Tire for rough terrain

Abstract

To improve traction performance and steering stability on uneven ground. An uneven ground running tire (1) has a tread portion (2). A crown block (5), an intermediate block (6), and a groove portion (7) are provided in the tread portion (2). The crown block (5) includes a tread surface (10) and a first wall surface (11) located on a leading landing side in a tire rotation direction (R). The first wall surface (11) is inclined toward a trailing landing side in the tire rotation direction (R) as it moves from the tread surface (10) toward an inner side in a 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 intermediate block (6).

Description

Technical Field

[0001] This invention relates to tires for driving on uneven terrain. Background Technology

[0002] Patent Document 1 describes a pneumatic tire with multiple tread blocks in the tread area. These tread blocks are formed by inclined tread blocks, wherein the tread block walls on the first and last contact sides are inclined in a direction that causes both the first and last contact edges to advance towards the first contact side beyond the root of each tread block wall. This inclined tread block design provides high road excavation capability and excellent traction on uneven surfaces.

[0003] Patent Document 1: Japanese Patent No. 3384716

[0004] However, in recent years, there has been a demand for improved traction and handling stability on uneven surfaces. Summary of the Invention

[0005] The present invention was made in view of the actual situation described above, and its main objective is to provide a tire for driving on uneven terrain that improves traction and handling stability on uneven terrain.

[0006] The present invention is a tire for driving on uneven ground, having a tread portion, wherein the tread portion is designated in the tire rotation direction, and having a crown tread block, an intermediate tread block located axially outward of the crown tread block, and a groove located between the crown tread block and the intermediate tread block. The crown tread block includes a tread surface, a first wall surface on the first contact 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 toward the rear contact side in the tire rotation direction from the tread surface toward the radial direction inward. The axial length of the groove is 5% to 70% of the axial length of the intermediate tread block.

[0007] The tire for driving on uneven ground according to the present invention preferably includes a second wall surface located on the rear contact side in the direction of tire rotation and a second edge at the intersection of the tread surface and the second wall surface, wherein the second wall surface is inclined toward the rear contact side in the direction of tire rotation as it moves inward from the tread surface toward the tire radius direction.

[0008] The tire for driving on uneven ground according to the present invention preferably includes a first wall surface and a second wall surface, respectively, extending from the first edge and the second edge to 50% of the height of the tread block. The angle α of the first wall surface outer portion relative to the normal of the tread surface passing through the first edge is smaller than the angle β of the second wall surface outer portion relative to the normal of the tread surface passing through the second edge.

[0009] The tire for driving on uneven ground according to the present invention is preferably wherein the angle α is 45 degrees or less.

[0010] The tire for driving on uneven ground according to the present invention is preferably wherein the aforementioned angle β is 5 to 70 degrees.

[0011] The tire for driving on uneven ground according to the present invention preferably includes the outer side of the second wall surface comprising: a first portion extending from the second edge toward the inner side in the tire radius direction; and a second portion located at a position closer to the inner side in the tire radius direction than the first portion and inclined more gently than the first portion.

[0012] The tire for driving on uneven surfaces according to the present invention preferably has the following tread surface of the tread pattern blocks: a first point located on the first contact side closest to the direction of tire rotation; a second point located on the tire equator on the first contact side closest to the direction of tire rotation; and a third point located on the tire equator on the rear contact side closest to the direction of tire rotation. When the tread surface is viewed from above, at least a portion of the intermediate tread blocks are located between a first imaginary straight line passing through the first point and the second point, and a second imaginary straight line obtained by translating the first imaginary straight line to the third point.

[0013] The tire for driving on uneven ground according to the present invention is preferably wherein the angle of the first imaginary straight line relative to the tire circumference is 45 to 89 degrees.

[0014] The tire for driving on uneven ground according to the present invention is preferably wherein the tread pattern blocks cross the tire equator.

