Tire for rough terrain travel

Abstract

To provide an off-road traveling tire that provides improved traction performance and steering stability on the off-road.SOLUTION: An off-road traveling tire includes a tread portion 2. Crown blocks 5, middle blocks 6, and groove portions 7 are formed on the tread portion 2. The crown blocks 5 each include a tread surface 10 and a first wall surface 11 located on the heel-side in a tire rotation angle R. The first wall surface 11 is inclined to the toe-side in the tire rotation angle R from the tread surface 10 toward the inner side in the tire radial direction. A length La in the tire axial direction of the groove portion 7 is 5% to 70% of a length Lm in the tire axial direction of the middle block 6.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a tire for rough terrain driving.

Background Art

[0002] Patent Document 1 below describes a pneumatic tire having a plurality of blocks provided in a tread portion. Each of the front-contact-side block wall surface and the rear-contact-side block wall surface of the block is formed of an inclined block inclined in a direction in which both the front-contact edge and the rear-contact edge advance to the front-contact side from the base of each block wall surface. Such inclined blocks are said to have a high road surface digging ability and exhibit excellent running performance on rough terrain.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in recent years, there has been a demand for further improving the traction performance and handling stability performance on rough terrain.

[0005] The present invention has been devised in view of the above actual situation, and the main object thereof is to provide a tire for rough terrain driving with improved traction performance and handling stability performance on rough terrain.

Means for Solving the Problems

[0006] The present invention relates to a tire for rough terrain travel having a tread portion, wherein the tread portion has a specified tire rotation direction, and the tread portion is provided with crown blocks, middle blocks located outside the crown blocks in the tire axial direction, and groove portions located between the crown blocks and the middle blocks. The crown blocks include a tread surface, a first wall surface located on the leading side in the tire rotation direction, and a first edge at the intersection of the tread surface and the first wall surface. The first wall surface is inclined from the tread surface toward the inside in the tire radial direction and toward the trailing side in the tire rotation direction. The length of the groove portion in the tire axial direction is 5% to 70% of the length of the middle block in the tire axial direction.

[0007] It is desirable that the tire for rough terrain travel according to the present invention has the crown block including a second wall surface located on the trailing side in the tire rotation direction and a second edge at the intersection of the tread surface and the second wall surface, and the second wall surface is inclined from the tread surface toward the inside in the tire radial direction and toward the trailing side in the tire rotation direction.

[0008] It is desirable that the tire for rough terrain travel according to the present invention has the first wall surface and the second wall surface each including an outer portion of the first wall surface and an outer portion of the second wall surface from the first edge and the second edge to 50% of the block height of the crown block, and an angle α of the outer portion of the first wall surface with respect to the normal line of the tread surface passing through the first edge is smaller than an angle β of the outer portion of the second wall surface with respect to the normal line of the tread surface passing through the second edge.

[0009] It is desirable that the angle α of the tire for rough terrain travel according to the present invention is 45 degrees or less.

[0010] It is desirable that the angle β of the tire for rough terrain travel according to the present invention is 5 to 70 degrees.

[0011] The tire for rough terrain travel according to the present invention preferably includes a first portion where the outer side of the second wall surface extends inward in the tire radial direction from the second edge, and a second portion that is located more inward in the tire radial direction than the first portion and is inclined more gently than the first portion.

[0012] The tread surface of the crown block of the tire for rough terrain travel according to the present invention has a first point located at the most leading side in the tire rotation direction, a second point located at the most leading side in the tire rotation direction on the tire equator, and a third point located at the most trailing side in the tire rotation direction on the tire equator. In a plan view of the tread portion, it is desirable that at least a part of the middle block is located between a first virtual straight line passing through the first point and the second point and a second virtual straight line obtained by translating the first virtual straight line parallel to the third point.

[0013] It is desirable that the angle of the first virtual straight line with respect to the tire circumferential direction is 45 to 89 degrees for the tire for rough terrain travel according to the present invention.

[0014] It is desirable that the crown block of the tire for rough terrain travel according to the present invention straddles the tire equator.

[0015] It is desirable that the crown block of the tire for rough terrain travel according to the present invention extends toward the leading side in the tire rotation direction from both sides in the tire axial direction from the tire equator.

