Tire for rough terrain

Abstract

The invention improves the traction performance on uneven ground. The invention is an uneven ground running tire (1) having a tread portion (2). A crown block (5) is provided in the tread portion (2). The crown block (5) includes a crown block main body (10) formed in a V shape convex toward the rear ground contact side in the tire rotation direction (N), and a crown fin portion (11) protruding from the crown block main body (10) toward the rear ground contact side in the tire rotation direction (N). The crown fin portion (11) is only two.

Description

Technical Field

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

[0002] Patent Document 1 describes a tire for driving on uneven surfaces with tread blocks on the tread portion. The tread blocks include a main body and three finned portions protruding circumferentially from the main body. These finned portions help improve traction performance.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-084554

[0004] If the aforementioned tires are used on muddy or muddy roads, mud can easily get stuck between the tire crown fins, and the stuck mud is difficult to remove, thus tending to reduce traction. Summary of the Invention

[0005] This disclosure is made in view of the actual situation described above, and its main purpose is to provide tires for driving on uneven terrain that can improve traction performance on uneven surfaces.

[0006] This disclosure discloses a tire for driving on uneven terrain with a tread pattern, wherein the tread pattern is designated with a tire rotation direction, and a plurality of tread blocks are provided on the tire equator in the tread pattern, each of the plurality of tread blocks comprising: a tread block body formed in a convex V-shape facing the rear contact side in the tire rotation direction; and tread fin portions protruding from the tread block body toward the rear contact side in the tire rotation direction, each of the tread blocks having only 2 of the aforementioned tread fin portions.

[0007] By adopting the above structure, the tire for driving on uneven terrain disclosed herein can improve traction performance on uneven terrain. Attached Figure Description

[0008] Figure 1 This is a radial cross-sectional view of a tire for driving on uneven terrain, according to one embodiment of the present disclosure.

[0009] Figure 2 It is an expansion Figure 1 The top view obtained from the surface of the tire.

[0010] Figure 3 yes Figure 2 Enlarged view of the tread pattern on the tire crown.

[0011] Figure 4 yes Figure 2 Enlarged view of the tread pattern on the tire crown.

[0012] Figure 5 yes Figure 2 Enlarged view of the tread pattern on the tire crown.

[0013] Figure 6 yes Figure 5 A-A sectional view.

[0014] Figure 7 yes Figure 5 Sectional view along line B-B.

[0015] Figure 8 yes Figure 2 An enlarged view of the central patterned block.

[0016] Figure 9 yes Figure 2 An enlarged view of the tire shoulder tread pattern.

[0017] Explanation of reference numerals in the attached figures:

[0018] 1…Tire for driving on uneven ground; 2…Tread surface; 5…Tread block; 10…Tread block body; 11…Tread fin; N…Tire rotation direction. Detailed Implementation

[0019] Hereinafter, an embodiment of the present disclosure will be described based on the accompanying drawings.

[0020] Figure 1 This is a cross-sectional view of a tire (hereinafter simply referred to as "tire") 1 for driving on uneven terrain according to an embodiment of this disclosure. Figure 1 This shows a cross-section of the tire's meridian, including the tire's axis of rotation (not shown), when the pneumatic tire is in its normal state. Figure 2 This is a unfolded view of the tread portion 2 of tire 1. The tire 1 disclosed herein is suitable for two-wheeled motorcycles, but can also be used in passenger cars and heavy-duty vehicles. Furthermore, the tire 1 disclosed herein can also be applied to non-pneumatic tires that are not filled with compressed air.

[0021] The term "normal condition" refers to the unloaded state in which tire 1 is assembled on 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.

[0022] "Standard rim" is a rim specified for each tire within a specification system that includes the specifications on which tire 1 is based. For example, if it is JATMA, it is "standard rim"; if it is TRA, it is "Design Rim"; and if it is ETRTO, it is "Measuring Rim".

[0023] "Standard internal pressure" refers to the air pressure specified for each tire in the specification system, including the specification 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".

