Tire

Abstract

To provide a tire that can be suppressed from side slipping while being enhanced in wear resistance.SOLUTION: A tire 1 includes a pair of shoulder block rows 4 and 4 and a plurality of crown blocks 5. The crown blocks 5 are constituted of a plurality of first crown blocks 7 and a plurality of second crown blocks 8. The plurality of second crown blocks 8 is arranged so that second crown block pairs 9 in which two second crown blocks 8 are adjacently arranged in a tire axial direction appear repeatedly in a tire circumferential direction. Each first crown block 7 is arranged between the second crown block pairs 9 adjacently arranged in the tire circumferential direction. The first crown block 7 has a tread face 7a in a horizontally-long shape in which the maximum length L1 is smaller than the maximum width W1. The second crown block 8 has a tread face 8a in a vertically-long shape in which the maximum length L2 is larger than the maximum width W2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tire. [Background technology]

[0002] Patent Document 1 listed below describes a tire having a plurality of middle blocks provided in a crown region. The plurality of middle blocks are longer in the circumferential direction of the tire than in the axial direction of the tire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-82904 A Summary of the Invention [Problem to be solved by the invention]

[0004] The tire of Patent Document 1 is said to have increased circumferential rigidity and improved wear resistance. However, there is room for improvement in suppressing lateral slippage (lateral flow) during driving with such a tire.

[0005] The present invention has been devised in view of the above problems, and has as its main object to provide a tire capable of suppressing sideslip while improving wear resistance. [Means for solving the problem]

[0006] a tire including a tread portion, the tread portion including a pair of shoulder block rows and a plurality of crown blocks arranged between the pair of shoulder block rows, the crown blocks being composed of a plurality of first crown blocks and a plurality of second crown blocks, the plurality of second crown blocks being arranged so that second crown block pairs, each of which has two of the second crown blocks arranged adjacent to each other in the tire axial direction so as to overlap in the tire circumferential direction, repeatedly appear in the tire circumferential direction, the plurality of first crown blocks being arranged between each of the second crown block pairs adjacent to each other in the tire circumferential direction, each of the plurality of first crown blocks having a horizontally elongated tread surface whose maximum circumferential length is smaller than the maximum axial width of the tire, and each of the plurality of second crown blocks having a vertically elongated tread surface whose maximum circumferential length is greater than the maximum axial width of the tire. Effect of the Invention

[0007] By employing the above-described configuration, the tire of the present invention can suppress sideslip while improving wear resistance. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view of a tread portion of a tire according to one embodiment of the present invention. [Diagram 2] FIG. 4 is a plan view of a first crown block. [Diagram 3] 2, and FIG. 4B is a cross-sectional view taken along line BB in FIG. [Figure 4] FIG. 13 is a plan view of a second crown block pair. [Diagram 5] FIG. [Figure 6] 6 is a cross-sectional view taken along line CC in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings include exaggerated expressions and expressions different from the dimensional ratio of the actual structure in order to facilitate understanding of the present invention. In addition, when there are multiple embodiments, the same or common elements are given the same reference numerals throughout the specification, and duplicated explanations are omitted.

[0010] 1 is a plan view of a tread portion 2 of a tire 1 showing one embodiment of the present invention. The present invention is preferably used as a pneumatic tire for SUVs that is also expected to run on off-road surfaces including muddy roads and rocky roads. However, the present invention may also be applied to pneumatic tires for light trucks and heavy loads, and non-pneumatic tires that do not have pressurized air filled inside the tire.

[0011] In this specification, unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured in a normal state. In the case of a pneumatic tire, the "normal state" refers to a state in which the tire 1 is mounted on a normal rim (not shown) and inflated to a normal internal pressure with no load. In the case of a tire for which no standards are established or a non-pneumatic tire, the normal state refers to a standard usage state according to the intended use of the tire, in which the tire is not mounted on a vehicle and no load is applied.

[0012] A "genuine rim" is a rim that is defined for each tire by a standard system that includes the standard on which tire 1 is based, such as a "standard rim" in the case of JATMA, a "Design Rim" in the case of TRA, and a "Measuring Rim" in the case of ETRTO.

[0013] "Normal internal pressure" is the air pressure set for each tire by each standard in the standard system including the standard on which tire 1 is based, and is the "maximum air pressure" in the case of JATMA, the maximum value listed in the table "TIRE LOAD LIMITSAT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and the "INFLATION PRESSURE" in the case of ETRTO.

[0014] The tread portion 2 includes a pair of shoulder block rows 4, 4 and a plurality of crown blocks 5 disposed between the pair of shoulder block rows 4.

[0015] The crown block 5 is made up of a plurality of first crown blocks 7 and a plurality of second crown blocks 8.

