 5 at both ends in the circumferential direction of the tread is a (mm), and the length of the other side 5b. The length in the tread width direction at the center position in the tread circumferential direction of the block 5 is b (mm).
At this time, in the tire of the present invention, it is important that the ratio a / b is more than 0.5.
Hereinafter, the operation and effect when the tire is mounted on the vehicle so that the one side 5a is on the kicking end side of the block 5 when the tire rotates will be described.

In the tire according to the present embodiment, a configuration in which the blocks 5 are densely arranged while ensuring a sufficient groove area on the tread surface is adopted, so that the total edge length and edge direction of each block 5 (different directions) The number of edges facing the surface can be increased, and an excellent edge effect can be exhibited. Moreover, since the area of the tread surface of each block 5, ie, the ground contact area, is reduced, the ground contact performance of each block can be improved, and high performance on ice can be exhibited. In addition, since the distance from the central area of the block 5 to the peripheral edge of the block 5 can be reduced by reducing the ground contact area of each block 5, the effect of removing the water film by the block 5 can be improved. Therefore, according to the tire of the present embodiment, it is possible to dramatically improve the performance on ice by ensuring excellent grounding performance and edge effect and efficiently removing the water film by the block 5. . In addition, if the area of the tread surface of the block 5 is in the range of 100 to 200 mm ² , both the block rigidity and the edge effect can be achieved at a higher level, and the performance on ice can be improved more effectively. Can do. That is, when the ground contact area of each block 5 is more than 200 (mm ² ), it is difficult to realize a high edge effect. On the other hand, if the ground contact area of each block 5 is less than 100 (mm ² ), the ground contact area of the block 3 Is too small to achieve the required block rigidity.

  Furthermore, according to the tire of the present embodiment, since the ratio a / b is more than 0.5, for example, the block is a regular hexagon (in this case, the ratio a / b is 0.5). Thus, it is possible to secure the length in the width direction of the edge of the kick-out side end of 5, and to increase the rigidity of the kick-out side end of the block, which has a particularly large contact pressure, thereby suppressing the occurrence of cracks.

Furthermore, in the tire of the present invention, the ratio c / b is preferably more than 0.5.
This is because it is possible to increase the rigidity of both ends in the circumferential direction of the tread (both the kicking side and the stepping side) and suppress the occurrence of cracks.

Here, the ratio a / b is more preferably 0.55 or more, and further preferably 0.6 or more.
By setting the ratio a / b in the above range, it is possible to further secure the edge length of the end portion on the kick-out side of the block 5 at the time of tire rotation, and further suppress the occurrence of cracks. Because.
On the other hand, the ratio a / b is preferably 0.7 or less. This is because the responsiveness of the movement of the block with respect to the input from multiple directions in the polygonal block can be limited to the circumferential direction and the width direction.
In the present invention, the block preferably has a polygonal shape in which all inner angles are less than 180 °. This is because it is possible to prevent variation between the high rigidity portion and the low rigidity portion in the block tread surface.

The ratio c / b is more preferably 0.55 or more, and further preferably 0.6 or more.
By setting the ratio c / b in the above range, the edge length of the stepped side end of the block 5 at the time of tire rotation can be further secured, and the occurrence of cracks can be further suppressed. It is.
On the other hand, the ratio c / b is preferably 0.7 or less. This is because the responsiveness of the movement of the block with respect to the input from multiple directions in the polygonal block can be limited to the circumferential direction and the width direction.

Furthermore, in the pneumatic tire of the present invention, the ratio a / c is preferably 0.9 to 1.1.
This is because by setting the ratio of the lengths of the two sides on both ends in the tread circumferential direction of the block within the above range, the blocks can be arranged densely and the on-ice performance of the tire can be ensured.

Here, as shown in FIGS. 2A and 2B, when the maximum length in the tread circumferential direction of the block 5 is e (mm), in the tire of the present invention, the ratio e / b is 1 Ru ultra 2.0 or less der.
By setting the ratio e / b to be greater than 1, the length of the tread circumferential direction component of the block 5 can be secured, the rigidity in the tread circumferential direction can be secured, and the on-ice performance of the tire can be improved. It is. In addition, for example, as shown in FIG. 1, when a plurality of sipes are provided in a block, the occurrence of cracks or chipping in a land portion between sipes is suppressed by setting a certain distance from the block wall to the sipes. Because it can be done.
On the other hand, by setting the ratio e / b to 2.0 or less, it is possible to shorten the block length in the circumferential direction and secure the rigidity in the width direction, and to ensure the performance on ice when a lateral force is generated. is there.

