JP2018039482A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire having an excellent uneven wear resistance, which can suppress generation of uneven wear in a tread width direction.SOLUTION: A tire has at least one land part, which is partitioned by at least two circumferential grooves which extend in a circumferential direction of a tread, on a tread surface of the tread of the tire. In at least one land part, an angle of a side wall on a tread end side of the land part to a normal line at a boundary with the side wall of the land part surface with the boundary as an apex is -10° or more and 2° or less when a direction inclined to the land part side is so made as to be minus, and a ratio of a tread width direction length of the land part surface to a length of the side wall on the tread end side along the normal line is 1.7 or more and 3.9 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire, in particular, a tire excellent in uneven wear resistance that can suppress the occurrence of uneven wear in the tread width direction.

  Conventionally, various devices have been made to suppress uneven wear of tires. For example, in Patent Document 1, the tread width direction outer wall surface of the second land portion from the outer side in the tread width direction is inclined in the tread width direction from the inner side in the tire radial direction to the outer side. A tire that suppresses uneven wear in the width direction of the tread is described.

  The invention described in Patent Document 1 is based on the knowledge that the wear amount at the outer end portion in the tread width direction of the second land portion from the outer side in the tread width direction is relatively large. By suppressing, uneven wear in the tread width direction is suppressed. This technique can improve uneven wear resistance.

Japanese Patent Application Laid-Open No. 2014-221466

There are various road surface conditions on which the vehicle travels, and the vehicle is not limited to paved roads, and there are many opportunities to travel on unpaved bad roads with severe irregularities. Furthermore, the surface of the paved road is generally inclined from the center of the two lanes to the shoulder of the road, and if the surface is dug and cracks or holes are generated, it may be uneven or uneven. is there. Also, the load applied to the vehicle is various, and the load on the truck and bus is larger than that on the passenger car. In particular, the load on the truck and bus is greatly increased or decreased depending on the loading condition.
Thus, the driving environment and driving conditions of the vehicle are diverse, and therefore the tire supporting the vehicle receives various inputs from the road surface. In particular, uneven wear is likely to occur due to input in the tread width direction, and the tire described in Patent Document 1 described above is effective in suppressing uneven wear with respect to input in the tread width direction when the vehicle is traveling.

However, in recent years, there is a demand for further improving uneven wear resistance. For example, as described above, the traveling environment and traveling conditions of the vehicle are various, and sometimes the tire is used on a rough road surface or the use under a heavy load is continued. Therefore, there is a demand for providing a tire that can further improve uneven wear resistance, and in particular, can reliably suppress uneven wear even under such various usage conditions.
Accordingly, an object of the present invention is to provide a tire that further improves uneven wear resistance.

  The inventors have intensively studied how to reliably suppress the uneven wear of the tire, and when a lateral force is applied to the tire, the difference in deformation amount between the belt side of the tire and the land portion increases, and the uneven wear does not occur. It occurs, especially in radial tires, because the deformation amount of the belt is small, the difference in deformation amount from the land portion is likely to increase.In addition, the land portion is greatly deformed particularly on the side receiving the side force input, It has been found that the difference in deformation from the belt tends to increase. Therefore, in conjunction with the definition of the angle formed by the side wall of the land portion of the tread and the surface of the land portion, the height and width of the land portion are defined under an appropriate ratio. Contributes to restraint, reduces the difference in deformation between the land and belt, and reduces the difference in wear energy on both side walls of the land of the tire, further improving uneven wear resistance in various road conditions and usage environments The tire of the present invention has been completed by newly finding that it is effective for improvement.

The gist of the present invention is as follows.
(1) The tire of the present invention has at least one land portion that is partitioned by at least two circumferential grooves extending in the circumferential direction of the tread on the tread surface of the tire tread, One is that the angle of the side wall on the tread end side of the land portion with respect to the normal to the boundary portion of the surface of the land portion with the side wall is a minus direction in which the angle is inclined toward the land portion side. And the ratio of the length in the tread width direction of the surface of the land portion to the length along the normal line of the side wall on the tread end side is 1.7 to 3. It is 9 or less.
The “land surface” in the present invention refers to the surface excluding the side wall.

According to the tire having such a configuration, it is possible to further suppress uneven wear even in various road surface conditions and use environments.
Furthermore, the effects of suppressing uneven wear can be further improved by the following configurations (2) to (6).