[0015] The tire for driving on uneven ground according to the present invention preferably has the tread blocks extending from both sides of the tire equator toward the tire axial direction toward the side that first touches the ground in the direction of tire rotation.

[0016] The tire for driving on uneven terrain of the present invention, by adopting the above-described structure, can improve traction performance and handling stability on uneven terrain. Attached Figure Description

[0017] Figure 1This is a radial cross-sectional view of a tire for driving on uneven terrain, according to an embodiment of the present invention.

[0018] Figure 2 yes Figure 1 A top view of the unfolded tread of the tire.

[0019] Figure 3 yes Figure 2 A-A sectional view.

[0020] Figure 4 yes Figure 2 Enlarged view of the tread pattern on the tire crown.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1…Tire for driving on uneven ground; 2…Tread; 5…Tread block; 6…Intermediate tread block; 7…Groove; 10…Tread surface; 11…First sidewall; La…Length of groove 7; Lm…Length of intermediate tread block. Detailed Implementation

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0024] Figure 1 This is a cross-sectional view of the tire radial axis (not shown) 1, which is used for driving on uneven terrain according to an embodiment of the present invention, in its normal state. Figure 2 This is a unfolded diagram of the tread section 2 of tire 1. (Example) Figure 1 as well as Figure 2 As shown, the tire 1 in this embodiment is a motorcycle tire.

[0025] The term "normal condition" refers to the unloaded state in which tire 1 is assembled onto a normal rim (illustration omitted) and filled with normal internal pressure. Unless otherwise specified, the dimensions of the tire and other components described below are values ​​measured under this normal condition.

[0026] "Standard rim" is a rim that specifies the size of each tire within a specification system that includes the specifications on which the tire is based. For example, JATMA is "standard rim", TRA is "design rim", and ETRTO is "measuring rim".

[0027] "Standard internal pressure" is the air pressure specified for each tire in the specification system, including the specifications on which tire 1 is based. If it is JATMA, it is "maximum air pressure". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it is "INFLATION PRESSURE".

[0028] In the cross-section described above, the outer surface of the tread portion 2 of the tire 1 in this embodiment is curved in an arc shape that protrudes outward in the radial direction of the tire. Furthermore, the tread portion 2 of the tire 1 has a directional pattern indicating the tire's rotation direction R.

[0029] In this embodiment, the tread portion 2 is provided with a crown tread block 5, an intermediate tread block 6 located on the outer side of the tire axial direction than the crown tread block 5, and a groove located between the crown tread block 5 and the intermediate tread block 6 (in this specification, this groove may be referred to as the "intermediate groove") 7.

[0030] Figure 3 yes Figure 2 A sectional view along line A-A. Line A-A extends along the circumference of the tire. For example... Figure 2 as well as Figure 3 As shown, the tread pattern block 5 of this embodiment includes a tread surface 10, a first wall surface 11 located on the side that first contacts the ground 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 the area that contacts the ground plane when the tire 1 in its normal state is loaded with a normal load for driving.

[0031] The aforementioned "regular load" refers to the load specified for each tire in the specification system, including the specification on which tire 1 is based. If it is JATMA, it is "maximum load capacity". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it is "LOAD CAPACITY".

[0032] The first wall 11 slopes towards the rear contact side in the tire rotation direction R, moving from the tread surface 10 toward the inner side in the tire radius direction. The tread blocks 5 with this first wall 11 cut through uneven road surfaces covered with mud, thereby generating high traction.

[0033] The axial length La of the groove 7 is 5% to 70% of the axial length Lm of the intermediate tread block 6. Since the length La of the groove 7 is less than 70% of the length Lm of the intermediate tread block 6, the excavated soil can be contained within a certain range, and the soil can be compacted and sheared, thus generating greater traction. Since the length La of the groove 7 is more than 5% of the length Lm of the intermediate tread block 6, the continued blockage of soil into the groove 7 after contact with the ground is suppressed. Therefore, during cornering and other maneuvers, the edges 5e and 6e of the groove 7 sides of the tread block 5 and intermediate tread block 6 can be effectively utilized, resulting in excellent handling stability.