Advantages of the Invention

[0016] By adopting the above configuration, the tire for rough terrain travel of the present invention can improve the traction performance and handling stability performance on rough terrain.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a tire meridian cross-sectional view including a tire rotation axis (not shown) in a normal state of an off-road running tire (hereinafter sometimes simply referred to as "tire") 1 according to an embodiment of the present invention. FIG. 2 is a developed view of the tread portion 2 of the tire 1. As shown in FIGS. 1 and 2, the tire 1 of the present embodiment is a tire for a motorcycle.

[0019] The "normal state" is a no-load state in which the tire 1 is rim-mounted on a normal rim (not shown) and filled with a normal internal pressure. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in this normal state.

[0020] The "normal rim" is a rim defined for each tire in a standard system including the standard on which the tire 1 is based. For example, in the case of JATMA, it is the "standard rim", in the case of TRA, it is the "Design Rim", and in the case of ETRTO, it is the "Measuring Rim".

[0021] The "normal internal pressure" is the air pressure defined for each tire in a standard system including the standard on which the tire 1 is based. In the case of JATMA, it is the "maximum air pressure", in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is the "INFLATION PRESSURE".

[0022] In the cross-section, the outer surface of the tread portion 2 of the tire 1 of the present embodiment is curved in an arc shape convex in the outer side in the tire radial direction. Further, the tread portion 2 of the tire 1 has a directional pattern in which the tire rotation direction R is specified.

[0023] In the tread portion 2 of the present embodiment, a crown block 5, a middle block 6 located outside the crown block 5 in the tire axial direction, and a groove portion (which may be referred to as a "middle groove portion" in this specification) 7 located between the crown block 5 and the middle block 6 are provided.

[0024] FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2. The line A-A extends along the tire circumferential direction. As shown in FIGS. 2 and 3, the crown block 5 of the present embodiment includes a tread surface 10, a first wall surface 11 located on the leading side in the tire rotation direction R, and a first edge 12 at the intersection of the tread surface 10 and the first wall surface 11. The tread surface 10 is an area that contacts the ground in a plane when the tire 1 in the normal state is running under a normal load.

[0025] The "normal load" is the load determined for each tire in a standard system including the standards on which the tire 1 is based. For JATMA, it is the "maximum load capacity"; for TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; for ETRTO, it is the "LOAD CAPACITY".

[0026] The first wall surface 11 is inclined toward the trailing side in the tire rotation direction R from the tread surface 10 inward in the tire radius direction. The crown block 5 having such a first wall surface 11 digs up the uneven road surface covered with mud and generates high traction.

[0027] The tire axial length La of the groove portion 7 is 5% to 70% of the tire axial length Lm of the middle block 6. Since the length La of the groove portion 7 is 70% or less of the length Lm of the middle block 6, the discharge (escape) of the dug-up mud from the groove portion 7 is restricted within a certain range, and it can be compacted and sheared, so that a greater traction is generated. Since the length La of the groove portion 7 is 5% or more of the length Lm of the middle block 6, continuous clogging of the groove portion 7 after grounding is suppressed. Thereby, at the time of turning or the like, the edges 5e, 6e on the groove portion 7 side of the crown block 5 and the middle block 6 can be effectively utilized, and excellent handling stability is exhibited.

[0028] In order to effectively exhibit the above-described action, it is desirable that the length La of the groove portion 7 is 20% or more of the length Lm of the middle block 6, more desirably 30% or more, desirably 60% or less, and more desirably 50% or less.

[0029] In the tread portion 2 of the present embodiment, a shoulder block 8 located outside the middle block 6 in the tire axial direction and a groove portion 9 located between the shoulder block 8 and the middle block 6 are provided. The shoulder block 8 includes, for example, an outer edge 8e located at the outermost position in the tire axial direction. The outer edge 8e forms a tread end Te extending in the tire circumferential direction.

[0030] In the present embodiment, the tread portion 2 is formed in a line-symmetric pattern with the tire equator C as the center line. The crown block 5 straddles, for example, the tire equator C. The middle block 6 and the shoulder block 8 are provided, for example, on both sides in the tire axial direction of the crown block 5. Further, in the present embodiment, the blocks 5, 6, 8 are arranged at the same pitch in the tire circumferential direction.

[0031] As shown in FIG. 3, the crown block 5 includes, for example, a second wall surface 13 located on the trailing side in the tire rotation direction R and a second edge 14 at the intersection of the tread surface 10 and the second wall surface 13.