(2) In the tire of the present invention, it is preferable that the angle of the side wall on the tread end side is −6 ° or more and 0 ° or less.
(3) In the tire of the present invention, the length ratio is preferably 2.6 or more and 3.0 or less.
(4) In the tire of the present invention, at least one of the land portions has the boundary portion with respect to a normal line at a boundary portion between the equator side wall of the land portion and the sidewall of the land portion surface. The angle is preferably 6 ° or less.
(5) In the tire according to the present invention, the land portion is preferably a rib.
(6) The tire according to the present invention is a block row in which at least one of the land portions is partitioned by a plurality of widthwise grooves extending in a direction crossing the equator of the tire, and a plurality of blocks are arranged in the tread circumferential direction. The both side walls of the block each form two side walls and two sides facing the width direction groove of the block, and the angles of the two sides with respect to the normal line are different by 3 ° or more. preferable.

  According to the present invention, a tire that can further suppress uneven wear can be provided.

(A) It is a partially expanded sectional view of the tread part periphery of the tire concerning one Embodiment of this invention. (B) It is a partial expansion | deployment top view of the inclination belt layer of Fig.1 (a). It is the elements on larger scale of the land part 4 of FIG. It is a graph which shows the evaluation result of a wear energy difference. It is a graph which shows the evaluation result of a wear energy difference. It is a graph which shows the evaluation result of a wear energy difference. It is a footprint figure of the tire concerning the present invention showing the road surface contact state of a tread. It is a figure which shows a road surface cant. It is a figure which shows the tread surface of the tire concerning another embodiment of this invention. 3 is a three-dimensional perspective view showing a block 11. FIG. (A) And (b) is a figure which shows the end surface 11c and the end surface 11d of the block 11 of FIG.

Hereinafter, the process that led to the tire of the present invention will be described.
In general, the amount of tire wear is proportional to the wear energy, which is the energy caused by friction when the tread surface comes into contact with the road surface. If there is a large difference in wear energy between the side walls of the land, uneven wear occurs. Cheap. Therefore, the inventors first conducted the following experiment in order to examine an appropriate range of the inclination angle of the sidewall of the land portion of the tire.

  The tire targeted in this experiment has a carcass 2 extending in a toroidal shape across a pair of bead cores as a skeleton as shown in FIG. Four inclined belt layers 3a, 3b, 3c and 3d are provided on the outer side in the direction, and the tread 4 is provided on the outer side in the tire radial direction of the inclined belt layers 3a to 3d. Furthermore, the tire 1 in the illustrated example has two center-side land portions 6 which are partitioned by three circumferential grooves 5 extending along the tire circumferential direction on the tread 4 tread surface. The illustrated tire also has two shoulder-side land portions 7 defined by the circumferential groove 5 and the tread end TE.

  Based on the tire structure described above, as shown in FIG. 2, the normal M1 of the side wall 6a on the tread end TE side of the center side land portion 6 at the boundary portion 6c between the surface 6s of the center side land portion 6 and the side wall 6a. In contrast, a large number of tires were manufactured in which the side wall angle α1 having the boundary 6c as the apex was varied in a range of −15 ° to 15 °. At this time, the direction in which the side wall angle α1 is inclined to the land portion side is negative, and the direction in which the side wall angle α1 is inclined to the opposite side to the land portion is positive. Further, the side wall angle β1 having the apex at the boundary 6d with respect to the normal M2 at the boundary 6d between the surface 6s of the center side land 6 and the side wall 6b of the side wall 6b on the equator CL side of the center side land 6 is 0 °.

  These prototype tires are incorporated into a tread observation device described in Japanese Patent Laid-Open No. 2005-265748, the three component forces and the slip amount are measured, the wear energy is calculated based on the three component forces and the slip amount, and the center side land portion The difference in wear energy between the six side walls 6a and 6b was calculated. The evaluation results were evaluated by an index with the side wall angle α1 being −15 ° as a reference 100. When the evaluation result is an index smaller than 100, it indicates that the uneven wear resistance performance is improved. The experimental results are shown in FIG. In the prototype tire, the center-side land portion 6 has a height H1 which is a length W1 in the tread width direction of the surface 6s and a length H1 along the normal M1 of the side wall 6a on the tread end TE side. The ratio of the length W1 in the width direction with respect to was made common with 2.0.