[0016] The second crown blocks 8 are arranged so that second crown block pairs 9, each of which has two second crown blocks 8 adjacent to each other in the axial direction so as to overlap in the tire circumferential direction, are repeatedly arranged in the tire circumferential direction. The term "overlapping in the tire circumferential direction" means that the tire circumferential length Ld of the tire circumferential overlapping portion D of the two second crown blocks 8 overlaps by 60% or more of the maximum circumferential length L2 of the second crown blocks 8 in the tire circumferential direction, and also includes overlapping by 65% ​​or more.

[0017] Each of the second crown blocks 8 has a vertically elongated tread surface 8a whose maximum circumferential length L2 is greater than its axial maximum width W2. Such second crown blocks 8 exhibit basic wear resistance. In this specification, the "tread surface" refers to a surface that comes into contact with a flat surface (described later) under a normal load condition (described later).

[0018] The first crown blocks 7 are arranged between adjacent second crown block pairs 9 in the tire circumferential direction. In other words, the first crown blocks 7 and the second crown block pairs 9 are arranged alternately in the tire circumferential direction. In this specification, the term "alternately in the tire circumferential direction" refers to a mode in which the tire circumferential length Ls of the tire circumferential overlap portion S between the second crown block pair 9 and the first crown block 7 is 3% or less of the tread width TW. Note that the second crown block pair 9 and the first crown block 7 may not overlap at all in the tire circumferential direction (not shown).

[0019] The tread width TW is the axial length between the tread ends Te. The tread end Te is defined as the axially outermost ground contact position of the tire under normal load. The "normal load condition" refers to a state in which the tire 1 under normal load is placed on a flat surface with a camber angle of 0 degrees.

[0020] In the case of a pneumatic tire for which various standards are established, the "normal load" is the load that is established for each tire by each standard in the standard system including the standard on which the tire is based, and is the "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. In addition, in the case of a tire for which various standards are not established, the "normal load" refers to the maximum load that can be applied when using the tire according to the above-mentioned standards.

[0021] Each of the first crown blocks 7 has a tread surface 7a with a horizontally elongated shape in which the maximum length L1 in the tire circumferential direction is smaller than the maximum width W1 in the tire axial direction. Since such a first crown block 7 has a large rigidity in the tire axial direction, it suppresses lateral slippage during driving. The first crown block 7 of this embodiment can suppress the occurrence of lateral slippage, especially when driving off-road with a side camber. In addition, since one first crown block 7 is disposed between each pair of second crown blocks 9 adjacent in the tire circumferential direction, blocks with high rigidity in the tire circumferential direction and blocks with high rigidity in the tire axial direction are alternately disposed in the tire circumferential direction. As a result, the effect of suppressing the frequency and magnitude (degree) of lateral slippage (hereinafter sometimes referred to as "lateral slippage resistance performance") and the effect of improving wear resistance performance are alternately exerted, so that it is possible to suppress lateral slippage while improving wear resistance performance.

[0022] The ratio (L1 / W1) of the maximum circumferential length L1 of the horizontally elongated tread surface 7a to the maximum axial width W1 of the horizontally elongated tread surface 7a is preferably 0.4 or more, more preferably 0.5 or more, more preferably 0.8 or less, and even more preferably 0.7 or less. Since the ratio (L1 / W1) is 0.4 or more, the rigidity of the first crown block 7 in the circumferential direction of the tire is ensured, and the wear resistance performance is maintained. Since the ratio (L1 / W1) is 0.8 or less, the skid resistance performance is improved. In addition, the maximum width W1 of the horizontally elongated tread surface 7a is preferably 25% or more of the tread width TW, more preferably 30% or more, more preferably 45% or less, and even more preferably 40% or less.

[0023] In order to effectively exert the above-mentioned action, the ratio (L2 / W2) of the maximum circumferential length L2 of the elongated tread surface 8a to the maximum axial width W2 of the tire is preferably 1.3 or more, more preferably 1.4 or more, even more preferably 1.5 or more, preferably 2.0 or less, more preferably 1.9 or less, and even more preferably 1.8 or less. The maximum width W2 of the elongated tread surface 8a is preferably 10% or more of the tread width TW, more preferably 15% or more, more preferably 30% or less, and even more preferably 25% or less.

[0024] The absolute value |A1-A2| of the difference between the area A1 of the tread surface 7a of the first crown block 7 and the area A2 of the tread surface 8a of each second crown block 8 is preferably 40% or less of the smaller of the areas A1 and A2. This reduces the difference between the area A1 of the tread surface 7a of the first crown block 7 and the area A2 of the tread surface 8a of the second crown block 8, and reduces the difference in rigidity between the crown blocks 7 and 8 in the tire circumferential direction, thereby maintaining high wear resistance. From this perspective, the absolute value |A1-A2| is more preferably 35% or less of the smaller of the areas A1 and A2, and even more preferably 30% or less. In FIG. 1, the area A1 of the tread surface 7a and the area A2 of the tread surface 8a are indicated by hatching. In this embodiment, the area A1 of the tread surface 7a is larger than the area A2 of the tread surface 8a.