In the present invention, as shown in FIG. 1, the block 5 preferably has a sipe 6 extending substantially in the tread width direction. In particular, the block 5 has two or three sipes 6 extending substantially in the tread width direction. Is preferred. This is because the edge component extending in the tread width direction (edge component with respect to the tread circumferential direction) can be ensured, and the on-ice performance of the tire can be more sufficiently ensured. On the other hand, when a sipe is provided, the rigidity of the end portion in the circumferential direction of the tread of the block 5 is lowered, but according to the present invention, the ratio a / b is set in the above range, so that the block 5 This is because the occurrence of cracks can be effectively suppressed even in such a case because the rigidity of the end portion in the tread circumferential direction is increased.
The “sipe” is a thin notch that is cut from the surface of the block to the inside and can be closed at the time of ground contact. In order to obtain the above-mentioned effect, The width is preferably 0.2 to 1.0 mm, and the depth of the sipe 6 is preferably 5.5 to 9.0 mm.
In the present embodiment, the sipe communicates with the circumferential main groove 2, the width direction groove 3, and the narrow groove 4. From the viewpoint of maintaining the rigidity of the block and further improving the crack resistance. When the sipe 6 is provided in the block 5, one or both ends of the sipe 6 are not communicated with the circumferential main groove 2, the width direction groove 3, and the narrow groove 4, so that the inside of the land portion of the block 5 It can also extend so that it may remain. In particular, the sipe 6 formed in the block 5 adjacent to the widthwise groove 3 has an end on the side adjacent to the widthwise groove 3 not communicating with the widthwise groove 3, and the other end is a narrow groove. It is preferable to communicate with 4 etc. This is because performance on ice and anti-cracking performance can be achieved at a higher level.

Here, as shown in FIGS. 2A and 2B, the sipe 6 is preferably disposed at a position separated from the end of the block 5 in the tread circumferential direction by 4.0 mm or more in the tread circumferential direction. More preferably, it is arranged at a position separated by 0 mm or more.
In the case of a sipe extending in a zigzag shape as in the illustrated example, the zigzag center line (virtual line with zigzag amplitude of 0) of the sipe is 4 in the tread circumferential direction from the tread circumferential end of the block 5. It shall be arranged to be spaced apart by 0.0 mm or more (preferably 5.0 mm or more).
This is because the crack resistance can be ensured by preventing the rigidity at each end of the block 5 in the tread circumferential direction from becoming too low.

Further, in the tire of the present invention, as shown in FIG. 3, it is preferable that a connecting portion for connecting the blocks 5 in the tread circumferential direction is provided between at least some of the blocks 5 adjacent in the tread circumferential direction. .
This is because the rigidity of the end portion in the tread circumferential direction of the block is increased, the deformation of the block can be suppressed, and the occurrence of cracks can be further suppressed.
In particular, when the tire width direction region corresponding to 80% of the tread contact width TW centered on the tire equatorial plane in the reference state is a center portion C, at least the center portion C is adjacent to the tread circumferential direction. It is preferable to provide a connecting portion between the blocks in the tread circumferential direction. This is because the above effects can be obtained particularly in the center portion where cracks are likely to occur.
Here, the “tread grounding width TW” refers to the maximum width in the tread width direction of the grounding surface in the reference state.

In addition, like this embodiment, it can be set as the structure which does not provide the connection part 7 between the blocks 5 in the block row | line | column adjacent to the circumferential direction main groove 2 on both sides of a tread width direction.
Thereby, drainage performance and snow drainage performance can be ensured, and grounding performance can also be secured. On the other hand, a connection part can also be provided between all the blocks 5 adjacent to the tread circumferential direction.

Further, in the present invention, when the connecting portion 7 described above is provided, the height of the block 5 (equal to the depth of the narrow groove 4) is set to H (mm) as shown in FIG. When the height of h is mm (mm), the ratio h / H is preferably 10% or more and 70% or less. This is because by setting the ratio h / H to 10% or more, the rigidity of the circumferential end of the block can be further increased. In particular, when a so-called cap-and-base structure is adopted for the tread rubber, cracks are likely to occur near the interface between the cap rubber and the base rubber, which is usually located near the groove bottom. The rigidity in the vicinity of the interface can be reliably increased. On the other hand, by setting the ratio h / H to 70% or less, even if the height of the block is reduced due to wear, the connecting portion can be prevented from being grounded until a constant wear.
More specifically, the height H (mm) of the block is preferably 5.0 to 9.0 mm, and the height h (mm) of the connecting portion is 4.0 to 6.0 mm. Is preferred.