  From the experimental results shown in FIG. 3, it can be seen that when the side wall angle α1 is in the numerical range of −14 ° or more and 2 ° or less, the uneven wear resistance is improved to a wear energy difference of less than 100. Here, when the side wall angle α1 is less than −10 °, when the vulcanized tire is taken out from the vulcanization mold at the time of manufacture, the mold is caught on the corner portion constituted by the surface of the land portion of the tire and the side wall, Detachability of the product tire from the mold will deteriorate. Therefore, it has been found that by setting the side wall angle α1 within a numerical range of −10 ° to 2 °, uneven wear resistance can be improved while maintaining ease of manufacturing.

  Based on the above knowledge, further study was conducted on the influence of the side wall angle α1 on the wear energy difference. Then, even when the side wall angle α1 is in the range of −10 ° to 2 °, there are some cases where the desired wear energy difference 100 is not realized. As a result of further investigation on this cause, even if the side wall angle α1 satisfies the range of −10 ° to 2 °, the case where the wear energy difference is not suppressed to 100 or less is the case of satisfying the case and the width of the land portion. It came to investigate newly that height is different. Therefore, the inventors examined conditions regarding the width and height of the land portion in order to obtain higher uneven wear resistance performance in the above numerical range of the sidewall angle α1 of the land portion of the tire. Then, in addition to defining the side wall angle of the land portion of the tire, defining the height and width of the land portion under an appropriate ratio can further improve uneven wear resistance particularly in various road surface conditions and usage environments. I thought it was effective. The results obtained here will be described in detail below.

Based on the tire structure similar to the prototype tire, the side wall angle α1 of the side wall 6a on the tread end TE side of the center side land portion 6 is set to −10 ° to 2 °, and the center side land portion 6 shown in FIG. Further, a large number of tires were manufactured by variously changing the ratio W1 / H1 of the length W1 in the tire width direction of the top surface to the length H1 along the normal M1 of the side wall 6a on the tread end TE side.
The difference in wear energy between both side walls of the land portion of the prototype tire is calculated by the same method as in the above experiment, and the evaluation results are obtained when the side wall angle α1 is −15 ° and the ratio W1 / H1 is 2.0. The index was evaluated as the standard 100. When the evaluation result is an index smaller than 100, it indicates that the desired uneven wear resistance performance was obtained. The evaluation results are shown in FIG.

As shown in FIG. 4, even when the side wall angle α1 is set to a numerical value range of −10 ° to 2 °, the evaluation result exceeds 100, depending on the ratio W1 / H1 of the center side land portion 6. It was found that the uneven wear resistance was not obtained. That is, according to these experimental results, it can be seen that the desired uneven wear resistance can be reliably obtained when the ratio W1 / H1 is in the range of 1.7 to 3.9.
Thus, the inventors set the side wall angle α1 of the land portion of the tire to −10 ° to 2 ° and the ratio W1 / H1 of the land portion to 1.7 to 3.9. The present invention has been completed by finding that a tire having higher uneven wear resistance can be realized.

  Hereinafter, the tire of the present invention will be described in detail by exemplifying an embodiment thereof with reference to FIG. 1 again.

  As described above, the tire 1 shown in FIG. 1 is partially omitted in illustration, but the carcass 2 extending in a toroidal shape across a pair of bead cores is used as a skeleton, and four layers are formed on the outer side in the tire radial direction of the carcass 2. The inclined belt layers 3a, 3b, 3c and 3d are provided, and the inclined belt layers 3a to 3d have a tread 4 on the outer side in the tire radial direction. In addition, the tire of this invention is not restricted to this, For example, it is also possible to make a belt structure into 3 layers. Furthermore, the tire of the present invention has at least one land portion that is divided by at least two circumferential grooves 5 extending along the circumferential direction of the tread 4 along the circumferential direction of the tire. It is divided into two center side land portions 6 by a circumferential groove 5 of the book. The tire of the present invention also has two shoulder side land portions 7 defined by the circumferential groove 5 and the tread end TE. In addition, the land part of FIG. 1 can also be made into the block divided by a rib or a transverse groove.

  As described above, the side wall angle α1 of the center side land portion 6 is −10 ° to 2 ° and the ratio W1 / H1 of the land portion is 1.7 to 3.9. This is advantageous in reducing the difference in wear energy between the two side walls 6a and 6b.

