JP2022016018A - Tire for off-road traveling - Google Patents

Abstract

To provide an off-road traveling tire capable of improving performances of uneven wear resistance and breakage resistance of a block formed at the end side of tread.SOLUTION: The main grooves 4A, 4B of an off-road traveling tire include a first main groove 4A disposed at a position nearest to a first tread end E1 and a second main groove 4B adjacent to the first main groove 4A, and mutual zigzag phases are aligned. The first and second main grooves include a first apex 7 protruding at the first tread end side, and a second apex 8 protruding at a second tread end E2 side. The land parts 5A, 5B include a first land part 5A between the first tread end and the first main groove, and a second land part 5B between the first and the second main grooves. The first land part 5A comprises a plurality of the first blocks 11 equipped with a taper-like part 15 whose circumferential length decreases toward the second tread end side. The second land part 5B comprises a plurality of second blocks 12 separated by a groove-like element 18, and the first end part of the first tread end side in the groove-like element communicates with the position other than the second apex of the first main groove.SELECTED DRAWING: Figure 2

Description

The present invention relates to a tire for traveling on rough terrain.

Patent Document 1 describes a pneumatic tire for traveling on rough terrain. In the tread portion of this pneumatic tire, a plurality of inclined grooves inclined to one side with respect to the tire axial direction and a plurality of inclined grooves adjacent to each other in the tire circumferential direction are connected and arranged in the tire axial direction. A joint groove is provided. As a result, a plurality of blocks are arranged along the inclined grooves between the inclined grooves of the pneumatic tire. Further, a substantially trapezoidal block is arranged along the grounding end.

Japanese Patent No. 5981959

The substantially trapezoidal block of the pneumatic tire has a problem that uneven wear and chipping are likely to occur.

The present invention has been devised in view of the above circumstances, and is a tire for running on rough terrain that can improve the uneven wear resistance and the block chipping resistance of the block formed on the tread end side. The main purpose is to provide.

The present invention is a tire for running on rough terrain having a tread portion defined by a first tread end and a second tread end, and the tread portion is a plurality of tires that continuously extend in a zigzag shape in the tire circumferential direction. The main groove includes a main groove and a plurality of land portions separated by the main groove, and the main groove is adjacent to the first main groove arranged closest to the first tread end and the first main groove. The first main groove and the second main groove are aligned with each other in a zigzag phase, including the second main groove, and the first main groove and the second main groove are on the end side of the first tread. The land portion includes a first top portion that is convex to the surface and a second top portion that is convex to the end side of the second tread, and the land portion is a first land portion between the first tread end and the first main groove. And a second land portion between the first main groove and the second main groove, the first land portion is composed of a plurality of first blocks, and each of the first blocks is the first block. The second land portion is provided with a tapered portion whose length decreases in the tire circumferential direction toward the end side of the tread, and the second land portion is composed of a plurality of second blocks separated by a groove-shaped element. The first end portion on the end side of the first tread communicates with a position other than the second top portion of the first main groove.

In the tire for traveling on rough terrain according to the present invention, the first end portion is located on the second top portion side between the first top portion and the second top portion of the first main groove. May be good.

In the tire for traveling on rough terrain according to the present invention, the first end portion may be located within a region having a radius of 4 to 16 mm centered on the second top portion.

In the tire for traveling on rough terrain according to the present invention, the angle between the groove center line of the groove-shaped element and the groove center line of the first main groove at the first end is 90 to 110 °. There may be.

In the tire for traveling on rough terrain according to the present invention, the second end portion of the groove-shaped element on the second tread end side is located between the first top portion and the second top portion of the second main groove. The angle between the groove center line of the groove-shaped element and the groove center line of the second main groove at the second end portion may be 70 to 90 °.

In the tire for traveling on rough terrain according to the present invention, the second block includes at least one circumferential edge extending in the circumferential direction of the tire on the first main groove side, and is in the tire circumferential direction of the circumferential edge. The length may be 15% to 25% of the length in the tire circumferential direction of the second block.

In the tire for running on rough terrain according to the present invention, the second block has a first portion inclined in the first direction with respect to the tire axial direction and a side opposite to the first direction with respect to the tire axial direction. It may include a second portion inclined in the second direction which is the direction of.

In the tire for traveling on rough terrain according to the present invention, the main groove further includes a third main groove adjacent to the second main groove, and the third main groove includes the first main groove and the second main groove. The main groove and the zigzag phase of each other are aligned, the land portion further includes a third land portion between the second main groove and the third main groove, and the third land portion is a groove. It is composed of a plurality of third blocks separated by a shape element, and the first end portion of the groove shape element on the first tread end side communicates with a position other than the second top portion of the second main groove. May be good.

In the tire for traveling on rough terrain according to the present invention, the third block includes at least one circumferential edge extending in the circumferential direction of the tire on the second main groove side, and is in the tire circumferential direction of the circumferential edge. The length may be 5% to 15% of the length in the tire circumferential direction of the third block.

In the tire for running on rough terrain according to the present invention, the ratio Ea / Eb of the edge component Ea in the tire axial direction of the first block and the edge component Eb in the tire circumferential direction is the tire axial direction of the third block. The ratio Ec / Ed of the edge component Ec and the edge component Ed in the tire circumferential direction may be 85% to 95%.

In the tire for running on rough terrain according to the present invention, the ratio Ee / Ef of the edge component Ee in the tire axial direction of the second block and the edge component Ef in the tire circumferential direction is the tire axial direction of the third block. The ratio Ec / Ed of the edge component Ec and the edge component Ed in the tire circumferential direction may be 80% to 90%.

In the tire for traveling on rough terrain according to the present invention, the groove-shaped element may be a sipe having a width of 1.5 mm or less.

In the tire for traveling on rough terrain according to the present invention, the groove-shaped element may be a groove having a width larger than 1.5 mm.

In the tire for traveling on rough terrain according to the present invention, the land ratio of the tread portion may be 60% to 75%.

By adopting the above configuration, the tire for traveling on rough terrain of the present invention can improve the uneven wear resistance and the block chipping resistance of the block formed on the tread end side.

It is a development view which shows an example of the tread part of the tire for rough terrain running. It is a partially enlarged view of the 1st land part and the 2nd land part of FIG. It is an enlarged view of FIG. It is a partially enlarged view of the 3rd land part and the 4th land part. It is a partially enlarged view explaining the edge component of the 3rd block. It is a development view which shows an example of the tread part of the tire for running on the rough terrain of another embodiment of this invention. It is a development view of the tread part of the comparative example 1. FIG. It is a development view of the tread part of the comparative example 2. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are used for the purpose of exemplifying and explaining the present invention, and the present invention is not construed as being limited to the specific forms shown in the drawings.