[0032] In this embodiment, the second wall surface 13 is inclined toward the trailing side in the tire rotation direction R from the tread surface 10 toward the inner side in the tire radial direction. Such a second wall surface 13 increases the rigidity of the crown block 5 and suppresses the twisting of the crown block 5 during running. As a result, the effect of digging up mud is improved.

[0033] The first wall surface 11 and the second wall surface 13 each include a first wall surface outer portion 16 and a second wall surface outer portion 19 from the first edge 12 and the second edge 14 to 50% of the block height H1 of the crown block 5. The angle α of the first wall surface outer portion 16 with respect to the normal line 10a of the tread surface 10 passing through the first edge 12 is formed smaller than the angle β of the second wall surface outer portion 19 with respect to the normal line 10b of the tread surface 10 passing through the second edge 14. Since the angle α is smaller than the angle β, the twisting of the crown block 5 during running is greatly suppressed, and mud can be dug up more effectively. The angle β is specified as the angle between the virtual straight line 19x passing through the inner end 19i in the tire radial direction of the second wall surface outer portion 19 and the second edge 14 and the normal line 10b when the second wall surface outer portion 19 extends in an arc shape or a stepped shape, in other words, when it does not extend linearly. The angle α is specified in the same manner as the angle β.

[0034] In order to effectively exhibit the above-described action, the angle α may exceed 0 degrees, but is preferably 5 degrees or more, and more preferably 15 degrees or more. Also, if the angle α is excessively large, the rigidity of the inner portion of the crown block 5 in the tire radial direction decreases, and the risk of block chipping, cracking, etc. increases. For this reason, the angle α is preferably 45 degrees or less, and more preferably 35 degrees or less.

[0035] In order to increase the rigidity of the crown block 5, the angle β is preferably 5 degrees or more, and more preferably 20 degrees or more. If the angle β is excessively large, the distance between the crown blocks 5 arranged in the tire circumferential direction increases, the frequency of digging up mud decreases, and the traction performance may deteriorate. For this reason, the angle β is preferably 70 degrees or less, and more preferably 60 degrees or less.

[0036] In order to effectively exert the above-described effects, the difference (β - α) between the angle β and the angle α is desirably 5 degrees or more, more desirably 10 degrees or more, desirably 50 degrees or less, and more desirably 40 degrees or less.

[0037] The outer portion 16 of the first wall surface extends linearly from the first edge 12, for example. Note that the outer portion 16 of the first wall surface is not limited to such a form, and may be formed, for example, in an arcuate shape that is concave on the trailing side in the tire rotation direction R with respect to the crown block 5.

[0038] In the present embodiment, the outer portion 19 of the second wall surface includes a first portion 21 that extends from the second edge 14 toward the inside in the tire radial direction, and a second portion 22 that is located on the inside in the tire radial direction with respect to the first portion 21 and is inclined more gently than the first portion 21. The first portion 21 serves to increase the rigidity of the portion on the tread surface 10 side of the crown block 5 where a particularly large force acts, and helps to improve the traction performance. In the present embodiment, the first portion 21 extends linearly. The first portion 21 and the second portion 22 are inclined toward the trailing side in the tire rotation direction R toward the inside in the tire radial direction, for example. In the present embodiment, the first portion 21 and the second portion 22 are connected via an arcuate portion 23 that is convex on the leading side in the tire rotation direction R.

[0039] The first wall surface 11 includes an inner portion 17 of the first wall surface that is continuous with the outer portion 16 of the first wall surface and is located on the inside in the tire radial direction of the outer portion 16 of the first wall surface. The second wall surface 13 includes an inner portion 20 of the second wall surface that is continuous with the outer portion 19 of the second wall surface and is located on the inside in the tire radial direction of the outer portion 19 of the second wall surface. The inner portion 17 of the first wall surface is formed, for example, in an arcuate shape that is concave on the trailing side in the tire rotation direction R of the crown block 5. The inner portion 20 of the second wall surface is formed, for example, in an arcuate shape that is convex on the leading side in the tire rotation direction R of the crown block 5. In the present embodiment, the inner portion 20 of the second wall surface is formed by an arc having a larger radius of curvature than the inner portion 17 of the first wall surface. The inner portion 17 of the first wall surface and the inner portion 20 of the second wall surface are not limited to such forms.