[0024] In this embodiment, the tread portion 2 is curved into an arc shape in the tire's radial cross-section, with its outer surface bulging outwards radially from the tire. Furthermore, the tread portion 2 has a directional pattern that specifies the tire's rotation direction (hereinafter referred to simply as "rotation direction") N.

[0025] In the tread portion 2 of this embodiment, a plurality of tread blocks 5 are provided on the tire equator C. Each of the plurality of tread blocks 5 includes: a tread block body 10, which is formed into a convex V-shape facing the rear contact side in the rotation direction N; and a tread fin portion 11, which protrudes from the tread block body 10 toward the rear contact side in the rotation direction N. Such tread blocks 5 suppress the tilting of the tread fin portion 11 toward the rear contact side in the rotation direction N of the tread block body 10 when it touches the ground, thus enabling the exertion of basic digging force in the mud and improving traction performance.

[0026] Each tread block 5 has only two tread fin portions 11. As a result, there is only one area in each tread block 5 where soil is easily clogged (i.e., the area between the tread fin portions 11, 11), reducing soil clogging and thus maximizing the edge effect of the tread block body 10.

[0027] The tread portion 2 includes, for example, a plurality of intermediate tread blocks 6 located on the outer side of each crown tread block 5 along the tire axial direction, and a plurality of shoulder tread blocks 7 located on the outer side of each intermediate tread block 6 along the tire axial direction. In this embodiment, the intermediate tread blocks 6 are disposed on both sides of the crown tread blocks 5 along the tire axial direction. Each tread block 5 to 7 is divided by the tread base 2R.

[0028] Figure 3 This is an enlarged view of tread pattern block 5. (See image below.) Figure 3As shown, the tread block body 10 includes a tread surface 12, a first-contact tread block edge 13 on the first-contact side of the tread surface 12 in the rotation direction N, and a rear-contact tread block edge 14 on the rear-contact side of the tread surface 12 in the rotation direction N. The tread block body 10 also includes a pair of circumferential edges 15, 15 connecting the first-contact tread block edge 13 and the rear-contact tread block edge 14 and extending along the tire circumference. The first-contact tread block edge 13, the rear-contact tread block edge 14, and the circumferential edges 15 are connected to the tread block wall surface 8 of the tread block body 10, which extends radially outward from the tread base 2R of the tire. In this embodiment, the circumferential edges 15 extend in a straight line and parallel to the tire circumference. Each circumferential edge 15 forms the outer end 10e of the tread block body 10 in the tire axial direction. In this specification, the term "extending in parallel" includes, of course, the case where the angle difference between the two sides is 0 degrees, and also the case where the absolute value of the angle difference is less than 10 degrees.

[0029] In this embodiment, the first-contact tread block edge 13 and the rear-contact tread block edge 14 are inclined from the center of the tread block width direction toward the two outer sides of the tread block width direction toward the rear-contact side in the rotation direction N. The first-contact tread block edge 13 and the rear-contact tread block edge 14 each have a rear-contact end 13e and 14e located on the rearmost contact side in the rotation direction N. Each rear-contact end 13e and 14e is located, for example, on the tire equator C.

[0030] The angle θ1 of the edge 13 of the first contact side tread block relative to the tire axial direction is preferably 10 degrees or more, more preferably 15 degrees or more, and preferably 45 degrees or less, more preferably 35 degrees or less. The angle θ1 of the edge 13 of the first contact side tread block is the angle of the line segment connecting the rear contact end 13e and the intersection of the edge 13 of the first contact side tread block and the circumferential edge 15.

[0031] Figure 4 This is an enlarged view of tread pattern block 5. (See image below.) Figure 4 As shown, the edge 13 of the first-contact tread block, from each circumferential edge 15 to the rear contact end 13e, is continuously inclined in the same direction relative to the tire axial direction, toward the rear contact side in the rotation direction N. The edge 13 of the first-contact tread block includes a first outer portion 13a communicating with the circumferential edge 15, a first inner portion 13b including the rear contact end 13e, and a first intermediate portion 13c connecting the first outer portion 13a and the first inner portion 13b. The first intermediate portion 13c is inclined at a larger angle relative to the tire axial direction than the first outer portion 13a and the first inner portion 13b. The first outer portion 13a and the first intermediate portion 13c extend, for example, in a straight line. The first inner portion 13b extends, for example, in a V-shape.