[0025] FIG. 2 is a plan view of the first crown block 7. As shown in FIG. 2, each of the first crown blocks 7 includes a first crown block edge 7e that defines the tread surface 7a. In the tread plan view, the first crown block edge 7e includes a recess 11 including a V-shaped edge 11e recessed inwardly of the tread surface 7a. Such a recess 11 improves off-road running stability because the V-shaped edge 11e exerts a shear force on a muddy road surface and a scratching force on a rocky road surface or the like. The recess 11 of this embodiment has a vertex 11t located at the innermost side (centroid side) of the tread surface 7a.

[0026] In this embodiment, the angle α1 between the V-shaped edges 11e is set to 80 to 120 degrees. Since the angle α1 is 80 degrees or more, the concentration of the load acting on the apex 11t can be reduced, and the occurrence of chipping, which is a chipping of the block (first crown block 7), can be suppressed. Since the angle α1 is 120 degrees or less, the mud on the muddy road surface can be smoothly collected in the recess 11, and the shear force can be increased. From this viewpoint, the angle α1 is preferably 90 degrees or more and 110 degrees or less. In this specification, the angle α1 is the angle between the virtual straight lines v1, v1 connecting the apex 11t and two points e1, e1 located on both sides of the apex 11t. The two points e1, e1 are points on the V-shaped edge 11e separated by 5 mm from the apex 11t.

[0027] Two recesses 11 are provided in the first crown block 7. This allows the above-mentioned effects to be exerted effectively.

[0028] The first crown block edge 7e is formed including a pair of first lateral edges 13, 13 extending in the tire axial direction and a pair of first longitudinal edges 14, 14 connecting both ends 13e of each first lateral edge 13. The first longitudinal edges 14 extend in the tire circumferential direction. In this specification, the term "extending in the tire axial direction" refers to an aspect in which the edge extends at an angle of less than 45 degrees with respect to the tire axial direction. In this specification, the term "extending in the tire circumferential direction" refers to an aspect in which the edge extends at an angle of 45 degrees or more with respect to the tire axial direction. In this embodiment, each first lateral edge 13 extends in the tire axial direction continuously between both ends 13e. In this embodiment, each first longitudinal edge 14 extends in the tire circumferential direction continuously between both ends.

[0029] In this embodiment, the recesses 11 are provided in each of the first lateral edges 13. Such recesses 11 exert shear force against skidding and can more effectively improve skid resistance. The recesses 11 are formed, for example, in a horizontally elongated shape in which the maximum width Wr in the tire axial direction is greater than the maximum length Lr in the tire circumferential direction. The recesses 11 in this embodiment are provided away from both ends 13e of the first lateral edges 13.

[0030] The V-shaped edge 11e of the recess 11 is composed of, for example, a first edge 11a inclined in a first direction with respect to the tire axial direction, and a second edge 11b connected to the first edge 11a and inclined in the opposite direction to the first edge 11a. The edge 11e of this embodiment is formed so that the first edge 11a and the second edge 11b are connected via a vertex 11t. In this embodiment, the first edge 11a and the second edge 11b extend linearly. Also, the first edge 11a and the second edge 11b are inclined continuously at the same angle with respect to the tire axial direction, for example. The angle α2 of the first edge 11a with respect to the tire axial direction and the angle α3 of the second edge 11b with respect to the tire axial direction are formed, for example, between 30 degrees or more and less than 45 degrees. In this specification, the term "straight line" includes not only a state in which the edges 11a, 11b extend in a straight line, but also a state in which the edges 11a, 11b extend in an arc with a curvature radius of 100 mm or more.

[0031] The recessed portion 11 may be provided, for example, in the first vertical edge 14. In this case, the recessed portion 11 increases the shear force in the tire circumferential direction, thereby improving the traction performance and braking performance (hereinafter referred to as "traction performance, etc.").

[0032] The maximum width Lr of the recess 11 is preferably 0.35 times or more, more preferably 0.40 times or more, more preferably 0.55 times or less, and even more preferably 0.50 times or less, of the maximum width W1 (shown in FIG. 1) of the first crown block 7. Since the maximum width Lr of the recess 11 is 0.35 times or more of the maximum width W1, a large shear force can be exerted. Since the maximum width Lr of the recess 11 is 0.55 times or less of the maximum width W1, a high rigidity of the first crown block 7 can be ensured.

[0033] Fig. 3(A) is a cross-sectional view taken along line AA in Fig. 2. As shown in Fig. 3(A), each of the first crown blocks 7 includes a first block wall surface 7s extending from a first crown block edge 7e inward in the tire radial direction and outward of the tread surface 7a. The first block wall surface 7s is inclined at an angle θ1 of 10 to 20 degrees with respect to a tread normal n that is erected at the first crown block edge 7e. Such a first block wall surface 7s increases the rigidity of the first crown block 7, which is useful for improving wear resistance and traction performance on off-road roads.