[Tire for running on rough terrain (first embodiment)]
FIG. 1 is a developed view showing an example of a tread portion 2 of a tire 1 for traveling on rough terrain. The tire 1 of the present embodiment is used for high-speed traveling on rough terrain such as a dirt trial and a rally. Although the internal structure of the tire 1 is not shown in FIG. 1, the tire 1 of the present embodiment may adopt, for example, a radial structure having high tread rigidity.

[Tread part]
The tread portion 2 of the present embodiment is defined by a first tread end E1 and a second tread end E2. In the present specification, the first tread end E1 and the second tread end E2 are defined as positions on the outermost side of the tread contact patch in the tire axial direction under a normal load condition.

The "normal load load state" means a state in which a normal load is applied to a tire 1 in a normal state assembled on a normal rim with a normal internal pressure and the tire 1 is grounded on a flat surface at a camber angle of 0 degrees. Unless otherwise specified, the dimensions and the like of each part of the tire 1 are values measured in the "normal state".

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. Therefore, the regular rim is, for example, "standard rim" for JATMA, "Design Rim" for TRA, and "Measuring Rim" for ETRTO.

The "regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. Therefore, for example, the normal internal pressure is "maximum air pressure" for JATTA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO.

The "regular load" is a load defined for each tire in the standard system including the standard on which the tire is based. Therefore, the normal load is, for example, "maximum load capacity" for JATTA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO.

The tread portion 2 of the present embodiment is a first tread pattern portion 3A arranged between the first tread end E1 and the tire equator C, and a second tread portion 2 arranged between the second tread end E2 and the tire equator C. 2 Tread pattern portion 3B is included. In the present embodiment, the first tread pattern portion 3A and the second tread pattern portion 3B are line-symmetrical with respect to the tire equatorial line C so as to be displaced from each other in the tire circumferential direction (that is, phase-shifted in the tire circumferential direction). Have a relationship of.

The tread portion 2 is configured to include a plurality of main grooves 4 extending continuously in a zigzag shape in the tire circumferential direction, and a plurality of land portions 5 separated by these main grooves 4. In FIG. 1, in order to help understanding, four typical main grooves 4 are lightly colored in the first tread pattern portion 3A.

[1st tread pattern part]
[Main groove]
The main groove 4 includes a first main groove 4A arranged closest to the first tread end E1 and a second main groove 4B adjacent to the first main groove 4A. Further, the main groove 4 of the present embodiment further includes a third main groove 4C adjacent to the second main groove 4B and a fourth main groove 4D adjacent to the third main groove 4C. The main groove 4 is not limited to such an embodiment, and for example, the third main groove 4C and the fourth main groove 4D may be omitted.

Each main groove 4 (in this example, the first main groove 4A to the fourth main groove 4D) has a first top portion 7 that is convex toward the first tread end E1 side and a first portion that is convex toward the second tread end E2 side. It is configured to include two tops 8. The first top 7 and the second top 8 are alternately arranged in the tire circumferential direction.

Further, each main groove 4 includes a first inclined element 9 inclined in the first direction and a second inclined element 10 inclined in the second direction. These first inclined elements 9 and the second inclined elements 10 are arranged alternately in the tire circumferential direction. The first direction is a direction inclined with respect to the tire axial direction. On the other hand, the second direction is a direction that is inclined to the side opposite to the first direction with respect to the tire axial direction. In FIG. 1, the mode in which the first direction is downward to the right and the second direction is upward to the right is shown.

In the present embodiment, the first top portion 7 and the second top portion 8 have a circumferential edge extending in the tire circumferential direction (the circumferential edge 16 shown in FIG. 2) between the first inclined element 9 and the second inclined element 10. , 17, etc.). The first top portion 7 and the second top portion 8 are not limited to the mode composed of the circumferential edge, for example, at the intersection of the first inclined element 9 and the second inclined element 10 (not shown). It may be configured. Each first top portion 7 of the first main groove 4A of the present embodiment communicates with the first tread end E1.

Each main groove 4 (in this example, the first main groove 4A to the fourth main groove 4D) has a zigzag shape having a total amplitude A in the tire axial direction and a period P in the tire circumferential direction. There is. The total amplitude A is the distance in the tire axial direction from the first top portion 7 to the second top portion 8 of the main groove 4. In the present embodiment, the zigzag waveforms of the main grooves 4 are all the same.

The main grooves 4 (in this example, the first main groove 4A to the fourth main groove 4D) are arranged in a zigzag phase with each other. That is, the first top portion 7 and the second top portion 8 of each main groove 4 both appear at the same position in the tire circumferential direction. The plurality of main grooves 4 having such zigzag phases aligned generate frictional force in the tire circumferential direction and the tire axial direction in a well-balanced manner on a hard dirt road, and thus exhibit excellent traction and lateral grip. be able to.

In order to further enhance the above-mentioned action, the first inclined element 9 and the second inclined element 10 are, for example, 30 to 60 degrees, preferably 35 to 55 degrees, more preferably 40 to 50 degrees with respect to the tire axial direction. It is desirable to incline at the angle θ1 of. Further, it is desirable that the groove width W1 of each main groove 4 is in the range of, for example, 4.5 to 8.5 mm. The groove width W1 is measured in a direction orthogonal to the longitudinal direction of the measurement portion.

[Land]
The land portion 5 includes a first land portion 5A between the first tread end E1 and the first main groove 4A, and a second land portion 5B between the first main groove 4A and the second main groove 4B. It is composed of. Further, in the land portion 5 of the present embodiment, the third land portion 5C between the second main groove 4B and the third main groove 4C and the third land portion 5C between the third main groove 4C and the fourth main groove 4D are provided. 4 land 5D and so on are included. The land portion 5 is not limited to such an embodiment, and for example, the third land portion 5C and the fourth land portion 5D may be omitted.

[1st land area]
FIG. 2 is a partially enlarged view of the first land portion 5A and the second land portion 5B of FIG. The first land portion 5A is composed of a plurality of first blocks 11. Each first block 11 is divided into a first inclined element 9 and a second inclined element 10 adjacent to each other in the tire circumferential direction in the first main groove 4A, and a first tread end E1. Due to the first inclined element 9 and the second inclined element 10, each of the first blocks 11 has a tapered portion whose length in the tire circumferential direction decreases toward the second tread end E2 (shown in FIG. 1). It is equipped with fifteen.

The tapered portion 15 allows the first block 11 to provide edges having different orientations on the first tread end E1 side in a well-balanced manner. Therefore, the first block 11 can exhibit excellent traction and lateral grip on a hard dirt road.

The first block 11 of the present embodiment has a circumferential edge 16 extending in the tire circumferential direction at the tip end portion of the tapered portion 15 on the second tread end E2 side (second top 8 side). As a result, the contour shape of the tread surface of the first block 11 is formed into a trapezoidal shape. With such a circumferential edge 16, the first block 11 can secure the block rigidity of the tip portion thereof, and can improve the uneven wear resistance and the block chipping resistance.