[0032] The difference (θ1c - θ1a) between the angle θ1a of the first outer portion 13a and the angle θ1c of the first middle portion 13c is preferably 10 degrees or more, more preferably 15 degrees or more, and preferably 35 degrees or less, more preferably 30 degrees or less. The difference (θ1c - θ1b) between the angle θ1b of the first inner portion 13b and the angle θ1c of the first middle portion 13c is preferably 10 degrees or more, more preferably 15 degrees or more, and preferably 35 degrees or less, more preferably 30 degrees or less.

[0033] The rear contact patch edge 14 includes an inner edge portion 14A extending axially inward from the connection portion K between the tread patch body 10 and the tread fin portion 11, and an outer edge portion 14B extending axially outward from the connection portion K. The inner edge portion 14A includes, for example, a rear contact end 14e. The inner edge portion 14A extends in a V-shape, for example. In this embodiment, the outer edge portion 14B communicates with the circumferential edge 15. The outer edge portion 14B extends in a straight line, for example.

[0034] When viewed from above, in this embodiment, the crown fin portion 11 is formed as a parallelogram. The crown fin portion 11 includes, for example, an outer edge 11e in the tread block width direction, an inner edge 11i in the tread block width direction, a first contact edge 11a on the first contact side in the rotational direction N, and a rear contact edge 11b on the rear contact side in the rotational direction N. The outer edge 11e and the inner edge 11i extend, for example, parallel to the tire circumferential direction. The first contact edge 11a is, for example, located on the first contact side in the rotational direction N, closer to the rear contact side tread block edge 14. The first contact edge 11a and the rear contact edge 11b extend, for example, parallel to the outer edge portion 14B. The inner edge 11i, the outer edge 11e, the first contact edge 11a, and the rear contact edge 11b form the outer surface 11A of the crown fin portion 11 facing the outer side of the tire radially.

[0035] In this embodiment, the outer surface 11A is located on the outer side of the tread surface 12 of the tread block body 10, further outward from the radial direction of the tire (e.g., Figure 6 (As shown). The outer surface 11A may also be located in the same position in the radial direction of the tire as the tread surface 12 of the tread block body 10.

[0036] The outer edges 11e of each of the two tread fin portions 11 in the width direction of the tread block are located on the inner side of the tread block width direction at the two ends 10e, 10e of the tread block body 10 on the tire axis. As a result, the deformation of the tread fin portions 11 is maintained, and the mud blocking the tread fin portions 11, 11 is smoothly discharged, thus enabling the edge effect of the tread block body 10 to be better utilized.

[0037] like Figure 3As shown, the axial spacing La between the two tread fin portions 11 is preferably 30% to 50% of the axial width W1 of the tread block body 10. Since the spacing La is 30% or more of the width W1 of the tread block body 10, mud can be smoothly discharged. Since the spacing La is 50% or less of the width W1 of the tread block body 10, tipping of the tread block body 10 can be effectively suppressed. According to this viewpoint, the spacing La is more preferably 35% or more of the width W1 of the tread block body 10, and even more preferably 45% or less.

[0038] The axial distance Lb between the outer edge 11e of the tread fin portion 11 and one end 10e of the tread block body 10 is preferably 15% or more, more preferably 20% or more, and more preferably 35% or less, and more preferably 30% or less, of the width W1 of the tread block body 10. This ensures the deformation of the tread fin portion 11, thereby improving the mud removal effect.