[0034] In order for the above-mentioned function to be effective, the length La of the groove 7 is preferably 20% or more of the length Lm of the intermediate pattern block 6, more preferably 30% or more, more preferably 60% or less, and more preferably 50% or less.

[0035] In this embodiment, the tread portion 2 is provided with a shoulder tread block 8 located axially outside the intermediate tread block 6, and a groove 9 located between the shoulder tread block 8 and the intermediate tread block 6. The shoulder tread block 8 includes, for example, an outer edge 8e located at its position closest to the axial outer side of the tire. The outer edge 8e forms a tread end Te extending circumferentially along the tire.

[0036] In this embodiment, the tread portion 2 is formed by a linearly symmetrical pattern centered on the tire equator C. The tread blocks 5, for example, cross the tire equator C. The intermediate tread blocks 6 and the shoulder tread blocks 8 are respectively disposed on both sides of the tread blocks 5 along the tire axial direction. Furthermore, in this embodiment, each of the tread blocks 5, 6, and 8 is arranged at the same spacing in the tire circumferential direction.

[0037] like Figure 3 As shown, the tread pattern block 5 includes, for example, a second wall 13 located on the rear contact side in the tire rotation direction R, and a second edge 14 at the intersection of the tread 10 and the second wall 13.

[0038] In this embodiment, the second wall surface 13 is inclined towards the rear contact side in the tire rotation direction R, moving inward from the tread surface 10 towards the inner side in the tire radius direction. This second wall surface 13 increases the rigidity of the tread block 5 and suppresses the twisting of the tread block 5 during driving. As a result, the soil-digging effect is improved.

[0039] The first wall surface 11 and the second wall surface 13 each include an outer portion 16 and an outer portion 19 of the first wall surface extending from the first edge 12 and the second edge 14 to 50% of the tread block height H1 of the tread block 5, respectively. Furthermore, the angle α of the outer portion 16 of the first wall surface relative to the normal 10a of the tread surface 10 passing through the first edge 12 is formed to be smaller than the angle β of the outer portion 19 of the second wall surface relative to the normal 10b of the tread surface 10 passing through the second edge 14. Because angle α is smaller than angle β, the twisting of the tread block 5 during driving is significantly suppressed, thereby enabling more effective digging of the soil. When the outer portion 19 of the second wall surface extends, for example, in an arc shape or a stepped shape—in other words, when it does not extend in a straight line—angle β is determined by the angle between the inner end 19i of the outer portion 19 of the second wall surface in the tire radial direction and the imaginary straight line 19x passing through the second edge 14 and the normal 10b. Angle α is determined in the same way as angle β.

[0040] To ensure the above-mentioned effects are effective, the angle α can exceed 0 degrees, preferably 5 degrees or more, and more preferably 15 degrees or more. However, if the angle α is too large, the rigidity of the inner portion of the tread block 5 in the tire radius direction decreases, increasing the likelihood of tread block defects, cracks, etc. Therefore, it is preferable that the angle α is 45 degrees or less, and more preferably 35 degrees or less.

[0041] To improve the rigidity of the tread blocks 5, an angle β of 5 degrees or more is preferred, and more preferably 20 degrees or more is more desirable. If the angle β is too large, the distance between the tread blocks 5 arranged circumferentially on the tire increases, reducing the frequency of digging through the mud and potentially decreasing traction performance. Therefore, an angle β of 70 degrees or less is preferred, and more preferably 60 degrees or less is more desirable.

[0042] In order for the above-mentioned effects to be effective, the difference (β-α) between angle β and angle α is preferably 5 degrees or more, more preferably 10 degrees or more, more preferably 50 degrees or less, and more preferably 40 degrees or less.