[Second land area]
The second land portion 5B is composed of a plurality of second blocks 12 separated by a groove-shaped element 18. The second land portion 5B of the present embodiment is provided with only the groove-shaped element 18 as a groove completely crossing the second land portion 5B. The groove-shaped element 18 of the present embodiment is inclined in the first direction (downward to the right in the figure) with respect to the tire axial direction. FIG. 3 is an enlarged view of FIG. 2.

As shown in FIG. 3, the first end portion 18a on the first tread end E1 side of the groove-shaped element 18 communicates with a position other than the second top portion 8 of the first main groove 4A. That is, the first end portion 18a of the present embodiment does not communicate with the circumferential edge 17 constituting the second top portion 8, and constitutes the first inclined element 9 or the second inclined element 10 of the first main groove 4A. It communicates with the inclined edge 4As on the E2 side of the second tread end. The first end portion 18a of the present embodiment is specified by the intersection of the groove center line 18c of the groove-shaped element 18 and the inclined edge 4As on the second tread end E2 side of the first main groove 4A.

In this way, the first end portion 18a of the groove-shaped element 18 communicates with a position other than the second top portion 8 of the first main groove 4A, so that the tip end portion (peripheral direction edge) of the tapered portion 15 of the first block 11 is communicated. Regarding 16), the inside in the tire axial direction (second tread end E2 side) is covered with the second block 12. As a result, the tire 1 of the present embodiment prevents a portion where the rigidity is locally reduced from being formed inside the tip portion (in this example, the circumferential edge 16) of the tapered portion 15 in the tire axial direction. Therefore, it is possible to reduce slippage on the road surface in that portion. Therefore, the tire 1 of the present embodiment has traction while preventing uneven wear and chipping that are likely to occur at the tip of the tapered portion 15 with respect to the first block 11 on the first tread end E1 side where slippage during turning becomes large. And lateral grip can be demonstrated.

In the present embodiment, of the outer ends 12a and 12b of the second block 12 in the tire circumferential direction shown in FIG. 2, the first outer end 12a formed on the first main groove 4A side is outside the tire axial direction (outside the tire axial direction). The first tread end (E1 side) is covered by the first block 11. As a result, it is possible to prevent a portion where the rigidity is locally reduced from being formed on the outer side of the first outer end 12a in the tire axial direction, and thus it is likely to occur at the first outer end 12a where the rigidity is relatively small. It can exert traction and lateral grip while preventing uneven wear and chipping.

As shown in FIG. 3, the first end portion 18a of the groove-shaped element 18 is located on the second top portion 8 side between the first top portion 7 and the second top portion 8 of the first main groove 4A. Is desirable. By locating the first end portion 18a on the second top portion 8 side in this way, the first outer end 12a of the second block 12 (1st outer end portion 12a) is located on the first tread end E1 side where the input in the tire axial direction during turning is large. (Shown in FIG. 2) can be prevented from being arranged. As a result, the tire 1 can prevent uneven wear and chipping of the second block 12 together with the first block 11.

In order to exert the above action more, the first end portion 18a of the groove-shaped element 18 is located in the region T1 having a radius R1 centered on the second top portion 8 of the first main groove 4A and having a radius R1 of 4 to 16 mm. It is desirable to have. That is, it is desirable that the distance (radius R1) between the first end portion 18a and the second top portion 8 is 4 to 16 mm. When the second apex 8 is composed of the circumferential edge 16 as in the present embodiment, the center of the region T1 (that is, the second apex 8) is the first inclined element 9 of the first main groove 4A. And it can be specified by the intersection on the extension line of the inclined edges 4At and 4At constituting the second inclined element 10.

Since the first end portion 18a is located in the region T1 having a radius R1 centered on the second top portion 8 and having a radius R1 of 4 mm or more, the first end portion 18a can be displaced from the second top portion 8, so that the first block It is possible to effectively prevent uneven wear and chipping of 11. On the other hand, by locating the first end portion 18a within the region T1 having a radius R1 centered on the second top portion 8 and having a radius R1 of 16 mm or less, the first outer end 12a (shown in FIG. 2) of the second block 12 is formed. It is possible to prevent the input in the tire axial direction during turning from being arranged on the first tread end E1 side where the input is large. As a result, uneven wear or chipping of the second block 12 can be effectively prevented. From such a viewpoint, the first end portion 18a is preferably located within the region T1 having a radius R1 centered on the second top portion 8 and having a radius R1 of 8 mm or more, and preferably the second top portion 8. It is desirable that the center radius R1 is located in the region T1 having a radius of 12 mm or less.

As shown in FIG. 2, in the first end portion 18a (shown in FIG. 3) of the groove-shaped element 18, the groove center line 18c of the groove-shaped element 18 and the groove center line 4A of the first main groove 4A form. The angle (angle of the first outer end 12a of the second block 12) θ2 is preferably 90 to 110 °. By setting the angle θ2 to 90 ° or more, the rigidity of the second block 12 at the first outer end 12a can be maintained, and uneven wear or chipping of the second block 12 can be effectively prevented. can. On the other hand, by setting the angle θ2 to 110 ° or less, it is possible to provide edges having different orientations in a well-balanced manner in the vicinity of the first outer end 12a of the second block 12, and excellent traction on a hard dirt road. And can exert a lateral grip. From such a viewpoint, the angle θ2 is preferably 95 ° or more, and preferably 105 ° or less.

As shown in FIG. 3, the second end portion 18b on the second tread end E2 (shown in FIG. 1) side of the groove-shaped element 18 of the present embodiment is the first top portion 7 and the second portion of the second main groove 4B. It communicates with the top 8 (shown in FIG. 2). As a result, the circumferential edge 27 of the third block 13, which will be described later, is covered with the second block 12. Therefore, since it is possible to prevent a portion where the rigidity is locally reduced from being formed on the outer side of the circumferential edge 27 in the tire axial direction, it is possible to reduce slippage on the road surface at that portion. As a result, the tire 1 of the present embodiment can prevent uneven wear and chipping that are likely to occur at the circumferential edge 27 of the third block 13, and can improve uneven wear resistance and block chipping resistance.

As shown in FIG. 2, in the second end portion 18b (shown in FIG. 3) of the groove-shaped element 18, the groove center line 18c of the groove-shaped element 18 and the groove center line 4Bc of the second main groove 4B form. The angle (angle of the second outer end 12b of the second block 12) θ3 is preferably 70 to 90 °. By setting the angle θ3 to 70 ° or more, the rigidity of the second block 12 at the second outer end 12b can be maintained, so that uneven wear or chipping of the second block 12 can be effectively prevented. Can be done. On the other hand, by setting the angle θ3 to 90 ° or less, it is possible to provide edges having different orientations in a well-balanced manner in the vicinity of the second outer end 12b of the second block 12, and excellent traction on a hard dirt road. And can exert a lateral grip. From such a viewpoint, the angle θ3 is preferably 75 ° or more, and preferably 85 ° or less.