[0040] Figure 4 is an enlarged view of the crown block 5 and the middle block 6. As shown in Figure 4, in this embodiment, the crown block 5 extends in the leading side in the tire rotation direction R from both sides in the tire axial direction from the tire equator C. Such a crown block 5 helps to gather the dug-up mud toward the center side in the tire axial direction of the crown block 5 and compact it.

[0041] The tread surface 10 of the crown block 5 has a first point 25 located on the leading side most in the tire rotation direction R, a second point 26 located on the leading side most on the tire equator C in the tire rotation direction R, and a third point 27 located on the trailing side most on the tire equator C in the tire rotation direction R. And in the plan view of the tread portion 2, at least a part of the middle block 6 is located between a first virtual straight line M1 passing through the first point 25 and the second point 26 and a second virtual straight line M2 obtained by translating the first virtual straight line M1 parallelly onto the third point 27. Thereby, the middle block 6 suppresses the dug-up mud by the crown block 5 from being discharged from the groove portion 7 or the like, and further enhances the traction performance. In order to effectively exert such an action, it is desirable that 70% or more of the area Am of the tread surface 6a of the middle block 6 is located between the first virtual straight line M1 and the second virtual straight line M2, and it is more desirable that 80% or more of the area Am is located.

[0042] The angle θ1 of the first virtual straight line M1 with respect to the tire circumferential direction is preferably 45 to 89 degrees. Since the angle θ1 is 45 degrees or more, a large shearing force is exerted on the mud. Since the angle θ1 is 89 degrees or less, the mud dug up by the crown block 5 is suppressed from escaping to the outside in the tire axial direction of the crown block 5. From such a viewpoint, the angle θ1 is more preferably 60 degrees or more, still more preferably 65 degrees or more, further preferably 80 degrees or less, and still more preferably 75 degrees or less.

[0043] In this embodiment, the crown block 5 includes a crown projection 30 that extends in the tire circumferential direction across the second edge 14. The crown block 5 includes, for example, the crown projection 30 and a crown main portion 31 formed so as to straddle the tire equator C. The crown projection 30 is provided on both sides of the tire equator C. Such a crown projection 30 further suppresses, for example, the crown block 5 from twisting toward the trailing side in the tire rotation direction R when the tire is in contact with the ground.

[0044] In a plan view of the tread, the crown projection 30 has a rectangular shape in which the length Lb in the tire circumferential direction is larger than the length Le in the tire axial direction. Such a crown projection 30 effectively enhances the above-described action. In this embodiment, the crown projection 30 is formed in a parallelogram shape. The crown projection 30 may be, for example, rectangular. For example, the outer surface 30a of the crown projection 30 in the tire radial direction is located between the tire equator C and the first point 25 of the crown block 5.

[0045] It is desirable that the length Lb in the tire circumferential direction of such a crown projection 30 be 1.0 times or more, more desirably 1.3 times or more, 3.0 times or less, and more desirably 2.5 times or less the length Ld in the tire circumferential direction of the edge 5e of the crown block 5. Also, it is desirable that the length Le in the tire axial direction of the crown projection 30 be 5% or more, more desirably 7% or more, 13% or less, and more desirably 11% or less the length Lc (shown in FIG. 2) in the tire axial direction of the crown block 5. Further, it is desirable that the length Lb in the tire circumferential direction of the crown projection 30 be 2.5 times or more, more desirably 3.0 times or more, 4.5 times or less, and more desirably 4.0 times or less the length Le in the tire axial direction.

[0046] In the present embodiment, the outer surface 30a of the crown projection 30 in the tire radial direction includes a lateral edge 33a that is arranged on the leading side in the tire rotation direction R and extends in the tire axial direction, and a pair of longitudinal edges 33b, 33b that extend in the tire circumferential direction on both sides in the tire axial direction. The outer surface 30a of the crown projection 30 in the tire radial direction is preferably arranged on the outer side or at the same position in the tire radial direction compared to the outer surface 31a (the same as the tread surface 10) of the crown main portion 31. Such a crown projection 30 exerts the effect of enhancing the traction performance by the lateral edge 33a and the pair of longitudinal edges 33b during straight and turning running. The crown projection 30 and the crown main portion 31 are, for example, separated by a recess 32 that is recessed inward in the tire radial direction compared to the outer surface 31a of the crown main portion 31. In the present embodiment, the recess 32 is formed in a shape that sandwiches the crown projection 30, such as substantially U-shaped or substantially C-shaped in a tread plan view.