[0039] The axial width W2 of the tread fin portion 11 is preferably 5% or more, more preferably 10% or more, and more preferably 20% or less, and more preferably 15% or less. Since the width W2 of the tread fin portion 11 is 5% or more of the width W1 of the tread fin portion 10, the tilting of the tread fin portion 10 can be effectively suppressed. Since the width W2 of the tread fin portion 11 is 20% or less of the width W1 of the tread fin portion 10, excessive increase in the rigidity of the tread fin portion 11 can be suppressed, thereby maintaining soil clearance.

[0040] To prevent the tread block body 10 from tipping over, the protruding length Lc of the tread fin portion 11 extending from the tread block body 10 in the tire circumferential direction is preferably 50% or more of the tire circumferential length L1 of the tread block body 10. If the protruding length Lc of the tread fin portion 11 is too large, the soil clearance may be reduced. Therefore, the protruding length Lc of the tread fin portion 11 is more preferably 60% or more of the length L1 of the tread block body 10, and preferably 150% or less, more preferably 110% or less.

[0041] Figure 5 This is an enlarged view of tread pattern block 5. (See image below.) Figure 5 As shown, a shallow groove 18 is formed at the connection point K between the tread block body 10 and the tread fin portion 11 to promote partial deformation of the tread fin portion 11 on the side near the connection point K. This shallow groove 18 helps to smoothly drain the soil clogging between the tread fin portions 11.

[0042] The shallow groove 18 communicates with the inner edge portion 14A and the outer edge portion 14B in a manner that surrounds the connecting portion K. The shallow groove 18 extends, for example, along the outer edge 11e, the inner edge 11i, and the first contact edge 11a. This shallow groove 18 makes the tread fin portion 11 and the tread block body 10 appear independent of each other, thereby increasing the deformation of the tread fin portion 11 and further improving traction performance on uneven ground. In this embodiment, the shallow groove 18 extends in a U-shape protruding towards the first contact side in the rotation direction N.

[0043] Figure 6 yes Figure 5 A sectional view along line A-A. For example... Figure 6 As shown, the groove depth d1 of the shallow groove 18 is preferably 5% or more, more preferably 10% or more, and preferably 25% or less, more preferably 20% or less, of the tread block height H1 of the tire crown tread block 5. Furthermore, as... Figure 5 As shown, the width W3 of the shallow groove 18 is preferably 2% or more, more preferably 5% or more, and preferably 15% or less, more preferably 10% or less, of the width W1 of the tread block body 10. This effectively achieves the aforementioned function and maintains the rigidity of the tread fin portion 11 and the tread block body 10, thereby ensuring their high shear force.

[0044] The circumferential distance Ld between the end 18e of the first contact side of the shallow groove 18 in the rotation direction N and the edge 14 of the tread block on the rear contact side is preferably less than 60% of the length L1 of the tread block body 10. This maintains the circumferential rigidity of the tread block body 10, thus effectively suppressing the tipping of the tread block 5 upon contact with the ground.

[0045] Although not specifically limited, the width W1 of the tread block body 10 is preferably 20% or more, more preferably 25% or more, and preferably 40% or less, more preferably 35% or less, of the tread unfolded width TW. The tread unfolded width TW is the axial distance between the tread ends Te and Te when the tread portion 2 is unfolded into a plane (e.g., ...). Figure 2 (As shown).

[0046] Figure 7 yes Figure 5 A cross-sectional view along line B-B. For example... Figure 7 As shown, the tread block wall 8 of the tire crown tread block body 10 includes a first side wall 16 extending radially inward from the edge 13 of the tread block on the first contact side towards the tire, and a second side wall 17 extending radially inward from the edge 14 of the tread block on the rear contact side towards the tire. The first side wall 16 includes an outer portion 16a and an inner portion 16b in a longitudinal section.

[0047] The outer portion 16a extends in a straight line from the edge 13 of the first-contact tread block towards the radially inward side of the tire, and extends obliquely towards the rear-contact side in the direction of rotation N, compared to the tread normal n perpendicular to the edge 13 of the first-contact tread block. The inner portion 16b connects the outer portion 16a to the tread base 2R in an arc-shaped curve. This first sidewall 16 can penetrate the road surface deeply. In this specification, the term "straight line" includes, of course, a straight line with an infinite radius of curvature, as well as an arc with a radius of curvature of 200 mm or more.