The groove-shaped element 18 of the present embodiment is configured as a sipe having a width W2 (shown in FIG. 1) of 1.5 mm or less. Since such a groove-shaped element 18 can prevent a portion of the second land portion 5B where the rigidity is locally reduced from being continuously formed in the tire axial direction, the uneven wear resistance and the resistance to uneven wear can be prevented. The block chipping performance can be improved. Further, the groove-shaped element 18 can increase the tire circumferential rigidity of the second land portion 5B, which is useful for exhibiting high traction. The groove-shaped element 18 preferably has a width W2 of 0.5 mm or more in order to maintain wet performance.

Each of the second blocks 12 is arranged so as to overlap each of the first blocks 11 in the tire circumferential direction. As a result, the tire 1 can suppress the formation of locally low-rigidity portions that are continuous in a straight line through the main groove 3, so that the tire 1 has improved traction and lateral grip, and has uneven wear resistance and resistance to uneven wear. The block chipping performance can be improved.

The second block 12 has a first portion 21 inclined in the first direction (downward to the right in the figure) with respect to the tire axial direction, and a second portion 21 in a direction opposite to the first direction with respect to the tire axial direction. It is configured to include a second portion 22 inclined in a direction (upward to the right in the figure).

In the second block 12 of the present embodiment, the second portions 22 and 22 are connected to both ends of one first portion 21 in the tire circumferential direction, respectively. As a result, the second block 12 is configured as a zigzag (Z-shaped) block and has high torsional rigidity. Further, the first portion 21 of the present embodiment is formed longer in the tire circumferential direction than the second portions 22 and 22, and can exhibit a large tire circumferential rigidity. Therefore, the second block 12 can improve the uneven wear resistance and the block chipping resistance.

The second block 12 includes at least one circumferential edge 23 extending in the tire circumferential direction on the first main groove 4A side. Such a circumferential edge 23 can provide an edge component in the tire circumferential direction, especially on a hard dirt road, and can enhance lateral grip. Further, since the circumferential edge 23 can increase the rigidity of the second block 12, it is possible to improve the uneven wear resistance and the block chipping resistance.

The circumferential edge 23 of the present embodiment is provided on the first top portion 7 of the first main groove 4A. Such a circumferential edge 23 can increase the rigidity of the second block 12 while providing an edge component in the tire circumferential direction on the first tread end E1 side where the contact pressure becomes large during turning. Therefore, the circumferential edge 23 can effectively improve the lateral grip and improve the uneven wear resistance and the block chipping resistance.

In order to further exert the above action, the tire circumferential length L1 of the circumferential edge (in this example, the circumferential edge provided on the first top portion 7) 23 of the second block 12 is the second block 12. It is desirable to set it to 15% to 25% of the length L2 in the tire circumferential direction. By setting the length L1 of the circumferential edge 23 to 15% or more of the length L2 of the second block 12, it is possible to improve the uneven wear resistance and the block chipping resistance while improving the lateral grip. On the other hand, by setting the length L1 of the circumferential edge 23 to 25% or less of the length L2 of the second block 12, it is possible to prevent the traction during straight running from being lowered. From such a viewpoint, the length L1 of the circumferential edge 23 is preferably 18% or more, preferably 22% or less of the length L2 of the second block 12.

[Third land area]
FIG. 4 is a partially enlarged view of the third land portion 5C and the fourth land portion 5D. The third land portion 5C is composed of a plurality of third blocks 13 separated by a groove-shaped element 19. The third land portion 5C of the present embodiment is provided with only a groove-shaped element 19 as a groove completely crossing the third land portion 5C.

The groove-shaped element 19 of the present embodiment is inclined in the second direction (upward to the right in the figure) with respect to the tire axial direction. Therefore, the groove-shaped element 19 is inclined in the direction opposite to the tire axial direction with the groove-shaped element 18 (shown in FIG. 2) of the second land portion 5B.

The first end portion 19a on the first tread end E1 side of the groove-shaped element 19 communicates with a position other than the second top portion 8 of the second main groove 4B. That is, the first end portion 19a of the present embodiment does not communicate with the circumferential edge 24 constituting the second top portion 8. As a result, with respect to the circumferential edge 23 of the second block 12 provided on the second top 8 of the second main groove 4B, the inside in the tire axial direction (second tread end E2 side) is covered by the third block 13. Will be. Therefore, it is possible to prevent the formation of a portion where the rigidity is locally reduced on the inner side in the tire axial direction (second tread end E2 side) of the circumferential edge 23, thereby reducing slippage on the road surface at that portion. can. As a result, the tire 1 of the present embodiment can exhibit traction and lateral grip while preventing uneven wear and chipping in the vicinity of the circumferential edge 23 of the second block 12.

In the present embodiment, of the outer ends 13a and 13b of the third block 13 in the tire circumferential direction, the first outer end 13a formed on the second main groove 4B side is outside the tire axial direction (first tread end). The E1 side) is covered by the second block 12. As a result, it is possible to prevent the formation of a portion where the rigidity is locally reduced on the outer side of the first outer end 13a in the tire axial direction, so that the deviation that tends to occur at the first outer end 13a of the third block 13 is likely to occur. It can exert traction and lateral grip while preventing wear and chipping.

It is desirable that the first end portion 19a of the groove-shaped element 19 is located on the second top portion 8 side between the first top portion 7 and the second top portion 8 of the second main groove 4B. By positioning the first end 19a on the second top 8 side in this way, the first outer end 13a of the third block 13 is located on the first tread end E1 side where the input in the tire axial direction during turning is large. It can be prevented from being distributed. As a result, the tire 1 can prevent uneven wear and chipping of the third block 13 together with the first block 11 and the second block 12 shown in FIG.

In order to further exert the above action, the first end portion 19a is the second of the second main groove 4B, similarly to the first end portion 18a of the groove-shaped element 18 of the second land portion 5B shown in FIG. It is desirable that it is located within a region (not shown) having a radius of 4 to 16 mm centered on the top portion 8.

At the first end 19a of the groove element 19, the angle (angle) θ4 formed by the groove center line 19c of the groove element 19 and the groove center line 4Bc of the second main groove 4B is appropriate. Can be set. It is desirable that the angle θ4 is set to 70 to 90 °, similarly to the angle θ3 of the second outer end 12b shown in FIG.