[0043] The outer portion 16 of the first wall extends in a straight line from the first edge 12, for example. However, the outer portion 16 of the first wall is not limited to this form; for example, it may be formed as an arc shape that is recessed from the rear contact side of the tread block 5 in the tire rotation direction R.

[0044] In this embodiment, the outer side portion 19 of the second wall includes: a first portion 21 extending inward from the second edge 14 toward the tire radius direction; and a second portion 22 located inward in the tire radius direction than the first portion 21 and inclined gently inward than the first portion 21. The first portion 21 particularly helps to improve the rigidity of the portion of the tread block 5 on the tread surface 10 side, which experiences large forces, thereby improving traction performance. In this embodiment, the first portion 21 extends in a straight line. The first portion 21 and the second portion 22, for example, incline toward the rear contact side in the tire rotation direction R as they move inward toward the tire radius direction. In this embodiment, the first portion 21 and the second portion 22 are connected via an arcuate portion 23 protruding toward the first contact side in the tire rotation direction R.

[0045] The first wall surface 11 includes a first wall inner portion 17 connected to the outer side portion 16 of the first wall surface and located inside the outer side portion 16 in the tire radial direction. The second wall surface 13 includes a second wall inner portion 20 connected to the outer side portion 19 of the second wall surface and located inside the outer side portion 19 in the tire radial direction. The first wall inner portion 17 is, for example, formed as an arc shape recessed towards the rear contact side of the tread block 5 in the tire rotation direction R. The second wall inner portion 20 is, for example, formed as an arc shape protruding towards the first contact side of the tread block 5 in the tire rotation direction R. In this embodiment, the second wall inner portion 20 is formed as an arc with a radius of curvature larger than that of the first wall inner portion 17. The first wall inner portion 17 and the second wall inner portion 20 are not limited to this form.

[0046] Figure 4 This is an enlarged view of tread pattern block 5 and the center tread pattern block 6. (See image below.) Figure 4 As shown, in this embodiment, the tread blocks 5 extend from both sides of the tire equator C toward the tire axial direction toward the side that first touches the ground in the tire rotation direction R. These tread blocks 5 help to collect and compact excavated soil at the central side of the tread block 5 along the tire axial direction.

[0047] The tread surface 10 of the tread block 5 has: a first point 25, located on the side that makes the first contact with the ground closest to the tire's rotation direction R; a second point 26, located on the tire equator C on the side that makes the first contact with the ground closest to the tire's rotation direction R; and a third point 27, located on the tire equator C on the side that makes the last contact with the ground closest to the tire's rotation direction R. Furthermore, when viewed from above on the tread surface 2, at least a portion of the intermediate tread block 6 lies between a first imaginary straight line M1 passing through the first point 25 and the second point 26, and a second imaginary straight line M2 obtained by translating the first imaginary straight line M1 onto the third point 27. Therefore, since the intermediate tread block 6 inhibits the discharge of soil excavated by the tread block 5 from the trench 7 and other areas, traction performance is further improved. In order for this function to be effective, preferably more than 70% of the area Am of the tread surface 6a of the intermediate pattern block 6 is located between the first imaginary straight line M1 and the second imaginary straight line M2, and preferably more than 80% of the area Am of the tread surface 6a of the intermediate pattern block 6 is located between the first imaginary straight line M1 and the second imaginary straight line M2.

[0048] Preferably, the angle θ1 of the first hypothetical straight line M1 relative to the tire circumference is 45 to 89 degrees. Since the angle θ1 is 45 degrees or more, it exerts a large shear force on the soil. Since the angle θ1 is less than 89 degrees, it suppresses the escape of soil excavated by the tread blocks 5 towards the outer side of the tire axial direction. Based on this viewpoint, the angle θ1 is more preferably 60 degrees or more, further preferably 65 degrees or more, more preferably less than 80 degrees, and even more preferably less than 75 degrees.