[0048] In this embodiment, the inner portion 16b is formed with a single radius of curvature. Since this inner portion 16b can mitigate stress concentration acting on it, traction performance can be further improved. Alternatively, the inner portion 16b can also be formed with multiple arcs of varying radii of curvature.

[0049] The second sidewall 17 includes, for example, a first portion 17a, a second portion 17b, and a third portion 17c. The first portion 17a extends radially inward from the rear contact patch edge 14 towards the tire. The second portion 17b is connected to the first portion 17a and is more gently inclined than the first portion 17a. The third portion 17c connects the second portion 17b to the tread base 2R. In this embodiment, the first portion 17a and the second portion 17b extend in a straight line. The third portion 17c is curved in an arc shape. The third portion 17c is, for example, formed as an arc shape that is recessed towards the first contact side in the rotation direction N.

[0050] Figure 8 This is a magnified view of the area around the central patterned block 6. (For example...) Figure 8 As shown, the intermediate tread block 6 includes an intermediate tread block body 20 that is inclined from the inner side of the tire axis toward the outer side toward the first contact side in the rotation direction N and is a parallelogram, and an intermediate fin portion 21 that protrudes from the intermediate tread block body 20 toward the rear contact side in the rotation direction N.

[0051] The main body 20 of the intermediate tread block includes a tread surface 22, a first-landing side intermediate edge 23 defining the rotation direction N of the tread surface 22, and a rear-landing side intermediate edge 24 defining the rear-landing side of the tread surface 22. The main body 20 of the intermediate tread block also includes a pair of circumferential intermediate edges 25 extending from both ends of the first-landing side intermediate edge 23 toward the rear-landing side in the rotation direction N.

[0052] A pair of circumferential intermediate edges 25 are formed by an inner edge portion 25a that is adjacent to the tread block 5 in the tire axial direction and an outer edge portion 25b that is adjacent to the shoulder tread block 7 in the tire axial direction. The circumferential intermediate edges 25 extend in a straight line, for example.

[0053] For example, two intermediate fin portions 21 are provided in the intermediate pattern block body 20. The intermediate fin portion 21 is composed of an outer intermediate fin portion 21A connected to the outer edge portion 25b and an inner intermediate fin portion 21B disposed on the inner side of the outer intermediate fin portion 21A closer to the tire axis.

[0054] The outer intermediate fin portion 21A is directly connected to the intermediate tread block body 20. The outer edge 26 of the outer intermediate fin portion 21A along the tire axial direction and the outer edge portion 25b are formed by a straight line.

[0055] The inner intermediate fin portion 21B is connected to the intermediate tread block body 20 via the intermediate shallow groove 30. The inner edge 27 and inner edge portion 25a of the inner intermediate fin portion 21B in the tire axial direction are formed in a straight line across the intermediate shallow groove 30. Since the inner intermediate fin portion 21B is deformed by the intermediate shallow groove 30, the mud blocked between the two intermediate fin portions 21 can be smoothly discharged. In this embodiment, the groove edge 30a extending along the long side of the intermediate shallow groove 30 and disposed on the first-landing side in the rotation direction N forms the rear-landing side intermediate edge 24.

[0056] The width W4 of the shallow groove 30 is preferably 80% or more, more preferably 90% or more, and more preferably 125% or less, and more preferably 110% or less, of the shallow groove 18 of the tread block 5. The depth of the shallow groove 30 (not shown) is preferably 5% or more, more preferably 10% or more, and more preferably 20% or less, and more preferably 15% or less, of the tread block height (not shown), of the tread block body 20. The width W5 of the tread block body 20 is preferably 5% or more, more preferably 10% or more, and more preferably 25% or less, and more preferably 20% or less, of the tread width TW.