The second end portion 19b on the second tread end E2 side of the groove-shaped element 19 of the present embodiment communicates between the first top portion 7 and the second top portion 8 of the third main groove 4C. As a result, the circumferential edge 28 of the fourth block 14, which will be described later, is covered with the third block 13. Therefore, it is possible to prevent a portion where the rigidity is locally reduced from being formed on the outer side of the circumferential edge 28 in the tire axial direction, and it is possible to reduce slippage on the road surface at that portion. As a result, the tire 1 of the present embodiment can prevent uneven wear and chipping that are likely to occur at the circumferential edge 28 of the fourth block 14, and can improve uneven wear resistance and block chipping resistance.

At the second end 19b of the groove element 19, the angle (angle) θ5 formed by the groove center line 19c of the groove element 19 and the groove center line 4Cc of the third main groove 4C is appropriate. Can be set. It is desirable that the angle θ5 is set to 90 to 110 °, similarly to the angle θ2 of the first outer end 12a shown in FIG.

The groove-shaped element 19 of the present embodiment is configured as a sipe having a width W3 (shown in FIG. 1) of 1.5 mm or less. Since such a groove-shaped element 19 can prevent a portion of the third land portion 5C where the rigidity is locally reduced from being continuously formed in the tire axial direction, the uneven wear resistance and the resistance to uneven wear can be prevented. The block chipping performance can be improved. Further, the groove-shaped element 19 can increase the tire circumferential rigidity of the third land portion 5C, which is useful for exhibiting high traction. The width W3 may be set in the same range as the width W2 (shown in FIG. 1) of the groove-shaped element 18 of the second land portion 5B.

Each of the third blocks 13 is arranged so as to overlap each of the second blocks 12 in the tire circumferential direction. As a result, the tire 1 can suppress the formation of locally low-rigidity portions that are continuous in a straight line through the main groove 3, so that the tire 1 has improved traction and lateral grip, and has uneven wear resistance and resistance to uneven wear. The block chipping performance can be improved.

The third block 13 has a first portion 25 inclined in the first direction (downward to the right in the figure) with respect to the tire axial direction, and a second portion 25 in a direction opposite to the first direction with respect to the tire axial direction. It is configured to include a second portion 26 inclined in a direction (upward to the right in the figure). In the third block 13 of the present embodiment, the first portions 25 and 25 are connected to both ends of one second portion 26 in the tire circumferential direction, respectively. As a result, the third block 13 is configured as a zigzag (Z-shaped) block and has high torsional rigidity. The contour shape of the third block 13 of the present embodiment has a line-symmetrical shape in which the contour shape of the second block 12 is substantially inverted with respect to the tire circumferential direction line.

The second portion 26 of the present embodiment is configured to be longer in the tire circumferential direction than the first portions 25, 25, and can exhibit a large tire circumferential rigidity. Therefore, the third block 13 can improve the uneven wear resistance and the block chipping resistance.

The third block 13 includes at least one circumferential edge 27 extending in the tire circumferential direction on the second main groove 4B side. Such a circumferential edge 27 can provide an edge component in the tire circumferential direction, especially on a hard dirt road, and can enhance lateral grip. Further, since the circumferential edge 27 can increase the rigidity of the third block 13, it is possible to improve the uneven wear resistance and the block chipping resistance.

The circumferential edge 27 of the present embodiment is provided on the first top portion 7 of the second main groove 4B. Such a circumferential edge 27 can increase the rigidity of the third block 13 while providing an edge component in the tire circumferential direction on the first tread end E1 side where the contact pressure increases during turning. Therefore, the circumferential edge 27 can effectively improve the lateral grip and improve the uneven wear resistance and the block chipping resistance.

The tire circumferential length L3 of the circumferential edge (in this example, the circumferential edge provided on the first top portion 7) 27 of the third block 13 is the circumferential edge (book) of the second block 12 shown in FIG. In the example, it is desirable that the length L1 of the circumferential edge) 23 provided on the first top portion 7 is smaller than the length L1. As a result, the tire 1 can exhibit an edge component in the tire axial direction of the third block 13, which has a larger contact pressure during straight-ahead travel than the second block 12, and thus can exhibit traction during straight-ahead travel.

In order to further exert the above action, the length L3 of the circumferential edge (in this example, the circumferential edge provided on the first top portion 7) 27 of the third block 13 is the tire circumferential edge of the third block 13. It is desirable to set the length L4 (shown in FIG. 1) to 5% to 15%. By setting the length L3 of the circumferential edge 27 to 15% or less of the length L4 of the third block 13, traction during straight running can be effectively exhibited. On the other hand, by setting the length L3 of the circumferential edge 27 to 5% or more of the length L4 of the third block 13, the lateral grip can be effectively enhanced. From such a viewpoint, the length L3 of the circumferential edge 27 is preferably 12% or less, and preferably 8% or more of the length L4 of the third block 13.

FIG. 5 is a partially enlarged view illustrating an edge component of the third block 13. The third block 13 has an edge component Ec in the tire axial direction and an edge component Ed in the tire circumferential direction. The edge component Ec in the tire axial direction is projected onto the tire circumferential direction surface (plane parallel to the tire axial direction) with the length Ec1 when the third block 13 is projected on one side in the tire circumferential direction and on the other side. It shall be specified as the sum of the time length Ec2. On the other hand, the edge component Ed in the tire circumferential direction is the length when the third block 13 is projected onto one side in the tire axial direction on the tire circumferential direction surface (plane parallel to the tire equatorial line C (shown in FIG. 4)). It shall be specified as the sum of Ed1 and the length Ed2 when projected on the other side. The edge components of the first block 11 and the second block 12 shown in FIG. 2 can also be specified by the same procedure as the edge components of the third block 13.

The ratio Ea / Eb of the edge component Ea in the tire axial direction of the first block 11 (shown in FIG. 2) and the edge component Eb in the tire circumferential direction is the edge component Ec in the tire axial direction of the third block 13 and the tire circumferential direction. The ratio of Ec / Ed to the edge component Ed is preferably 85% to 95%.

By setting the ratio Ea / Eb to 95% or less of the ratio Ec / Ed, the tire circumference of the first block 11 with respect to the edge component in the tire axial direction has a larger contact pressure during turning than the third block 13. The ratio of the edge component in the direction can be relatively large. As a result, the tire 1 can improve the uneven wear resistance and the block chipping resistance while increasing the lateral grip of the first block 11.

By setting the ratio Ea / Eb to 85% or more of the ratio Ec / Ed, it is possible to prevent the ratio of the edge component in the tire circumferential direction of the first block 11 from becoming larger than necessary, so that traction during straight running can be suppressed. Can be maintained. From this point of view, the ratio Ea / Eb is preferably 92% or less of the ratio Ec / Ed, and preferably 88% or more.