  In the tire according to the present invention, the side wall angle α1 is not less than −10 ° and not more than 2 ° and the ratio W1 / H1 is not less than 1.7 and not more than 3.9 on only one side of the tread tread with the equator CL as a boundary. When a land portion that satisfies the range is provided, it is preferable that the groove wall having the inclination angle α1 is mounted in a direction that faces the outside of the vehicle. This is because the side force is mainly input from the direction orthogonal to the traveling direction of the normal tire.

In the present invention, the side wall angle α1 of the side wall 6a is more preferably in the range of −6 ° to 0 °.
This is because when the side wall angle α1 is defined within the above numerical range, it is possible to improve uneven wear resistance.

In the present invention, the ratio W1 / H1 of the center side land portion 6 is more preferably 2.6 or more and 3.0 or less.
This is because the uneven wear of the center side land portion 6 can be further suppressed by setting the above numerical range.
The width direction length W1 is preferably 20 mm or more and 50 mm or less, and the height H1 is preferably 5 mm or more and 20 mm or less.

  Furthermore, in the tire according to the present invention, at least one of the center side land portions 6 is a boundary portion 6d between the surface 6s of the center side land portion 6 and the side wall 6b of the side wall 6b on the equator CL side of the center side land portion 6. It is preferable that the side wall angle β1 with the boundary portion 6d as the apex with respect to the normal line M2 in FIG. More preferably, it is 5 ° or less.

  Based on the tire structure shown in FIG. 1, a large number of tires were manufactured in which the side wall angle 6b on the equator CL side of the center side land portion 6 was variously changed within the range of −15 ° to 15 °. At this time, the direction in which the side wall angle β1 is inclined toward the land portion is negative, and the direction where the sidewall angle β1 is inclined toward the opposite side to the land portion is positive. Further, the side wall angle α1 of the center side land portion 6 is set to 0 °.

The difference in wear energy between both side walls of the land portion of the prototype tire is calculated by the same method as the above experiment, and the evaluation results are obtained when the side wall angle β1 is −15 ° and the ratio W1 / H1 is 2.0. The index was evaluated as the standard 100. When the evaluation result is an index smaller than 100, it indicates that the desired uneven wear resistance performance was obtained. The evaluation results are shown in FIG.
In the prototype tire, the ratio W1 / H1 of the center side land portion 6 was made common with 2.0.

In the present invention, as shown in FIG. 2, the side wall 7a on the tread end TE side of the shoulder side land portion 7 with respect to the normal line N1 at the boundary portion 7c between the surface 7s of the shoulder side land portion 7 and the side wall 7a, It is preferable that the side wall angle γ1 having the boundary portion 7c as the apex is −15 ° or more. At this time, the direction in which the side wall angle γ1 is inclined to the land portion side is negative, and the direction in which the side wall angle γ1 is inclined to the opposite side to the land portion is positive. When the angle is less than −15 °, the compression rigidity is lowered, the deformation of the land portion under load is increased, and the movement of the land portion is also increased. The side wall angle δ1 having the boundary portion 7d as the apex with respect to the normal line N2 at the boundary portion 7d between the surface 7s and the side wall 7b of the shoulder side land portion 7 of the side wall 7b on the equator CL side of the shoulder side land portion 7 is −8. It is preferable to set it to at least 1 ° and at most 1 °.
Moreover, the tire width direction length W2 of the top surface with respect to the length H2 along the normal line N2 of the side wall 7b on the equator CL side of the shoulder side land portion 7 can be set to 4.6, for example. Furthermore, the width direction length W2 is preferably 20 mm or more and 50 mm or less, and the height H2 is preferably 5 mm or more and 20 mm or less.

  In the present invention, as shown in FIG. 1A, the inclined belt layer 3a is disposed on the inner side in the tire radial direction of the two center-side land portions 6, and the inclined belt layers 3b, 3c, and 3d are arranged on the two center sides. It is preferable to arrange in the tire radial direction inner side of the land part 6 and the shoulder side land part 7.

  Regarding the inclined belt layer 3b of the present invention, the shortest distance L1 between the inclined belt layer 3b and the tread surface, the surface 6s of the center side land portion 6 and the side wall 6a of the side wall 6a on the tread end TE side of the center side land portion 6 The shortest distance L2 from the boundary portion 6c is preferably 11 mm or more and 27 mm or less. The inclined belt layer 3b is the belt layer that exerts the most tension when the side force acts on the tire. By keeping the distance from the tread surface, the inclined belt layer 3b can suppress relative deformation of the belt with the tread surface. it can. On the other hand, if it exceeds 27 mm, the compression rigidity is lowered, and there is a possibility that the deformation of the belt layer when the tire is loaded becomes too large.