[0047] In the present embodiment, the crown main portion 31 is formed in a V shape that extends from the tire equator C toward both sides in the tire axial direction on the leading side in the tire rotation direction R.

[0048] The tire axial length Lc of the crown block 5 is preferably 20% or more of the tread development width TW, more preferably 25% or more, preferably 40% or less, and more preferably 35% or less. Also, the tire circumferential length Ld of the edge 5e of the crown block 5 is preferably 15% or more of the tire axial length Lc of the crown block 5, more preferably 20% or more, preferably 35% or less, and more preferably 30% or less. The tread development width TW is the tire axial distance between the tread ends Te, Te when the tread portion 2 is developed in a plane.

[0049] The middle block 6 includes, for example, a middle main portion 35 that is inclined toward the leading side in the tire rotation direction R toward the outer side in the tire axial direction, and a middle projection 36 that extends from the middle main portion 35 to the trailing side in the tire rotation direction R.

[0050] The middle main part 35 is formed in an L shape, including, for example, an equal-length part 35A having the same length in the tire circumferential direction and an extended part 35B connected to the equal-length part 35A and having an increasing length in the tire circumferential direction toward the outer side in the tire axial direction. The "same length" means a mode in which the difference (S - s) between the maximum value S and the minimum value s of the length in the tire circumferential direction of the equal-length part 35A is within 10% of the maximum value S. In this embodiment, the equal-length part 35A is located on the leading side in the tire rotation direction R with respect to the second virtual straight line M2. In this embodiment, the extended part 35B straddles the second virtual straight line M2 and is located on both sides in the tire circumferential direction.

[0051] The outer surface 36a of the middle protrusion 36 in the tire radial direction is arranged, for example, on the outer side or at the same position in the tire radial direction compared to the outer surface 35a (the same as the tread surface 6a) of the middle main part 35 in the tire radial direction. Such a middle protrusion 36 exerts an effect of enhancing the traction performance during straight and turning running.

[0052] Although not particularly limited, the length Lm of the middle block 6 in the tire axial direction is preferably 5% or more of the tread development width TW, more preferably 10% or more, preferably 20% or less, and more preferably 15% or less.

[0053] The tread rubber 2G (shown in FIG. 1) in which such blocks 5, 6, and 8 are formed preferably has a complex elastic modulus E* of 10 to 40 MPa. In this specification, the complex elastic modulus E* is a value measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under the following conditions in accordance with the provisions of JIS-K6394. Initial strain: 1% Amplitude: ±2% Frequency: 10 Hz Deformation mode: Tension Temperature: 30 °C

[0054] As described above, the particularly preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the illustrated embodiments and can be implemented in various forms. All the front-wheel tires have the same tread pattern.

Example

[0055] A rear wheel tire for a two - wheeled vehicle for rough terrain having the basic pattern of FIG. 2 was prototyped based on the specifications in Table 1. Then, tests were conducted on the traction performance and handling stability performance of each test tire. The common specifications and test methods of each test tire are as follows. Vehicle in use: A motocross competition vehicle with a displacement of 450 cc Tire size (front wheel, rear wheel): 80 / 100 - 21, 120 / 80 - 19 Rim size (front wheel, rear wheel): 21×1.60, 19×2.15 Inner pressure: 80 kPa The test method is as follows.

[0056] <Traction performance and handling stability performance> The traction performance and handling stability performance when the test vehicle was driven on rough terrain covered with mud were evaluated by the senses of the test rider. Here, the "traction performance" is the evaluation of the smoothness of driving when accelerating during straight - line driving and turning driving by the senses of the test rider. The "handling stability performance" is the evaluation of the stability of driving including handle operation during straight - line driving and turning driving by the senses of the test rider. Each test is shown on a 10 - point scale with 10 points as the full score. The test results are shown in Table 1.

[0057]

Table 1

[0058] As a result of the test, it is understood that the tires of the example have improved traction performance and handling stability performance on rough terrain compared to the tires of the comparative example.