The ratio Ee / Ef of the edge component Ee in the tire axial direction of the second block 12 (shown in FIG. 2) and the edge component Ef in the tire circumferential direction is the edge component Ec in the tire axial direction of the third block 13 and the tire circumferential direction. The ratio of Ec / Ed to the edge component Ed is preferably 80% to 90%.

By setting the ratio Ee / Ef to 90% or less of the ratio Ec / Ed, the tire with respect to the edge component in the tire axial direction for the second block 12, which has a larger contact pressure during turning than the third block 13. The ratio of the edge component in the circumferential direction can be made relatively large. As a result, the tire 1 can improve the uneven wear resistance and the block chipping resistance while increasing the lateral grip of the second block 12.

On the other hand, by setting the ratio Ee / Ef to 80% or more of the ratio Ec / Ed, it is possible to prevent the ratio of the edge component in the tire circumferential direction of the second block 12 from becoming larger than necessary, so that the vehicle travels straight. You can maintain the traction of time. From such a viewpoint, the ratio Ee / Ef is preferably 87% or less of the ratio Ec / Ed, and is preferably 83% or more.

[4th land area]
As shown in FIG. 1, the fourth land portion 5D is composed of a plurality of fourth blocks 14 separated by a groove-shaped element 20. The fourth land portion 5D of the present embodiment is provided with only the groove-shaped element 20 as a groove completely crossing the fourth land portion 5D.

The groove-shaped element 20 of the present embodiment is inclined in the first direction (downward to the right in the figure) with respect to the tire axial direction. Therefore, the groove-shaped element 20 is inclined in the same direction as the groove-shaped element 18 of the second land portion 5B and the tire axial direction, and is opposite to the groove-shaped element 19 of the third land portion 5C and the tire axial direction. Is inclined to.

As shown in FIG. 4, the first end portion 20a on the first tread end E1 side of the groove-shaped element 20 communicates with a position other than the second top portion 8 of the third main groove 4C. That is, the first end portion 20a of the present embodiment does not communicate with the circumferential edge 28 constituting the second top portion 8. As a result, with respect to the circumferential edge 27 of the third block 13 provided on the second top 8 of the third main groove 4C, the inside in the tire axial direction (second tread end E2 side) is covered by the fourth block 14. Will be. As a result, it is possible to prevent the formation of a portion where the rigidity is locally reduced on the inner side (second tread end E2 side) of the circumferential edge 27 in the tire axial direction, and thus slip on the road surface at that portion. Can be reduced. Therefore, the tire 1 of the present embodiment can exhibit traction and lateral grip while preventing uneven wear and chipping in the vicinity of the circumferential edge 27 of the third block 13.

In the present embodiment, of the outer ends 14a and 14b of the fourth block 14 in the tire circumferential direction, the first outer end 14a formed on the third main groove 4C side is the outer side in the tire axial direction (first tread end E1). The side) is covered by the third block 13. As a result, it is possible to prevent the formation of a portion where the rigidity is locally reduced on the outer side of the first outer end 14a in the tire axial direction, so that the deviation that tends to occur at the first outer end 14a of the fourth block 14 is likely to occur. It can exert traction and lateral grip while preventing wear and chipping.

Each of the fourth blocks 14 is arranged so as to overlap each of the third blocks 13 in the tire circumferential direction. As a result, the tire 1 can suppress the formation of locally low-rigidity portions that are continuous in a straight line through the main groove 3, so that the tire 1 has improved traction and lateral grip, and has uneven wear resistance and resistance to uneven wear. The block chipping performance can be improved.

The contour shape of the fourth block 14 of the present embodiment has a line symmetry shape in which the contour shape of the third block 13 is inverted with respect to the tire circumferential direction line. Therefore, like the third block 13, the fourth block 14 can effectively improve traction and lateral grip, while improving uneven wear resistance and block chipping resistance.

The groove-shaped element 20 of the present embodiment is configured as a sipe having a width W4 (shown in FIG. 1) of 1.5 mm or less. Since such a groove-shaped element 20 can prevent a portion of the fourth land portion 5D where the rigidity is locally reduced from being continuously formed in the tire axial direction, the uneven wear resistance and the resistance to uneven wear can be prevented. The block chipping performance can be improved. Further, the groove-shaped element 20 can increase the tire circumferential rigidity of the fourth land portion 5D, which is useful for exhibiting high traction. The width W4 may be set in the same range as the width W2 (shown in FIG. 1) of the groove-shaped element 18 of the second land portion 5B.

[Second tread pattern part]
As described above, the second tread pattern portion 3B shown in FIG. 1 has a line-symmetrical relationship with the first tread pattern portion 3A. Therefore, in the second tread pattern portion 3B, the main groove 4 corresponding to the main groove 4 of the first tread pattern portion 3A (in this example, the first main groove 4A to the fourth main groove 4D) (in this example, the first groove 4). 1 main groove 34A to 4th main groove 34D) are provided. The fourth main groove 34D of the second tread pattern portion 3B of the present embodiment is common to the fourth main groove 4D of the first tread pattern portion 3A.

The first main groove 34A to the fourth main groove 34D of the second tread pattern portion 3B and the first main groove 4A to the fourth main groove 4D of the first tread pattern portion 3A have zigzag phases aligned with each other. As a result, the tire 1 generates frictional force in the tire circumferential direction and the tire axial direction in a well-balanced manner in a wide range in the tire axial direction including the first tread pattern portion 3A and the second tread pattern portion 3B, and has excellent traction and laterality. You can exert a grip.

Further, in the second tread pattern portion 3B, the land portion 5 (first land portion 35A to fourth land portion) corresponding to the land portion 5 (first land portion 5A to fourth land portion 5D) of the first tread pattern portion 3A is provided. Section 35D) is provided. Therefore, the tire 1 of the present embodiment can exhibit traction and lateral grip while improving the uneven wear resistance and the block chipping resistance of the block formed on the second tread end E2 side.

[Land ratio]
The land ratio of the tread portion 2 is preferably 60 to 75%. As a result, the tire 1 can improve uneven wear resistance and block chipping resistance while exhibiting better traction and lateral grip on hard dirt roads. In the present specification, the land ratio is the actual tread area with respect to the total area of the treads calculated in the state where all the grooves are filled (that is, the slick state) between the first tread end E1 and the second tread end E2. Defined as a percentage of total area.

[Tire for running on rough terrain (second embodiment)]
In the embodiments so far, the case where the groove-shaped element (in this example, the groove-shaped element 18 to 20) is a sipe has been exemplified, but the present invention is not limited to such an embodiment. FIG. 6 is a development view showing an example of the tread portion 2 of the tire 1 for traveling on rough terrain according to another embodiment of the present invention. In FIG. 6, similarly to FIG. 1, in the first tread pattern portion 3A, four typical main grooves 4 are lightly colored. In this embodiment, the same configurations as those in the previous embodiments are designated by the same reference numerals, and the description thereof may be omitted.