  In the present invention, as shown in FIG. 1B, the inclination angle θ1 with respect to the tread width direction of the cord constituting the inclined belt layer 3a can be set to 40 °, for example, and the inclined belt layer 3b Is preferably 60 ° or more with respect to the tread width direction of the cord constituting the cord. Further, the cord constituting the inclined belt layer 3c is configured such that the inclination direction is opposite to that of the cords 3a and 3b with respect to the tread width direction, and θ3 thereof may be 60 ° or more with respect to the tread width direction. preferable. The inclination of the cord constituting the inclined belt layer 3d with respect to the tread width direction is inclined in the same direction as 3c, and θ4 thereof can be set to 74 °, for example. In the above configuration, by setting θ2 and θ3 to 60 ° or more, the relative displacement between the belt layer and the land portion can be suppressed.

FIG. 6 is a footprint diagram of the tire according to the present invention showing the road surface contact state of the tread. Attach the tire to the applicable rim, set the specified air pressure, place it perpendicular to the flat plate in a stationary state, and apply the contours of the four land parts on the contact surface with the flat plate when a load is applied to the specified mass. In the circumferential groove 5, let F be a series of contour lines that follow the contour lines of the land portions on both sides. When the circumferential length Fl1 of a line connecting two points where the contour line F and the equator CL intersect is 100, the extension line of the boundary portion 6d located on the equator CL side of the center side land portion 6 and the contour line F are The ratio of the circumferential length Fl3 connecting the two points where the extension line of the boundary portion 6c located on the tread end side of the center side land portion 6 and the contour line F to the circumferential length Fl2 connecting the two intersecting points is as follows: It is preferably 90% or more. This is to suppress drag wear in the tread circumferential direction.
Furthermore, when the maximum linear distance in the tire width direction closest to the tread edge TE from the equator CL on the contact surface is Fw1, and the shortest distance from the equator CL to the boundary 6c of the center side land portion 6 is Fw2, the distance Fw2 Is preferably 30% or more and 65% or less of the distance Fw1.
This is because if this ratio is less than 30%, drag wear occurs on the land. On the other hand, if the ratio is more than 65%, the deformation of the land portion due to the side force becomes large.

By the way, in order to improve the drainage of the road surface, on the road surface provided with a so-called cross slope (road surface cant) from the central separation zone of the road surface to each end of the both roads, the center of the road is higher than the both ends of the road. It has become. Here, as shown in FIGS. 7A and 7B, the road surface cant generally inclines to the left in the case of left-hand traffic and to the right in the case of right-hand traffic. FIG. 7A shows a road surface cant for left-hand traffic, and FIG. 7B shows a road surface cant for right-hand traffic. Therefore, when the vehicle travels straight on a straight road, the tire tends to receive a side force from the direction in which the road surface cant descends to the direction in which the slope climbs. For example, in the case of left-hand traffic (FIG. 7A), both the left wheel and the right wheel mounted on the vehicle receive a side force caused by a road surface cant from the left side.
In the tire of the present invention, a plurality of land portions are provided on the tread tread surface 4, and only one of the center side land portions 6 has a side wall angle α1 of −10 ° to 2 ° and a ratio W1 / H1 of 1.7. When the numerical range of 3.9 or less is satisfied, the center side land portion 6 is arranged on the left side in the traveling direction in the left-hand traffic, and on the right side in the traveling direction in the right-hand traffic. Thus, it is preferable that both wheels are mounted. This is because the input due to the road surface cant, that is, the side force is maximized at the position. In the example shown in FIGS. 7A and 7B, the land portions other than the center side land portion 6 do not satisfy the requirements of the angle α1 and the ratio W1 / H1 of the present invention. It is preferable to carry out the wheel mounting in the arrangement as described above. When the other land portions together with the center side land portion 6 satisfy the regulations of the side wall angle α1 and the ratio W1 / H1, it is not necessary to specifically limit the mounting.

Subsequently, a tire according to a second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a development view showing a tread surface of a tire according to another embodiment of the present invention.
The tire 1 shown in FIG. 8 has a carcass 2 extending in a toroidal shape across a pair of bead cores as a skeleton, as in the embodiment shown in FIG. Four inclined belt layers are provided, and the inclined belt layer 3 has a tread 4 on the outer side in the tire radial direction.