[0034] Fig. 4 is a plan view of the second crown block pair 9. As shown in Fig. 4, the second crown block pair 9 is formed in a point-symmetric shape such that one of the second crown blocks 8 overlaps with the other second crown block 8 when rotated 180 degrees at any point on the tire equator C.

[0035] The second crown block 8 includes a second crown block edge 8e that defines the tread surface 8a, and a second block wall surface 8s that extends from the second crown block edge 8e radially inward and outward of the tread surface 8a. In this embodiment, each of the second crown block edges 8e of the second crown block pair 9 includes inner block edges 20 that face each other. In other words, the crown longitudinal grooves 23 are formed by the inner block edges 20 of the second crown block pair 9. The second crown block edge 8e further includes, for example, an outer block edge 21 that is spaced apart from the inner block edge 20 in the tire axial direction, and a pair of lateral block edges 22 that connect the inner block edge 20 and the outer block edge 21 on both sides in the tire circumferential direction. The outer block edge 21 extends, for example, in the tire circumferential direction. Each lateral block edge 22 extends in the tire axial direction.

[0036] The inner block edge 20 of this embodiment includes a first inclined portion 25 including a first end 20e in the longitudinal direction of the inner block edge 20 and inclined toward a first side (lower left side in the figure) with respect to the tire circumferential direction, and a second inclined portion 26 connected to the first inclined portion 25 and inclined toward the opposite side from the first side. The inner block edge 20 also includes a third inclined portion 27 connected to the second inclined portion 26 and inclined toward the first side. The third inclined portion 27 of this embodiment includes a second end 20i in the longitudinal direction of the inner block edge 20. The first inclined portion 25, the second inclined portion 26, and the third inclined portion 27 are inclined in the same direction with respect to the tire circumferential direction, and in this embodiment, they are inclined at the same angle with respect to the tire circumferential direction (extend directly). In this embodiment, the second crown block pair 9 is such that the first inclined portion 25 of one second crown block 8 faces the third inclined portion 27 of the other second crown block 8. For example, the second inclined portion 26 of one second crown block 8 faces the second inclined portion 26 of the other second crown block 8. Furthermore, in this embodiment, the third inclined portion 27 of one second crown block 8 faces the first inclined portion 25 of the other second crown block 8. In other words, the crown longitudinal grooves 23 are formed to extend in a zigzag shape. Such crown longitudinal grooves 23 exert high shear strength off-road.

[0037] The angle α4 of the first inclined portion 25 with respect to the tire circumferential direction is preferably smaller than the angle α5 of the second inclined portion 26 with respect to the tire circumferential direction. As a result, the first inclined portion 25 located outside the second inclined portion 26 in the tire circumferential direction makes it easier to discharge mud on a muddy road surface that comes into contact with the second inclined portion 26 and the first inclined portion 25 by utilizing the rolling motion of the tire 1, and also exerts an edge effect in the tire axial direction to improve the lateral slip resistance performance. In addition, the second inclined portion 26 exerts a high shear force in the tire circumferential direction to improve traction performance, etc. From this viewpoint, the angle α4 of the first inclined portion 25 is preferably 20 degrees or more, more preferably 25 degrees or more, more preferably 40 degrees or less, and even more preferably 35 degrees or less. In addition, the angle α5 of the second inclined portion 26 is preferably 40 degrees or more, more preferably 45 degrees or more, more preferably 60 degrees or less, and even more preferably 55 degrees or less.

[0038] It is desirable that the angle α6 of the third inclined portion 27 with respect to the tire circumferential direction is the same as the angle α4 of the first inclined portion 25. The term "same" as used above includes not only a case where the absolute value |α4-α6| of the difference between the angle α6 of the third inclined portion 27 and the angle α4 of the first inclined portion 25 is 0 degrees, but also a case where the absolute value |α4-α6| is 10 degrees or less.

[0039] Fig. 3(B) is a cross-sectional view taken along line BB in Fig. 4. As shown in Fig. 3(B), each of the second crown blocks 8 has a second block wall surface 8s that is inclined at an angle θ2 of 10 to 20 degrees with respect to a tread normal n that is perpendicular to the second crown block edge 8e. Even with such a second block wall surface 8s, the rigidity of the second crown block 8 can be increased.

[0040] As shown in FIG. 1, each of the multiple crown blocks 5 includes a linearly extending shallow groove 15. The shallow groove 15 appropriately reduces the rigidity of each crown block 7, 8 to improve the enveloping property and improve the running performance on rocky road surfaces. Moreover, the shallow groove 15 can improve the traction performance and the like off-road while suppressing the occurrence of chipping, as compared with sipes. In this specification, the sipe is a cut-like recess with a width of less than 1.5 mm. A groove including the shallow groove 15 is a recess-like recess with a groove width of 1.5 mm or more. In this specification, the shallow groove refers to a groove having a groove depth of 50% or less of the block heights H1, H2 (shown in FIG. 3) of each crown block 7, 8.