[0057] Figure 9 This is a top view of tire shoulder tread block 7. (Example) Figure 9As shown, the shoulder tread block 7 is formed as a quadrilateral when viewed from above. In this embodiment, the shoulder tread block 7 is formed as a trapezoid. The tread surface 7a of the shoulder tread block 7 includes an outer edge 41, an inner edge 42, a rear contact side edge 43, and a first contact side edge 44. The outer edge 41 extends circumferentially along the tire axis, for example, outside the tire axis of the tread surface 7a. In this embodiment, the outer edge 41 forms the tread end Te. The inner edge 42 extends circumferentially along the tire axis, for example, inside the tire axis of the tread surface 7a. In this embodiment, the rear contact side edge 43 connects the inner edge 42 and the outer edge 41 and extends parallel to the tire axis. The rear contact side edge 43 of this embodiment defines the rear contact side of the rotation direction N of the shoulder tread block 7. In this embodiment, the first contact side edge 44 connects the inner edge 42 and the outer edge 41 and is inclined relative to the tire axis. In this embodiment, the first-to-ground edge 44 defines the first-to-ground side of the rotation direction N of the tire shoulder tread block 7.

[0058] In this embodiment, the shoulder tread block 7 has a shoulder groove 45. When viewed from above, the shoulder groove 45 extends in a V-shape. This shoulder groove 45 can promote the deformation of the shoulder tread block 7, thereby smoothly expelling the mud that is blocking the space between the shoulder tread block 7 and the intermediate tread block 6.

[0059] The shoulder groove 45 includes a circumferential portion 46 extending along the tire circumference and an axial portion 47 extending along the tire axis. The circumferential portion 46 extends at an angle of less than 45 degrees relative to the tire circumference. The axial portion 47 is inclined at an angle of more than 45 degrees relative to the tire circumference.

[0060] In this embodiment, the circumferential portion 46 extends parallel to the tire circumferential direction from the rear contact edge 43 toward the first contact side in the rotational direction N, and terminates within the shoulder tread block 7. In this embodiment, the axial portion 47 extends from the inner edge 42 toward the outer side in the tire axial direction and connects to the end of the circumferential portion 46. In this embodiment, the axial portion 47 extends parallel to the first contact edge 44. This shallow shoulder groove 45 further promotes the deformation of the shoulder tread block 7.

[0061] The width W6 of the shoulder shallow groove 45 is preferably 5% or more, more preferably 10% or more, and more preferably 25% or less, and more preferably 20% or less, of the tire axial width W7 of the shoulder tread block 7. The depth of the shoulder shallow groove 45 (not shown) is preferably 5% or more, more preferably 10% or more, and more preferably 20% or less, and more preferably 15% or less, of the tread block height (not shown). The width W7 of the shoulder tread block 7 is preferably 5% or more, more preferably 7% or more, and more preferably 20% or less, and more preferably 15% or less, of the tread unfolded width TW.

[0062] The tread rubber 2G (e.g., forming 5-7 tread blocks) is used to form this pattern. Figure 1 The rubber hardness (as shown) is preferably 70 degrees or higher, and more preferably 90 degrees or lower. In this specification, the rubber hardness is based on the A hardness of a hardness tester measured by JIS-K6253 at 23°C.

[0063] The above details the particularly preferred embodiments of this disclosure, but this disclosure is not limited to the embodiments shown in the figures and can be implemented in various ways.

[0064]

Example

[0065] Based on the specifications in Table 1, a prototype with... Figure 2 These are rear wheel tires for motorcycles designed for use on uneven terrain. Furthermore, the traction, braking, and overall performance of each test tire were tested. The front wheel tires were identical in all examples. The common specifications and test methods for all test tires are described below.

[0066] Vehicle used: 450cc off-road racing motorcycle

[0067] Tire sizes (front and rear): 80 / 100-21, 120 / 80-19

[0068] Wheel rim dimensions (front and rear): 21×1.60, 19×2.15

[0069] Internal pressure: 80 kPa

[0070] The testing method is as follows.