The groove-shaped elements of this embodiment (groove-shaped elements 18 to 20 in this example) are configured as grooves having widths W2 to W4 larger than 1.5 mm. Such groove-shaped elements 18 to 20 form a water film or soil between the land portion 5 (in this example, the first land portion 5A to the fourth land portion 5D) and the road surface, and the main groove 4 (this example). Then, the guide can be smoothly guided to the first main groove 4A to the fourth main groove 4D) and the like. Further, the groove-shaped elements 18 to 20 can bite into the road surface and can exhibit excellent traction. In order to exert such an effect more, it is desirable that the widths W2 to W4 are set to 4 to 6 mm.

As shown in FIG. 2, the second block 12 of the embodiment so far is composed of one first portion 21 and a pair of second portions 22, 22 but is not limited to such an embodiment. .. As shown in FIG. 6, the second block 12 may be composed of a pair of first portions 21, 21 and three second portions 22, 22, 22. In the present embodiment, one second portion 22 is arranged between the first portions 21 and 21, and the second portions 22 and 22 are arranged at both ends of the first portions 21 and 21 in the tire circumferential direction, respectively. There is.

The second block 12 of this embodiment can exhibit a large tire circumferential rigidity as compared with the second block 12 of the previous embodiments shown in FIG. 2. Further, the second block 12 of this embodiment can reduce the number of outer ends 12a and 12b shown in FIG. 2 as compared with the second block 12 of the previous embodiments. Therefore, even if the groove-shaped element 18 is formed as a groove as in this embodiment, the uneven wear resistance and the block chipping resistance can be improved.

The second block 12 of this embodiment includes two circumferential edges 23, 23 extending in the tire circumferential direction on the first main groove 4A side. Such two circumferential edges 23, 23 can provide an edge component in the tire circumferential direction, especially on hard dirt roads, and can enhance lateral grip. Further, since the circumferential edges 23 and 23 can increase the rigidity of the second block 12, the uneven wear resistance and the block chipping resistance can be improved.

In order to further exert the above action, the total value of the tire circumferential lengths L1 of the circumferential edges (in this example, the circumferential edges provided on the first top portion 7) 23 and 23 of the second block 12 is set. It is desirable that the length L2 of the second block 12 in the tire circumferential direction is set to 15% to 25%.

Although the particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments.

[Example A]
Hereinafter, more specific and non-limiting examples of the present invention will be described. Tires for running on rough terrain having the basic pattern shown in FIG. 1 were prototyped (Examples 1 to 5). For comparison, the tire for running on rough terrain having the pattern of Patent Document 1 (pattern in FIG. 7: Comparative Example 1) and the first end portion of the groove-shaped element on the first tread end side are the first main groove. A tire for running on rough terrain (pattern in FIG. 8: Comparative Example 2) having a pattern communicating with the second top was prototyped. The internal structure and rubber composition of these tires are set to be the same.

Then, these tires were evaluated for traction performance, lateral grip, uneven wear resistance, and block chipping resistance. Furthermore, the running time when the vehicle equipped with each tire was run on the test course was measured. The common specifications are as follows.
Tire size: 205 / 65R15
Rim size: 15 x 7.0J
Internal pressure (front and rear wheels): 200kPa
Vehicle: Four-wheel drive vehicle with a displacement of 2000cc Main groove:
Groove width W1: 6.5mm
Angle θ1: 45 °
Second block:
Peripheral edge length L1 / 2nd block length L2: 20%
Angle of the first end θ2: 100 °
Angle of the second end θ3: 80 °
Third block:
Circumferential edge length L3 / 3rd block length L4: 10%
Angle of the first end θ4: 80 °
Angle of the second end θ5: 100 °
Edge component ratio:
(Ratio of 1st block Ea / Eb) / (Ratio of 3rd block Ec / Ed): 90%
(Ratio of 2nd block Ee / Ef) / (Ratio of 3rd block Ec / Ed): 85%
Groove element: Sipe (width 1.0 mm)
Land ratio: 68%
The test method is as follows.

<Traction performance and lateral grip>
The vehicle equipped with each tire was run on a hard dirt road. Then, due to the sensuality of the test driver, the traction performance and lateral grip of each tire were evaluated by an index with Comparative Example 1 as 100. The higher the number, the better.

<Running time>
The time when the vehicle equipped with each tire was run once on a test course consisting of a hard dirt road was measured. The result is displayed as an index with Comparative Example 1 as 100 for the reciprocal of the time of each tire. The larger the value, the shorter the running time and the better.

<Uneven wear resistance>
After the vehicle equipped with each tire was run for 1000 km on a hard dirt road, the presence or absence of locally worn blocks was visually observed for the blocks provided on the tread end side. The results are shown as an exponent with Comparative Example 1 as 100 for the reciprocal of the number of locally worn blocks. The larger the value, the better the uneven wear resistance.

<Block chipping resistance>
After the vehicle equipped with each tire was run for 1000 km on a hard dirt road, the presence or absence of locally chipped blocks was visually observed for the blocks provided on the tread end side. The result is shown by an exponent with Comparative Example 1 as 100 for the reciprocal of the number of blocks in which the chip has occurred. The larger the value, the better the block chipping resistance.
The test results are shown in Table 1.

As a result of the test, it was confirmed that the tire of the example improved the uneven wear resistance performance and the block chipping resistance of the block formed on the tread end side as compared with the tires of Comparative Example 1 and Comparative Example 2. Further, it was confirmed that the tires of the examples could improve the traction performance and the lateral grip as compared with the tires of Comparative Example 1 and Comparative Example 2, and the running time was good.

Further, in Examples 2 to 4, since the distance (radius) R1 between the first end portion and the second top portion is in a preferable range, it is formed on the tread end side as compared with Examples 1 and 5 which are not in the preferable range. It was possible to effectively improve the uneven wear resistance and chipping resistance of the block.

[Example B]
A tire for running on rough terrain having the basic pattern shown in FIG. 1 was prototyped (Examples 3 and 6 to 13). The internal structure and rubber composition of these tires are set to be the same. Then, for each tire, the traction performance, the lateral grip, the uneven wear resistance and the block chipping resistance were evaluated, and the running time was measured. The common specifications are the same as those of Example A except for the specifications shown in Table 2 and the following specifications. The test method is the same as that of Example A.
Pattern diagram: Fig. 1
Distance (radius) between the first end and the second top R1: 10 mm
The test results are shown in Table 2.

As a result of the test, Example 3, Example 7-8 and Example 11-12, in which the ratio L1 / L2 and the ratio L3 / L4 are preferable, have the uneven wear resistance performance and the block chipping resistance performance as compared with the other examples. While maintaining it, we were able to improve traction performance and lateral grip.