[0049] In this embodiment, the tread block 5 includes a tread protrusion 30 extending circumferentially across the second edge 14. The tread block 5 includes, for example, the tread protrusion 30 and a tread main portion 31 formed across the tire equator C. The tread protrusion 30 is located on both sides of the tire equator C. This tread protrusion 30, for example, further suppresses the tread block 5 from twisting towards the rear contact side in the tire rotation direction R upon contact with the ground.

[0050] When viewed from above, the tread protrusion 30 has a quadrilateral shape with a circumferential length Lb greater than the axial length Le. This tread protrusion 30 effectively enhances the aforementioned effect. In this embodiment, the tread protrusion 30 is formed as a parallelogram. The tread protrusion 30 may also be rectangular, for example. For example, the outer surface 30a of the tread protrusion 30 in the radial direction of the tire is located between the tire equator C and the first point 25 of the tread pattern block 5.

[0051] Preferably, the tire circumferential length Lb of the crown protrusion 30 is at least 1.0 times the tire circumferential length Ld of the edge 5e of the crown tread block 5, more preferably at least 1.3 times, more preferably less than 3.0 times, and more preferably less than 2.5 times. Furthermore, preferably, the tire axial length Le of the crown protrusion 30 is at least 1.0 times the tire axial length Lc of the crown tread block 5. Figure 2 The percentage of the tread protrusion 30 is 5% or more, more preferably 7% or more, more preferably 13% or less, and more preferably 11% or less. Furthermore, the circumferential length Lb of the tread protrusion 30 is preferably 2.5 times or more, more preferably 3.0 times or more, more preferably 4.5 times or less, and more preferably 4.0 times or less.

[0052] In this embodiment, the outer surface 30a of the crown protrusion 30 in the tire radial direction includes a lateral edge 33a disposed on the first contact side in its tire rotation direction R and extending along the tire axial direction, and a pair of longitudinal edges 33b, 33b extending circumferentially on both sides of its tire axial direction. Preferably, the outer surface 30a of the crown protrusion 30 in the tire radial direction is disposed at a position further outward in the tire radial direction than the outer surface 31a of the crown main portion 31 (same as the tread 10), or at the same position as the outer surface 31a of the crown main portion 31 in the tire radial direction. This crown protrusion 30 improves traction performance in both straight-line and cornering driving due to the lateral edge 33a and the pair of longitudinal edges 33b. The crown protrusion 30 and the crown main portion 31 are distinguished, for example, by a recess 32 that is recessed inward in the tire radial direction from the outer surface 31a of the crown main portion 31. In this embodiment, when viewed from above, the recess 32 is shaped to hold the crown protrusion 30, in a roughly U-shape or roughly C-shape.

[0053] In this embodiment, the main portion 31 of the tire crown is formed in a V-shape that extends from both sides of the tire equator C toward the tire axial direction toward the first contact side in the tire rotation direction R.

[0054] Preferably, the axial length Lc of the tread block 5 is 20% or more of the tread width TW, more preferably 25% or more, more preferably 40% or less, and more preferably 35% or less. Furthermore, preferably, the circumferential length Ld of the edge 5e of the tread block 5 is 15% or more of the axial length Lc of the tread block 5, more preferably 20% or more, more preferably 35% or less, and more preferably 30% or less. The tread width TW is the axial distance between the tread ends Te and Te when the tread portion 2 is unfolded into a flat surface.

[0055] The intermediate tread block 6 includes, for example, an intermediate main portion 35 that is inclined toward the first contact side of the tire rotation direction R as it moves outward toward the tire axial direction; and an intermediate protrusion 36 that extends from the intermediate main portion 35 toward the rear contact side of the tire rotation direction R.

[0056] The central main portion 35 is, for example, L-shaped, comprising an equal-length portion 35A of the same length in the tire circumference, and a length-enlarging portion 35B connected to the equal-length portion 35A, whose circumferential length increases outward toward the tire axial direction. "Same length" means that the difference (S-s) between the maximum and minimum circumferential lengths of the equal-length portion 35A is within 10% of the maximum value S. In this embodiment, the equal-length portion 35A is located on the side that makes contact with the ground first, closer to the tire rotation direction R than the second imaginary straight line M2. In this embodiment, the length-enlarging portion 35B crosses the second imaginary straight line M2 and is located on both sides of the tire circumference.