[0071] <Traction performance, braking performance, overall performance>

[0072] The traction and braking performance of the test vehicles were evaluated by testing the driver's senses when driving on uneven surfaces with mud. Here, "traction performance" was evaluated by testing the smoothness of acceleration during straight-line driving and cornering, using the driver's senses. "Braking performance" was evaluated by testing the stability of deceleration during straight-line driving and cornering, using the driver's senses. "Overall performance" was evaluated by testing the stability of acceleration and deceleration during straight-line driving and cornering, using the driver's senses. All tests were scored out of 10.

[0073] The test results are shown in Table 1.

[0074] Table 1

[0075]

[0076] The test results show that, compared to the comparative example tires, the tires of the embodiment exhibit improved traction performance on uneven surfaces. Furthermore, compared to the comparative example tires, the tires of the embodiment demonstrate improved braking performance.

[0077] [Postscript]

[0078] This disclosure includes the following methods.

[0079] [This disclosure 1]

[0080] A tire for driving on uneven surfaces has a tread portion, wherein the tread portion is designated with a tire rotation direction. On the tread portion, a plurality of tread blocks are provided on the tire equator. Each of the plurality of tread blocks includes: a tread block body, which is formed into a convex V-shape facing the rear contact side in the tire rotation direction; and tread fin portions, which protrude from the tread block body towards the rear contact side in the tire rotation direction. Each of the tread blocks has only two of the tread fin portions.

[0081] [This disclosure 2]

[0082] In the tire for driving on uneven ground as described in this disclosure 1, the outer edge of each of the two crown fin portions in the tread block width direction is located inside the tread block width direction at both ends of the tire axial direction of the crown tread block body.

[0083] [This disclosure 3]

[0084] In the tire for driving on uneven terrain described in this disclosure 1 or 2, the axial distance between the two tread fin portions is 30% to 50% of the axial width of the tread block body.

[0085] [This disclosure 4]

[0086] In any of the tires for driving on uneven terrain described in any of the present disclosures 1 to 3, the axial width of each of the aforementioned tread fin portions is 5% to 20% of the axial width of the aforementioned tread block body.

[0087] [This disclosure 5]

[0088] In any of the tires for driving on uneven surfaces described in any of the present disclosures 1 to 4, the protruding length of the crown fin portion protruding from the tread block body in the tire circumferential direction is 50% or more of the tire circumferential length of the tread block body.

[0089] [This disclosure 6]

[0090] In any of the tires for driving on uneven terrain described in any of the present disclosures 1 to 5, a shallow groove is formed at the connection between the tread block body and the tread fin portion to promote deformation of the portion of the tread fin portion on the side of the connection.

[0091] [This disclosure 7]

[0092] In the tire for driving on uneven surfaces described in this disclosure 6, the tread block body includes a tread surface and a rear contact side tread block edge that defines the rotation direction of the tread surface. The rear contact side tread block edge includes: an inner edge portion that extends from the connecting portion toward the inner side of the tire axis; and an outer edge portion that extends from the connecting portion toward the outer side of the tire axis. The shallow groove communicates with the inner edge portion and the outer edge portion in a manner that surrounds the connecting portion.

[0093] [This disclosure is 8]

[0094] In the tire for driving on uneven terrain described in this disclosure 6 or 7, the groove depth of the shallow groove is 5% to 25% of the height of the tread block body of the tread pattern block.

[0095] [This disclosure is number 9]

[0096] In any of the tires for driving on uneven terrain described in any of the present disclosures 6 to 8, the width of the shallow groove is 2% to 15% of the axial width of the tread block body.

[0097] [This disclosure is 10]

[0098] In any of the tires for driving on uneven surfaces described in any of the present disclosures 6 to 9, the tread block body includes a tread surface and a rear contact side tread block edge on the rear contact side defining the rotation direction of the tread surface, and the circumferential distance between the end of the shallow groove on the first contact side in the tire rotation direction and the rear contact side tread block edge is 60% or less of the circumferential length of the tread block body.