[0041] Two shallow grooves 15 are provided in each of the first crown blocks 7, and one shallow groove 15 is provided in each of the second crown blocks 8. In this embodiment, the area A1 of the tread surface 7a of the first crown block 7 is larger than the area A2 of the tread surface 8a of the second crown block 8. Therefore, the difference in rigidity between the first crown blocks 7 (two blocks) and the second crown block 8 (one block) is smaller, and the difference in the amount of wear between the first crown block 7 and the second crown block 8 is smaller.

[0042] In the first crown block 7 having a horizontally long tread surface 7a, the shallow grooves 15 extend in the tire circumferential direction. In the second crown block 8 having a vertically long tread surface 8a, the shallow grooves 15 extend in the tire axial direction. Such shallow grooves 15 maintain the rigidity in the tire circumferential direction and the rigidity in the tire axial direction of the first crown block 7 and the second crown block 8 respectively, and improve the wear resistance performance.

[0043] As shown in FIG. 2, each shallow groove 15 of the first crown block 7 is connected to the recess 11 of the first crown block 7. Such shallow grooves 15 appropriately reduce the rigidity of the recess 11, promote the deformation of the recess 11 due to grounding and non-grounding during running, and help remove mud on the muddy road surface and stones on the rocky road surface that are fitted into the recess 11. In the present embodiment, the shallow grooves 15 of the first crown block 7 are arranged so as to be displaced from the apex 11t. Such shallow grooves 15 ensure the rigidity near the apex 11t and increase the shearing force on the mud by the apex 11t.

[0044] The two shallow grooves 15 of the first crown block 7 extend parallel to each other. Such shallow grooves 15 reduce the change in the rigidity in the tire axial direction of the first crown block 7 and effectively exhibit the enveloping property. In this specification, the "parallel" includes not only the case where the absolute value |α8 - α9| of the difference between the angles α8 and α9 of each shallow groove 15 with respect to the tire axial direction is 0 degree, but also the aspect where it is 10 degrees or less. The two shallow grooves 15 of the first crown block 7 extend, for example, so as to connect the respective first horizontal edges 13. Further, the shallow grooves 15 extend parallel to the first vertical edge 14.

[0045] As shown in FIG. 4, the shallow groove 15 of the second crown block 8 is connected to the intersection position K of the second inclined portion 26 and the third inclined portion 27. Such a shallow groove 15 promotes the deformation due to running at the intersection position K where the mud on the muddy road surface tends to stay, and facilitates the discharge of the mud. The shallow groove 15 of the second crown block 8 connects the inner block edge 20 and the outer block edge 21. In this specification, the shallow grooves 15 of each second crown block pair 9 extend parallel to each other.

[0046] The groove depth D1 (shown in FIG. 3) of the shallow groove 15 provided in each of the first crown block 7 and the second crown block 8 is preferably 30% or less of the block height H2 of each of the second crown blocks 8, more preferably 25% or less. Since the groove depth D1 of each shallow groove 15 is 30% or less of the block height H2, the rigidity of the crown block 5 is maintained high and the occurrence of chipping can be suppressed. If the groove depth D1 of the shallow groove 15 is too small, the envelope property may not be improved. For this reason, the groove depth D1 of the shallow groove 15 is preferably 5% or more of the block height H2, more preferably 10% or more. From the same viewpoint, the groove width Wa of each shallow groove 15 is preferably 5% or more of the maximum width W2 (shown in FIG. 1) of each of the second crown blocks 8, more preferably 7% or more, more preferably 15% or less, and more preferably 13% or less. In this embodiment, the block height H2 of the second crown block 8 is the same as the block height H1 of the first crown block 7 (shown in FIG. 3).

[0047] The crown block 5 of the present embodiment is not provided with any grooves or sipes other than the shallow grooves 15. Such a crown block 5 has high wear resistance and chipping resistance.

[0048] Fig. 5 is a plan view of a shoulder block row 4. Fig. 5 shows the shoulder block row 4 on the right side of Fig. 1. As shown in Fig. 5, each of a pair of shoulder block rows 4 includes a plurality of shoulder blocks 10 aligned in the tire circumferential direction. Each of the plurality of shoulder blocks 10 includes a first shoulder block 30 having a tread surface 30a that straddles the tread end Te on the inside and outside in the tire axial direction, and a second shoulder block 31 having a tread surface 31a that is arranged only on the inside of the tread end Te in the tire axial direction.

[0049] Each of the shoulder blocks 10 includes a shoulder block edge 10e that defines the tread surface 10a and a shoulder block wall surface 10s that extends radially inward from the shoulder block edge 10e. The shoulder block edge 10e includes a pair of lateral block edges 33, 33 that extend in the tire axial direction and a vertical block edge 34 that connects the inner ends 33i of the pair of lateral block edges 33 in the tire axial direction and extends in the tire circumferential direction.