[0057] The outer surface 36a of the central protrusion 36 in the tire radius direction is positioned, for example, on the outer side of the central main portion 35 in the tire radius direction (same as the tread 6a) in the tire radius direction, or at the same position as the outer surface 35a of the central main portion 35 in the tire radius direction. This central protrusion 36 improves traction performance during straight-line and cornering driving.

[0058] While not particularly limited, it is preferred that the axial length Lm of the tire of the intermediate tread block 6 is 5% or more of the tread width TW, more preferably 10% or more, more preferably 20% or less, and more preferably 15% or less.

[0059] The preferred tread rubber for forming these tread blocks 5, 6, and 8 is 2G ( Figure 1 The complex elastic modulus E* (shown) is 10–40 MPa. In this specification, the complex elastic modulus E* is a value measured using a viscoelastic spectrometer manufactured by Iwamoto Manufacturing Co., Ltd. under the conditions shown below, in accordance with JIS-K6394.

[0060] Initial strain: 1%

[0061] Amplitude: ±2%

[0062] Frequency: 10Hz

[0063] Deformation mode: Stretch

[0064] Temperature: 30℃

[0065] The above describes a particularly preferred embodiment of the invention, but the invention is not limited to the illustrated embodiments and can be implemented in various ways. The front wheel tires have all identical tread patterns.

[0066]

Example

[0067] Based on the specifications in Table 1, a prototype with... Figure 2 The test tires were rear wheel tires for motorcycles designed for use on uneven terrain. Furthermore, the traction and handling stability of each tire were tested. The common specifications and testing methods for each tire are described below.

[0068] Vehicle used: 450cc off-road motorcycle racing vehicle

[0069] Tire sizes (front and rear): 80 / 100-21, 120 / 80-19

[0070] Wheel rim sizes (front and rear): 21×1.60, 19×2.15

[0071] Internal pressure: 80 kPa

[0072] The testing method is as follows.

[0073] <Traction performance and handling stability>

[0074] The traction and handling stability of the test vehicles on uneven terrain with mud were assessed using rider sensory evaluations. "Torsion performance" was determined by assessing the smoothness of acceleration during straight-line travel and cornering. "Handling stability" was determined by assessing the stability of the vehicles, including handlebar operation, during straight-line travel and cornering. All tests were scored out of 10. The test results are shown in Table 1.

[0075] Table 1

[0076]

[0077] The test results show that, compared with the tires of the comparative example, the tires of the embodiment have improved traction and handling stability on uneven surfaces.

Claims

1. A tire for driving on uneven terrain, having a tread pattern, characterized in that, The tread section is designated to indicate the tire's rotation direction. The tread portion includes tread blocks, an intermediate tread block located axially outside the tread blocks, and a groove between the tread blocks and the intermediate tread blocks. The tread pattern includes: the area that contacts the ground when the tire is in a normal state and is subjected to a normal load, i.e., the tread surface; a first wall surface located on the side that contacts the ground first in the direction of tire rotation; and a first edge at the intersection of the tread surface and the first wall surface. The first wall surface slopes inward from the tread surface toward the rear contact side in the tire rotation direction, towards the inner side in the tire radius direction. The axial length of the groove is 5% to 70% of the axial length of the intermediate tread block. The tread surface of the tire tread block has: a first point located on the side that makes the first contact with the ground, closest to the direction of tire rotation; a second point located on the tire equator on the side that makes the first contact with the ground, closest to the direction of tire rotation; and a third point located on the tire equator on the side that makes the last contact with the ground, closest to the direction of tire rotation. When viewed from above, at least a portion of the central tread pattern blocks lie between a first imaginary straight line passing through the first and second points, and a second imaginary straight line obtained by translating the first imaginary straight line to the third point. The angle between the first hypothetical straight line and the tire's circumference is 45-89 degrees. More than 70% of the area of ​​the tread surface of the intermediate patterned block lies between the first imaginary straight line and the second imaginary straight line.