  In the present invention, when the connecting portion 7 is provided, as shown in FIG. 5, the inclination angle θ (°) with respect to the tire radial direction of the side wall 7 a on both sides in the tread width direction of the connecting portion 7 is 0 ° or more. It is preferably 5 ° or less. By setting the inclination angle θ to 0 ° or more, block rigidity can be secured and cracks can be suppressed. On the other hand, by setting the inclination angle θ to 5 ° or less, drainage performance and snow drainage performance are ensured. This is because the grounding property can be secured.

  In addition, according to the tire of the present embodiment, since the blocks 5 are densely arranged in a zigzag shape in the tread circumferential direction between the adjacent block rows in the tread width direction, more tires of the block 5 can be moved during tire rolling. Under the formation, each edge can be allowed to act sequentially to exert a more excellent edge effect. In addition, since the ground contact timing to the road surface can be shifted between the blocks 5 adjacent in the tread width direction, pattern noise can also be reduced.

By the way, in this invention, it is preferable that the negative rate N of the tread surface is 5% to 50%. This is because when the negative rate N of the tread surface is less than 5%, the groove area is too small and the drainage performance becomes insufficient. On the other hand, when it exceeds 50%, the ground contact area becomes too small and steering stability is lowered. It is because there is a possibility of doing.
The “negative ratio N of the tread surface” means the ratio of the groove area to the ground contact area in the reference state.

Moreover, in this invention, it is preferable to provide the circumferential direction main groove 2 and the width direction groove | channel 3 as shown in FIG. This is because drainage can be secured.
Here, the circumferential groove 2 refers to a groove extending substantially in the tread circumferential direction and having a groove width of 2.0 mm or more, and the shape is not particularly limited, and includes a linear shape, a zigzag shape, a bent shape, and the like. . Moreover, it is preferable that the groove width of the circumferential groove | channel 2 shall be 3-15 mm. This is because the ground contact area can be ensured by ensuring that the negative rate does not become too large while ensuring drainage. Moreover, it is preferable that the depth of the circumferential groove | channel 2 shall be 8.0-10.5 mm. This is to ensure the rigidity of the block while ensuring drainage.
Moreover, the width direction groove | channel 3 shall extend in a tread width direction substantially, and shall mean the groove | channel whose groove width is 1.5 mm or more. It is preferable that the width direction groove | channel 3 inclines and extends at an angle of 0-60 degrees with respect to the tread width direction. Furthermore, it is preferable that the groove width of the width direction groove | channel 3 shall be 2-15 mm. This is because the ground contact area can be ensured by ensuring that the negative rate does not become too large while ensuring drainage. Moreover, it is preferable that the depth of the width direction groove | channel 3 shall be 8.0-10.5 mm. This is to ensure the rigidity of the block while ensuring drainage.
In the present invention, as shown in FIG. 1, the width direction groove 3 extends from the tread ground end TCE inward in the tread width direction, and is defined by the tread ground end TCE and the circumferential groove 2. It is preferable to extend to. In other words, it is preferable that the circumferential main groove 2 whose opening width to the tread tread 1 is 3 mm or more and the width direction groove 3 whose opening width to the tread tread 1 is 2 mm or more do not communicate directly.
This is because a ground contact area can be ensured and turbulence caused by the communication of these grooves can be suppressed.
Furthermore, in this case, as shown in FIG. 1, it is more preferable that the circumferential main groove 2 and the width direction groove 3 communicate with each other through the narrow groove 4.
This is because the snow column shear force can be effectively exhibited.

  Furthermore, as shown in FIG. 1, when the narrow groove 4 is provided, it is preferable that the narrow groove 4 has a width that allows the blocks to be individually movable without being constrained by each other. Specifically, the thickness is preferably 0.7 to 3 mm.

In order to confirm the effects of the present invention, the tires according to Invention Examples 1 to 7, Reference Example 8, Invention Examples 9, 10, Reference Example 11 and Invention Examples 12 to 18 and the tires according to Comparative Examples 1 and 2 were prototyped. The following on-ice performance and crack resistance were evaluated.
The specifications and evaluation results of each tire are shown in Table 1 below.
In Table 1, “Figure” shows a developed view of the tread surface of each tire, and in particular, FIGS. 1 and 7 are views showing the tread surface of the tire according to the invention example. FIG. 8 is a view showing a tread surface of a tire according to a comparative example. Of the three sipes, each of the two sipes positioned on both ends of the tread circumferential direction is connected to each of the blocks on both sides of the tread circumferential direction of the block in which the sipes are provided. , The distance separated in the tread circumferential direction, and “e” represents the maximum length (mm) of the block in the tread circumferential direction.
Each tire was mounted on the vehicle such that the side 5a (side with a (mm) length) was the kicking side and the side 5b (side with c (mm) length) was the stepping side.