[0050] The angle α10 of the pair of lateral block edges 33 with respect to the tire axial direction is 40 degrees or less. Such lateral block edges 33 have high circumferential rigidity and improve wear resistance. In addition, the lateral block edges 33 suppress collapse of the shoulder blocks 10 during off-road driving, and increase shear force against muddy road surfaces and cutting force against rocky road surfaces, improving off-road driving stability.

[0051] Each of the shoulder blocks 10 is preferably a plain block that is not provided with sipes (not shown). In the present embodiment, the shoulder blocks 10 are not provided with grooves, including shallow grooves, other than sipes. As a result, even when driving off-road with a side camber, the shoulder blocks 10 have high rigidity and come into contact with the ground, providing excellent traction performance, etc.

[0052] In order to effectively exert the above-mentioned effect, the maximum axial width W3 of each of the multiple shoulder blocks 10 is desirably 20% or more of the tread width TW (shown in FIG. 1), more desirably 25% or more, preferably 35% or less, and even more desirably 30% or less.

[0053] FIG. 6 is a cross-sectional view taken along line C-C of FIG. 5. As shown in FIG. 6, the shoulder block wall surface 10s is inclined at an angle θ3 of 10 to 20 degrees with respect to the tread normal n erected on the shoulder block edge 10e. Such a shoulder block wall surface 10s enhances the rigidity of the shoulder block 10 and exhibits the effects of improving the wear resistance performance and reducing the lateral slip of the block.

[0054] As shown in FIG. 1, the tread portion 2 of the present embodiment includes a four-block portion Xa in which the shoulder blocks 10 on both sides in the tire axial direction and the second crown block pair 9 are located on the tire axial direction line Y. Further, the tread portion 2 of the present embodiment includes a three-block portion Xb in which the shoulder blocks 10 on both sides in the tire axial direction and the first crown block 7 are located on the tire axial direction line Y. Thus, the tread portion 2 of the present embodiment is formed of the four-block portion Xa or the three-block portion Xb, and a five-block portion (not shown) in which five blocks are located on the tire axial direction line Y is not formed.

[0055] The land ratio of the tread portion 2 is preferably 40% or more, more preferably 45% or more, preferably 60% or less, and more preferably 55% or less. Since the land ratio of the tread portion 2 is 40% or more, the rigidity of each shoulder block row 4 and each crown block 5 is ensured, and the wear resistance performance is maintained high. Since the land ratio of the tread portion 2 is 60% or less, mud and the like on a muddy road can be largely scraped out between each shoulder block row 4 and each crown block, so that the running stability performance off-road can be enhanced. The land ratio is the ratio of the total area of the tread surfaces of the respective blocks to the area of the tread surface of a virtual tread portion in which all the recesses between the respective blocks and the grooves (shallow grooves in the present embodiment) provided in the respective blocks are filled.

[0056] 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.

Example

[0057] Pneumatic tires having the basic pattern shown in Figure 1 were manufactured and tested for their wear resistance and skid resistance. The test method and common specifications are as follows. Tire size: 35×12.50R20LT Rim: 10.0JJ x 20 Tire pressure: 450kPa

[0058] <Wear resistance> A test driver got into the test vehicle equipped with the prototype tire and drove it on a test course with a dry asphalt road surface. The test driver visually evaluated the wear state of the tread after the drive. The results are expressed as a score based on Comparative Example 1 being 100, with a higher score indicating less wear and better wear resistance. Test vehicle: 4700cc four-wheel drive vehicle Test tire mounting position: All wheels

[0059] <Slip resistance> A test driver got into the test vehicle equipped with the prototype tire and drove it on an off-road test course. The frequency and magnitude (level) of skidding during driving were evaluated by the test driver's senses. The results were expressed as a score based on Comparative Example 1 being 100, with a higher score indicating a lower frequency and magnitude of skidding and better skid resistance. The test results are shown in Table 1.

[0060] [Table 1]

[0061] As a result of the test, it is understood that the tires of the examples have improved wear resistance and suppressed skidding compared to the tires of the comparative examples.

[0062] [Note] The present invention includes the following aspects.