In the present invention, as shown in FIG. 8, the tread surface of the tread 4 of the tire 1 is partitioned into a plurality of land portions 9 by a plurality of circumferential grooves 8, and at least one of the land portions 9 has a plurality of widths. The directional groove 10 is divided into a plurality of blocks 11. A three-dimensional perspective view of the block 11 is shown in FIG. In addition, the block 11 arrange | positioned continuously in the circumferential direction has the same shape.
The block 11 has a plurality of circumferential grooves 8 or two circumferential end faces 11a and 11b adjacent to the tread end TE, and the circumferential both end faces 11a and 11b each have two circumferential faces 10 facing each other. The end faces 11c and 11d in the width direction and the sides 12, 13, 14, and 15 are formed. FIG. 10A is a diagram showing the end surface 11c of the block 11, and FIG. 10B is a diagram of the end surface 11d viewed from the end surface 11c side. In the illustrated example, the end surface 11 c has a side 12 and a side 13, and the end surface 11 d has a side 14 and a side 15. The side wall angle α2 with respect to the normal M3 of the side 12 on the end face 11c is preferably 3 ° or more larger than the side wall angle α3 with respect to the normal M5 of the side 14 on the end face 11d. Furthermore, the side wall angle β2 with respect to the normal M4 of the side 13 on the end face 11c is preferably 3 ° or more larger than the side wall angle β3 with respect to the normal M6 of the side 15 on the end face 11d.
According to the said structure, the land part shear force of kicking out can be reduced further by changing the side wall angle of a block from the treading side of a tire to the kicking out side.
Furthermore, the tire according to the present embodiment can improve the uneven wear resistance more effectively by specifying the rotation direction.

Examples of the present invention will be described below, but the present invention is not limited thereto.
Invention tires and comparative tires (both tire sizes are 10.00R20) were prototyped according to the specifications shown in Table 1, and the uneven wear resistance of the tires was evaluated.

Each test tire is assembled to an applicable rim (7.5V × 20), filled with an internal pressure of 800 kPa, and a tire loaded with a load of 29.8 kN is run at a speed of 60 km / h on a test drum that can simulate the form of wear on the market. It was.
The evaluation of uneven wear resistance of the tire was made by calculating the amount of tread wear during running at 10,000 km from the tire surface shape.

  The results in Table 1 are shown as an index with the result of Comparative Example Tire 1 being 100. Regarding the uneven wear resistance of the tire, the larger the index, the better the performance.

1 ·· Tire, 2 · · Carcass · 3 · 3a ~ 3b · · Inclined belt layer · 4 · · Tread · 5 · · Circumferential groove · 6 · · Land on the center side · 6s · · · surface · 6a · 6b · · Side walls, 6c, 6d · · Border, 7 · · Shoulder side land, 7s · · Surface, 7a, 7b · · Side walls, 7c, 7d · · Border, 8 · · Circumferential groove, · · · Land Part, 10 .... width direction groove, 11 .... block, 11a, 11b, 11c, 11d ... end face, 12, 13, 14, 15 ... side

Claims (6)

The tread surface of the tire has at least one land portion defined by at least two circumferential grooves extending in the circumferential direction of the tread;
At least one of the land portions is such that an angle of the side wall on the tread end side of the land portion with respect to a normal line at a boundary portion between the land surface and the side wall is a vertex on the land portion side. When the inclination direction is negative, it is −10 ° to 2 °, and the ratio of the length in the tread width direction of the land surface to the length along the normal line of the side wall on the tread end side is 1 The tire is characterized by being 7 or more and 3.9 or less.   The tire according to claim 1, wherein the angle of the side wall on the tread end side is -6 ° or more and 0 ° or less.   The tire according to claim 1 or 2, wherein the length ratio is 2.6 or more and 3.0 or less.   At least one of the land portions has an angle of 6 ° or less with the boundary portion as a vertex of the normal line at the boundary portion of the land portion with the side wall on the equator side wall of the land portion. The tire according to any one of claims 1 to 3, wherein   The tire according to claim 1, wherein the land portion is a rib. At least one of the land portions is a block row that is partitioned by a plurality of widthwise grooves extending in a direction crossing the equator of the tire, and a plurality of blocks are arranged in the tread circumferential direction.
The both side walls of the block each form two side walls and two sides facing the width direction groove of the block, and the angles of the two sides with respect to the normal line differ by 3 ° or more. The tire according to claim 1, characterized in that it is characterized.

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