[0099] [This disclosure is number 11]

[0100] In any of the tires for driving on uneven surfaces described in any of the present disclosures 1 to 10, the main body of the tread pattern includes a tread surface and a first-contact side tread block edge that defines the rotation direction of the tread surface, wherein the angle of the first-contact side tread block edge relative to the tire axial direction is 10 to 45 degrees.

Claims

1. A tire for driving on uneven terrain, having a tread pattern, characterized in that, The tread section specifies the tire's rotation direction. On the tread surface, multiple tread blocks are provided on the tire equator. The plurality of tread pattern blocks respectively include: The main body of the tread pattern is formed in a convex V-shape on the rear contact side facing the direction of tire rotation; and The tread fin portion protrudes from the tread block body toward the rear contact side in the direction of tire rotation. Each of the aforementioned tread pattern blocks has only two of the aforementioned tread fin portions. The tread block body includes a tread surface, a first-contact tread block edge on the first-contact side of the tread surface defining the tire rotation direction, a rear-contact tread block edge on the rear-contact side of the tread surface defining the tire rotation direction, and a pair of circumferential edges connecting the first-contact tread block edge and the rear-contact tread block edge and extending along the tire circumference. The edge of the first-contact tread block, from its circumferential edge to the rearmost contact end located in the tire's rotation direction, is inclined in the same direction relative to the tire's axial direction towards the rear contact side in the tire's rotation direction. The edge of the first-landing patterned block includes a first outer portion communicating with each circumferential edge, a first inner portion including the rear-landing end and extending in a V-shape, and a first middle portion connecting the first outer portion and the first inner portion. The angle θ1c of the first middle portion relative to the tire axis is greater than the angle θ1a of the first outer portion relative to the tire axis and the angle θ1b of the first inner portion relative to the tire axis.

2. The tire for driving on uneven terrain according to claim 1, characterized in that, The outer edge of each of the two tread fin portions in the width direction of the tread block is located inside the tread block width direction at both ends of the tire axial direction of the tread block body.

3. The tire for driving on uneven terrain according to claim 1 or 2, characterized in that, The axial spacing between the two tread fin portions is 30% to 50% of the axial width of the tread block body.

4. The tire for driving on uneven terrain according to claim 1 or 2, characterized in that, The axial width of each of the tread fin portions is 5% to 20% of the axial width of the tread block body.

5. The tire for driving on uneven terrain according to claim 1 or 2, characterized in that, The protruding length of the crown fin portion extending from the crown tread block body toward the tire circumference is more than 50% of the tire circumference length of the crown tread block body.

6. The tire for driving on uneven terrain according to claim 1 or 2, characterized in that, A shallow groove is formed at the connection between the tread block body and the tread fin portion to promote deformation of the portion of the tread fin portion on the side of the connection.

7. The tire for driving on uneven terrain according to claim 6, characterized in that, The rear contact patch edge includes: an inner edge portion extending from the connecting portion toward the inner side of the tire axial direction; and an outer edge portion extending from the connecting portion toward the outer side of the tire axial direction. The shallow groove communicates with the inner edge and the outer edge in a manner that surrounds the connecting portion.

8. The tire for driving on uneven terrain according to claim 6, characterized in that, The depth of the shallow groove is 5% to 25% of the height of the tread block body of the tire crown tread block.

9. The tire for driving on uneven terrain according to claim 6, characterized in that, The width of the shallow groove is 2% to 15% of the axial width of the tire tread block body.

10. The tire for driving on uneven terrain according to claim 6, characterized in that, The circumferential distance between the end of the shallow groove on the first contact side of the tire in the direction of tire rotation and the edge of the tread block on the second contact side is less than 60% of the circumferential length of the tread block body.

11. The tire for driving on uneven terrain according to claim 1 or 2, characterized in that, The angle between the edge of the first-contact side tread block and the tire axial direction is 10 to 45 degrees.

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