[0063] [Invention 1] A tire including a tread portion, The tread portion includes a pair of shoulder block rows and a plurality of crown blocks disposed between the pair of shoulder block rows, The crown block includes a plurality of first crown blocks and a plurality of second crown blocks, the plurality of second crown blocks are arranged such that second crown block pairs, each of which includes two second crown blocks arranged adjacent to each other in the tire axial direction so as to overlap each other in the tire circumferential direction, are repeatedly arranged in the tire circumferential direction, The first crown blocks are disposed between the second crown block pairs adjacent to each other in the tire circumferential direction, Each of the plurality of first crown blocks has a tread surface that is elongated in a circumferential direction and has a maximum circumferential length that is smaller than a maximum axial width of the tire, Each of the second crown blocks has a tread surface having an elongated shape whose maximum circumferential length is greater than its maximum axial width. tire. [Invention 2] The ratio (L1 / W1) of the maximum length L1 in the tire circumferential direction to the maximum width W1 in the tire axial direction of the horizontally elongated tread surface is 0.4 to 0.8, The tire according to invention 1, wherein a ratio (L2 / W2) of a maximum length L2 of the elongated tread surface in the tire circumferential direction to a maximum width W2 in the tire axial direction is 1.3 to 2.0. [Invention 3] 3. The tire according to claim 1 or 2, wherein an absolute value of a difference between an area A1 of the tread surface of each of the first crown blocks and an area A2 of the tread surface of each of the second crown blocks, |A1-A2|, is 40% or less of the smaller of the area A1 or the area A2. [Invention 4] Each of the plurality of first crown blocks includes a first crown block edge that defines the tread surface; In a plan view of the tread, the first crown block edge includes a recess including a V-shaped edge recessed toward the inside of the tread surface, The tire according to any one of claims 1 to 3, wherein an angle between the V-shaped edges is 80 to 120 degrees. [Invention 5] The tire according to invention 4, wherein two recesses are provided in the first crown block. [Invention 6] The tire according to any one of claims 1 to 5, wherein each of the plurality of crown blocks includes a shallow groove extending linearly. [Invention 7] The tire according to claim 6, wherein two shallow grooves are provided in each of the first crown blocks, and one shallow groove is provided in each of the second crown blocks. [Invention 8] Each of the plurality of first crown blocks includes a first crown block edge that defines the tread surface; In a plan view of the tread, the first crown block edge includes a recess including a V-shaped edge recessed toward the inside of the tread surface, The tire according to claim 6 or 7, wherein the shallow groove of the first crown block is connected to the recessed portion. [The present invention 9] a groove depth of the shallow groove is 30% or less of a block height of each of the second crown blocks; The tire according to any one of claims 6 to 8, wherein the shallow groove has a groove width of 5% to 15% of a maximum width W2 in the tire axial direction of each of the second crown blocks. [The present invention 10] Each of the plurality of first crown blocks includes a first block wall surface extending from the first crown block edge inward in the tire radial direction and outward from the tread surface, The tire according to invention 4, wherein the first block wall surface is inclined at an angle of 10 to 20 degrees with respect to a tread normal to the first crown block edge. [The present invention 11] Each of the plurality of second crown blocks includes a second crown block edge that defines the tread surface, and a second block wall surface that extends from the second crown block edge inward in the tire radial direction and outward from the tread surface, The tire according to any one of claims 1 to 10, wherein the second block wall surface is inclined at an angle of 10 to 20 degrees with respect to a tread normal line perpendicular to the second crown block edge. [The present invention 12] the second crown block edges of the second crown block pair include inner block edges opposed to each other; the inner block edge includes a first inclined portion including a first end of the inner block edge in a longitudinal direction and inclined toward a first side with respect to a tire circumferential direction, and a second inclined portion connected to the first inclined portion and inclined toward a side opposite to the first side, The angle of the first inclined portion with respect to the tire circumferential direction is 20 to 40 degrees, 12. The tire according to claim 11, wherein the second inclined portion has an angle of 40 to 60 degrees with respect to the tire circumferential direction. [The present invention 13] The tread portion includes a tread end, Each of the pair of shoulder block rows includes a plurality of shoulder blocks aligned in the tire circumferential direction, A tire as described in any one of claims 1 to 12, wherein each of the plurality of shoulder blocks includes a first shoulder block that straddles the tread end on both the inside and outside in the tire axial direction, and a second shoulder block that is arranged only on the inside of the tread end in the tire axial direction. [Invention 14] 14. The tire according to claim 13, wherein the maximum axial length of each of the shoulder blocks is 20% to 35% of the tread width. [The present invention 15] Each of the plurality of shoulder blocks includes a shoulder block edge that defines a tread surface; The shoulder block edge includes a pair of lateral block edges extending in the tire axial direction and a longitudinal block edge connecting inner ends of the pair of lateral block edges in the tire axial direction and extending in the tire circumferential direction, 15. The tire according to claim 13 or 14, wherein an angle of the pair of lateral block edges with respect to the tire axial direction is 40 degrees or less. [The present invention 16] 16. The tire according to any one of claims 13 to 15, wherein each of the plurality of shoulder blocks is a plain block not provided with a sipe. [The present invention 17] 17. The tire according to any one of claims 1 to 16, wherein a land ratio of the tread portion is 40% to 60%. [Explanation of symbols]

[0064] 1 Tire 4. Shoulder Block Row 5 Crown Block 7 First Crown Block 7a Tread 8. 2nd Crown Block 8a Tread 9. 2nd Crown Block Pair L1, L2 maximum length W1, W2 maximum width