[0059] 1 Tire for rough - terrain driving 2 Tread part 5 Crown block 6 Middle block 7 Groove part 10 Tread surface 11 First wall surface La Length of groove part 7 Lm Length of middle block

Claims

1. A tire for rough terrain travel having a tread portion, wherein the tread portion has a specified tire rotation direction, the tread portion is provided with a crown block, a middle block located outside the crown block in the tire axial direction, and a groove portion located between the crown block and the middle block, the crown block includes a tread surface, a first wall surface located on the leading side in the tire rotation direction, and a first edge at the intersection of the tread surface and the first wall surface, the first wall surface is inclined from the tread surface inward in the tire radius direction toward the trailing side in the tire rotation direction, the length of the groove portion in the tire axial direction is 5% to 70% of the length of the middle block in the tire axial direction, the tread surface of the crown block has a first point located at the most leading side in the tire rotation direction, a second point located at the most leading side on the tire equator in the tire rotation direction, and a third point located at the most trailing side on the tire equator in the tire rotation direction, in a plan view of the tread portion, at least a part of the middle block is located between a first virtual straight line passing through the first point and the second point and a second virtual straight line obtained by parallel - translating the first virtual straight line onto the third point, the angle of the first virtual straight line with respect to the tire circumferential direction is 45 to 89 degrees, the middle block has more than 70% of the area of the tread surface of the middle block located between the first virtual straight line and the second virtual straight line, a tire for rough terrain travel.

2. The crown block includes a second wall surface located on the trailing side in the tire rotation direction, and a second edge at the intersection of the tread surface and the second wall surface, the second wall surface is inclined from the tread surface inward in the tire radius direction toward the trailing side in the tire rotation direction. The tire for rough terrain travel according to Claim 1.

3. The first wall surface and the second wall surface each include a first outer wall surface portion and a second outer wall surface portion from the first edge and the second edge to 50% of the block height of the crown block, the angle α of the first outer wall surface portion with respect to the normal line of the tread surface passing through the first edge is smaller than the angle β of the second outer wall surface portion with respect to the normal line of the tread surface passing through the second edge. The tire for rough terrain travel according to Claim 2.

4. The angle α is 45 degrees or less. The tire for rough terrain travel according to Claim 3.

5. The angle β is 5 to 70 degrees, and the tire for rough terrain travel according to claim 3 or 4.

6. The outer portion of the second wall surface includes a first portion extending inward in the tire radial direction from the second edge, and a second portion located more inward in the tire radial direction than the first portion and inclined more gently than the first portion. The tire for rough terrain travel according to any one of claims 3 to 5.

7. The angle of the first virtual straight line with respect to the tire circumferential direction is 45 to 80 degrees, and the tire for rough terrain travel according to any one of claims 1 to 6.

8. The angle of the first virtual straight line with respect to the tire circumferential direction is 45 to 75 degrees, and the tire for rough terrain travel according to any one of claims 1 to 7.

9. The crown block straddles the tire equator, and the tire for rough terrain travel according to any one of claims 1 to 8.

10. The crown block extends toward the leading side in the tire rotation direction from both sides in the tire axial direction from the tire equator, and the tire for rough terrain travel according to any one of claims 1 to 9.

11. A tire for rough terrain travel having a tread portion, The tread portion has a specified tire rotation direction, The tread portion is provided with a crown block, a middle block located more outside in the tire axial direction than the crown block, and a groove portion located between the crown block and the middle block. The crown block is A tread surface, A first wall surface located on the leading side in the tire rotation direction, And a first edge at the intersection of the tread surface and the first wall surface. The first wall surface is inclined from the tread surface inward in the tire radial direction toward the trailing side in the tire rotation direction. The length of the groove portion in the tire axial direction is 5% to 70% of the length of the middle block in the tire axial direction. The tread surface of the crown block has a first point located most on the leading side in the tire rotation direction, a second point located most on the leading side on the tire equator in the tire rotation direction, and a third point located most on the trailing side on the tire equator in the tire rotation direction. In a plan view of the tread portion, at least a part of the middle block is located between a first virtual straight line passing through the first point and the second point, and a second virtual straight line obtained by translating the first virtual straight line onto the third point. The angle of the first virtual straight line with respect to the tire circumferential direction is 45 to 89 degrees. The middle block has 70% or more of the area of the tread surface of the middle block positioned between the first virtual straight line and the second virtual straight line. The middle block includes a middle main portion that is inclined toward the leading side in the tire rotation direction toward the outer side in the tire axial direction, and a middle protruding portion that extends from the middle main portion to the trailing side in the tire rotation direction. All of the middle protruding portions are positioned on the trailing side in the tire rotation direction from the second virtual straight line. Tire for rough terrain driving.

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