<Performance on ice>
Each of the tires having a tire size of 195 / 65R15 was assembled on a rim having a rim size of 15 × 6.0 J, an internal pressure was set to 240 kPa, and evaluation was performed by performing a braking test on an icy road surface.
In Table 1, the evaluation result is shown as an index when the evaluation result of the tire according to Comparative Example 1 is set to 100, and the larger the value, the better the performance on ice.
<Crack resistance>
Each tire having a tire size of 195 / 65R15 was assembled on a rim having a rim size of 15 × 6.0 J, the internal pressure was set to 240 kPa, a constant input was applied, and the occurrence of cracks was evaluated.
In Table 1, the evaluation result is shown as an index when the evaluation result of the tire according to Comparative Example 1 is set to 100, and a larger numerical value indicates better crack resistance performance.

As shown in Table 1, the tires according to Invention Examples 1, 3 to 7, 9, 10, 12 to 18, and Reference Examples 8 and 11 all ensure on-ice performance as compared with Comparative Example 1. However, it turns out that it is excellent in crack resistance. Moreover, it turns out that the tire concerning the invention example 2 is excellent in crack resistance, ensuring the performance on ice compared with the comparative example 2. FIG.
In addition, it can be seen from comparison of Invention Examples 1, 3, and 4 that Invention Examples 3 and 4 in which the value of the ratio a / b is optimized have further improved crack resistance.
Furthermore, it can be seen from Invention Examples 5 and 7 that Invention Examples 6 and 7 in which the value of the ratio c / b is optimized are more excellent in crack resistance than Invention Example 5.
Moreover, it can be seen from the comparison of Invention Examples 5, 9, and 10 and Reference Examples 8 and 11 that the performance on ice is improved in Invention Examples 5, 9, and 10 in which the ratio e / b is optimized.
Furthermore, it turns out that the invention example 5 which optimized the arrangement | positioning position of the sipe is excellent in crack resistance from the invention example 12. FIG.
Furthermore, it turns out that the invention example 13 which provided the connection part which connects between blocks in the tread circumferential direction has improved crack resistance from the invention example 5. FIG.
In addition, it can be seen from comparison between Invention Examples 14 and 15 that Invention Example 15 in which the value of the ratio h / H is optimized has improved crack resistance than Invention Example 14.
Furthermore, it can be seen from comparisons of Invention Examples 16 to 18 that Invention Examples 16 and 17 in which the inclination angle θ of the side wall of the connecting portion is optimized have better performance on ice than Invention Example 18.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can suppress generation | occurrence | production of a crack can be provided, ensuring the performance on ice.

1 tread surface 2 circumferential main groove 3 width direction groove 4 narrow groove 5 block 6 sipe 7 connecting portion CL tire equatorial surface TE tread edge

Claims (6)

The tread surface is defined by a groove, the area of each of the tread surface in the range of 100 to 200 mm ^2, a block row which tread surface shape formed by arranging a plurality of blocks is a more polygonal pentagonal in the tread circumferential direction, Provide multiple rows in the tread width direction,
The blocks are densely arranged in a staggered manner in which the positional relationship between the blocks in adjacent block rows is different from each other in the tread circumferential direction,
The tread shape is a pentagonal or more polygonal block, the two sides on both sides of the tread circumferential direction are arranged so as to extend in the tread width direction,
Of the two sides, the length of the side of the block when the tire is rotated is a (mm), and the length of the block in the tread circumferential direction is b (mm). when the ratio a / b is Ri 0.5 ultra der,
A pneumatic tire , wherein a ratio e / b is more than 1 and less than or equal to 2.0, where e (mm) is a maximum length in the tread circumferential direction of the polygonal shape of the pentagon or more .   2. The air according to claim 1, wherein the ratio c / b is greater than 0.5 when a length of a side of the block that is depressed when the tire rotates is c (mm). Enter tire. The pentagonal or higher polygonal block has one or more sipes extending in the tread width direction,
3. The pneumatic tire according to claim 1, wherein the sipe is disposed at a position spaced apart by 4.0 mm or more in a tread circumferential direction from a tread circumferential end of the block. The pneumatic tire according to any one of claims 1 to 3 , wherein a connecting portion that connects the blocks in the tread circumferential direction is provided between at least some of the blocks adjacent in the tread circumferential direction. The pneumatic according to claim 4 , wherein the ratio h / H is 10% or more and 70% or less when the height of the block is H (mm) and the height of the connecting portion is h (mm). tire. Side walls on both sides in the tread width direction of the connecting portion are inclined outward from the connecting portion toward the inner side in the tire radial direction from the outer side in the tire radial direction,
The pneumatic tire according to claim 4 or 5 , wherein an inclination angle θ (°) with respect to a tire radial direction of side walls on both sides in the tread width direction of the connecting portion is 0 ° or more and 5 ° or less.

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