Claims

1. A tire including a tread portion, The tread portion includes a pair of shoulder block rows and a plurality of crown blocks disposed between the pair of shoulder block rows, The crown block includes a plurality of first crown blocks and a plurality of second crown blocks, the plurality of second crown blocks are arranged such that second crown block pairs, each of which includes two second crown blocks arranged adjacent to each other in the tire axial direction so as to overlap each other in the tire circumferential direction, are repeatedly arranged in the tire circumferential direction, The first crown blocks are disposed between the second crown block pairs adjacent to each other in the tire circumferential direction, Each of the plurality of first crown blocks has a tread surface that is elongated in a circumferential direction and has a maximum length smaller than an axial width of the tire, Each of the second crown blocks has a tread surface that is elongated such that a maximum length in a tire circumferential direction is greater than a maximum width in an axial direction of the tire. tire.

2. a ratio (L1 / W1) of a maximum length L1 in the tire circumferential direction to a maximum width W1 in the tire axial direction of the horizontally elongated tread surface is 0.4 to 0.8; 2. The tire according to claim 1, wherein a ratio (L2 / W2) of a maximum length L2 in the tire circumferential direction of the elongated tread surface to a maximum width W2 in the tire axial direction is 1.3 to 2.

0.

3. 2. The tire according to claim 1, wherein an absolute value |A1-A2| of a difference between the tread area A1 of the first crown block and the tread area A2 of each of the second crown blocks is 40% or less of the smaller of the area A1 or the area A2.

4. each of the plurality of first crown blocks includes a first crown block edge defining the tread surface; In a plan view of the tread, the first crown block edge includes a recess including a V-shaped edge recessed toward the inside of the tread surface, A tire according to any one of claims 1 to 3, wherein the angle between the V-shaped edges is between 80 and 120 degrees.

5. The tire according to claim 4 , wherein two recesses are provided in the first crown block.

6. The tire according to claim 1 , wherein each of the plurality of crown blocks includes a shallow groove extending linearly.

7. The tire according to claim 6 , wherein two shallow grooves are provided in each of the plurality of first crown blocks, and one shallow groove is provided in each of the plurality of second crown blocks.

8. each of the plurality of first crown blocks includes a first crown block edge defining the tread surface; In a plan view of the tread, the first crown block edge includes a recess including a V-shaped edge recessed toward the inside of the tread surface, The tire of claim 7 , wherein the shallow groove of the first crown block leads to the recess.

9. a groove depth of the shallow groove is 30% or less of a block height of each of the second crown blocks; The tire according to claim 6, wherein the shallow groove has a groove width that is 5% to 15% of a maximum width W2 in the tire axial direction of each of the second crown blocks.

10. Each of the plurality of first crown blocks includes a first block wall surface extending from the first crown block edge inward in the tire radial direction and outward from the tread surface, The tire according to claim 4, wherein the first block wall surface is inclined at an angle of 10 to 20 degrees with respect to a tread normal to the first crown block edge.

11. Each of the plurality of second crown blocks includes a second crown block edge that defines the tread surface, and a second block wall surface that extends inward in the tire radial direction from the second crown block edge and outward from the tread surface, 4. The tire according to claim 1, wherein the second block wall surface is inclined at an angle of 10 to 20 degrees with respect to a tread normal to the second crown block edge.

12. the second crown block edges of the second crown block pair include opposing inner block edges; the inner block edge includes a first inclined portion including a first end of the inner block edge in a longitudinal direction and inclined toward a first side with respect to a tire circumferential direction, and a second inclined portion connected to the first inclined portion and inclined toward a side opposite to the first side, The angle of the first inclined portion with respect to the tire circumferential direction is 20 to 40 degrees, The tire according to claim 11, wherein an angle of the second inclined portion with respect to the tire circumferential direction is 40 to 60 degrees.

13. The tread portion includes a tread end, Each of the pair of shoulder block rows includes a plurality of shoulder blocks aligned in the tire circumferential direction, 4. The tire according to claim 1, wherein each of the plurality of shoulder blocks includes a first shoulder block that straddles the tread end on both the inside and outside in the tire axial direction, and a second shoulder block that is arranged only on the inside of the tread end in the tire axial direction.

14. The tire according to claim 13, wherein each of the shoulder blocks has a maximum axial length that is 20% to 35% of the tread width.

15. Each of the plurality of shoulder blocks includes a shoulder block edge that defines a tread surface; The shoulder block edge includes a pair of lateral block edges extending in the tire axial direction and a longitudinal block edge connecting inner ends of the pair of lateral block edges in the tire axial direction and extending in the tire circumferential direction, The tire according to claim 13 , wherein an angle of the pair of lateral block edges with respect to the tire axial direction is equal to or less than 40 degrees.

16. The tire of claim 13 , wherein each of the plurality of shoulder blocks is a plain block that is not provided with sipes.

17. 4. The tire according to claim 1, wherein a land ratio of the tread portion is 40% to 60%.

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