2. The tire for driving on uneven terrain according to claim 1, characterized in that, The tread pattern block includes: a second wall surface located on the rear contact side in the direction of tire rotation, and a second edge at the intersection of the tread surface and the second wall surface. The second wall surface tilts towards the rear contact side in the tire rotation direction from the inside of the tread surface in the tire radius direction.

3. The tire for driving on uneven terrain according to claim 2, characterized in that, The first wall surface and the second wall surface each include: an outer portion of the first wall surface extending from the first edge and the second edge to 50% of the height of the tread block of the tire crown pattern, and an outer portion of the second wall surface. The angle α of the outer portion of the first wall surface relative to the normal of the tread surface passing through the first edge is smaller than the angle β of the outer portion of the second wall surface relative to the normal of the tread surface passing through the second edge.

4. The tire for driving on uneven terrain according to claim 3, characterized in that, The angle α is less than 45 degrees.

5. The tire for driving on uneven terrain according to claim 3 or 4, characterized in that, The angle β is 5 to 70 degrees.

6. The tire for driving on uneven terrain according to claim 3 or 4, characterized in that, The outer portion of the second wall includes: a first portion extending inward from the second edge toward the tire radius; and a second portion located inward in the tire radius direction than the first portion and gently inclined than the first portion.

7. The tire for driving on uneven terrain according to any one of claims 1 to 4, characterized in that, The angle between the first imaginary straight line and the tire circumference is 45-80 degrees.

8. The tire for driving on uneven terrain according to claim 7, characterized in that, The angle between the first imaginary straight line and the tire circumference is 45 to 75 degrees.

9. The tire for driving on uneven terrain according to any one of claims 1 to 4, 8, characterized in that, The tread blocks cross the tire equator.

10. The tire for driving on uneven terrain according to any one of claims 1 to 4, 8, characterized in that, The tread blocks extend from the tire equator toward both sides of the tire axis toward the side that first touches the ground in the direction of tire rotation.

11. A tire for driving on uneven terrain, having a tread pattern, characterized in that, The tread section is designated to indicate the tire's rotation direction. The tread portion includes tread blocks, an intermediate tread block located axially outside the tread blocks, and a groove between the tread blocks and the intermediate tread blocks. The tread pattern includes: the area that contacts the ground when the tire is in a normal state and is subjected to a normal load, i.e., the tread surface; a first wall surface located on the side that contacts the ground first in the direction of tire rotation; and a first edge at the intersection of the tread surface and the first wall surface. The first wall surface slopes inward from the tread surface toward the rear contact side in the tire rotation direction, towards the inner side in the tire radius direction. The axial length of the groove is 5% to 70% of the axial length of the intermediate tread block. The tread surface of the tire tread block has: a first point located on the side that makes the first contact with the ground, closest to the direction of tire rotation; a second point located on the tire equator on the side that makes the first contact with the ground, closest to the direction of tire rotation; and a third point located on the tire equator on the side that makes the last contact with the ground, closest to the direction of tire rotation. When viewed from above, at least a portion of the central tread pattern blocks lie between a first imaginary straight line passing through the first and second points, and a second imaginary straight line obtained by translating the first imaginary straight line to the third point. The angle between the first hypothetical straight line and the tire's circumference is 45-89 degrees. More than 70% of the surface area of ​​the intermediate patterned block lies between the first imaginary straight line and the second imaginary straight line. The intermediate tread block includes: an intermediate main portion that is inclined toward the first contact side in the tire rotation direction as it moves outward toward the tire axial direction; and an intermediate protrusion that extends from the intermediate main portion toward the rear contact side in the tire rotation direction.

Images