[Example C]
A tire for running on rough terrain having the basic pattern shown in FIG. 1 was prototyped (Example 3 and Examples 14 to 21). The internal structure and rubber composition of these tires are set to be the same. Then, for each tire, the traction performance, the lateral grip, the uneven wear resistance and the block chipping resistance were evaluated, and the running time was measured. The common specifications are the same as those of Example A except for the specifications shown in Table 3 and the following specifications. The test method is the same as that of Example A.
Pattern diagram: Fig. 1
Distance (radius) between the first end and the second top R1: 10 mm
The test results are shown in Table 3.

As a result of the test, Examples 3, 15-16 and 19-20, in which the angles θ2 to θ5 are preferable, have traction resistance while maintaining uneven wear resistance and block chipping resistance as compared with the other examples. The performance and lateral grip could be improved.

[Example D]
Tires for running on rough terrain having the basic pattern shown in FIG. 1 were prototyped (Examples 3 and 22 to 29). The internal structure and rubber composition of these tires are set to be the same. Then, for each tire, the traction performance, the lateral grip, the uneven wear resistance and the block chipping resistance were evaluated, and the running time was measured. The common specifications are the same as those of Example A except for the specifications shown in Table 4 and the following specifications. The test method is the same as that of Example A.
Pattern diagram: Fig. 1
Distance (radius) between the first end and the second top R1: 10 mm
The test results are shown in Table 4.

As a result of the test, Examples 3, 23-24 and 27-28, which have a preferable ratio of edge components, have traction resistance while maintaining uneven wear resistance and block chipping resistance as compared with other examples. The performance and lateral grip could be improved.

A tire for running on rough terrain having the basic pattern shown in FIG. 1 was prototyped (Example 3). Further, a tire for running on rough terrain having the basic pattern shown in FIG. 6 was prototyped (Example 30). Further, a tire for running on rough terrain, in which the second block shown in FIG. 6 is composed of three first parts and five second parts, was prototyped (Example 31). The internal structure and rubber composition of these tires are set to be the same. Then, for each tire, the traction performance, the lateral grip, the uneven wear resistance and the block chipping resistance were evaluated, and the running time was measured. The common specifications are the same as those of Example A except for the specifications shown in Table 5 and the following specifications. The test method is the same as that of Example A.
Distance (radius) between the first end and the second top R1: 10 mm
The test results are shown in Table 5.

As a result of the test, the tire of the example was able to improve the traction performance and the lateral grip while maintaining the uneven wear resistance and the block chipping resistance.

4 Main groove 4A 1st main groove 4B 2nd main groove 5 Land part 5A 1st land part 5B 2nd land part 11 1st block 12 2nd block 18 Groove-shaped element

Claims (14)

A tire for running on rough terrain having a tread portion defined by a first tread end and a second tread end.
The tread portion includes a plurality of main grooves continuously extending in a zigzag shape in the tire circumferential direction, and a plurality of land portions divided by the main grooves.
The main groove includes a first main groove arranged closest to the first tread end and a second main groove adjacent to the first main groove.
The first main groove and the second main groove have zigzag phases aligned with each other.
The first main groove and the second main groove include a first top portion that is convex toward the end side of the first tread and a second top portion that is convex toward the end side of the second tread.
The land portion includes a first land portion between the first tread end and the first main groove, and a second land portion between the first main groove and the second main groove.
The first land portion is composed of a plurality of first blocks, and each of the first blocks is provided with a tapered portion whose length in the tire circumferential direction decreases toward the end side of the second tread.
The second land portion is composed of a plurality of second blocks separated by a groove-shaped element, and the first end portion of the groove-shaped element on the first tread end side is other than the second top portion of the first main groove. Communicate with the position of
Tires for running on rough terrain. The tire for running on rough terrain according to claim 1, wherein the first end portion is located on the second top side between the first top portion and the second top portion of the first main groove. .. The tire for running on rough terrain according to claim 1 or 2, wherein the first end portion is located in a region having a radius of 4 to 16 mm centered on the second top portion. According to any one of claims 1 to 3, the angle between the groove center line of the groove-shaped element and the groove center line of the first main groove at the first end portion is 90 to 110 °. Tires for running on rough terrain as described. The second end portion of the groove-shaped element on the second tread end side communicates between the first top portion and the second top portion of the second main groove.
According to any one of claims 1 to 4, the angle between the groove center line of the groove-shaped element and the groove center line of the second main groove at the second end is 70 to 90 °. Tires for running on rough terrain as described. The second block includes at least one circumferential edge extending in the tire circumferential direction on the first main groove side.
The rough terrain running according to any one of claims 1 to 5, wherein the tire circumferential length of the circumferential edge is 15% to 25% of the tire circumferential length of the second block. Tires. The second block has a first portion inclined in the first direction with respect to the tire axial direction and a second portion inclined in a second direction opposite to the first direction with respect to the tire axial direction. The tire for running on rough terrain according to any one of claims 1 to 6, including the above. The main groove further includes a third main groove adjacent to the second main groove.
The third main groove has a zigzag phase aligned with the first main groove and the second main groove.
The land portion further includes a third land portion between the second main groove and the third main groove.
The third land portion is composed of a plurality of third blocks separated by a groove-shaped element, and the first end portion of the groove-shaped element on the first tread end side is the second top portion of the second main groove. The tire for running on rough terrain according to any one of claims 1 to 7, which communicates with a position other than the above. The third block includes at least one circumferential edge extending in the tire circumferential direction on the second main groove side.
The tire for running on rough terrain according to claim 8, wherein the tire circumferential length of the circumferential edge is 5% to 15% of the tire circumferential length of the third block. The ratio Ea / Eb of the edge component Ea in the tire axial direction of the first block and the edge component Eb in the tire circumferential direction is the ratio Ea / Eb of the edge component Ec in the tire axial direction and the edge component Ed in the tire circumferential direction of the third block. The tire for running on rough terrain according to claim 8 or 9, which has a ratio of Ec / Ed of 85% to 95%. The ratio Ee / Ef of the edge component Ee in the tire axial direction of the second block and the edge component Ef in the tire circumferential direction is the ratio Ee / Ef of the edge component Ec in the tire axial direction and the edge component Ed in the tire circumferential direction of the third block. The tire for running on rough terrain according to any one of claims 8 to 10, which is 80% to 90% of the ratio Ec / Ed. The tire for traveling on rough terrain according to any one of claims 1 to 11, wherein the groove-shaped element is a sipe having a width of 1.5 mm or less. The tire for running on rough terrain according to any one of claims 1 to 12, wherein the groove-shaped element is a groove having a width larger than 1.5 mm. The tire for traveling on rough terrain according to any one of claims 1 to 13, wherein the land ratio of the tread portion is 60% to 75%.

Images