TIRES

Abstract

A tire is provided that ensures excellent block resistance and provides improved driving performance on poor roads. A plurality of shoulder blocks (12) are provided in a shoulder area of ​​a tread section (1). A plurality of side blocks (13) are provided in a side area adjacent to the shoulder area on the outside in a tire width direction. Two or more shoulder blocks (12) adjacent to each other in a tire circumference direction and a side block (13) arranged on the outside in the tire width direction are defined as a block group (B). A curved side groove (20) terminating within the side block (13) is formed on an extension line of a shoulder lug groove (11) arranged between a pair of shoulder blocks (12) enclosed in the block group (B).and the curved side groove (20) includes a connecting section (21) extending from a position of an end section of the shoulder lug groove (11) to an inside in a tire radial direction, and a recurved section (22) curved from an end section of the connecting section (21) on the inside in the tire radial direction to a side in the tire circumferential direction and extending to an outside in the tire radial direction.

Description

Technical field

[0001] The present invention relates to a tire intended for driving on unpaved roads or the like, and relates in particular to a tire that can provide guaranteed excellent block resistance and furthermore improved driving performance on poor roads. State of the art

[0002] Tires (e.g., all-terrain tires or A / T tires) designed for driving on unpaved roads (e.g., uneven terrain, muddy terrain, sandy terrain, and rocky terrain) in addition to paved road surfaces are expected to provide excellent mileage performance on a variety of road surfaces and, in particular, excellent off-road performance (driving performance on poor roads).In such tires, not only is the tread section in contact with the road surface on paved roads, but also a sidewall section (the area between the tread section and a sidewall section) that can come into contact with mud, snow, sand, stones, rocks, and the like (hereinafter collectively referred to as "mud and the like") on the surface of an unpaved road is provided with a textured surface (a sidewall block and the like), which traps mud and the like to maintain good traction (see, for example, patent documents 1 and 2). In recent years, the performance requirements for tires have increased, and further improvements in driving performance on poor roads have become necessary.Since the sidewall tread can be easily damaged by stones, rocks, foreign objects, and the like on unpaved (poor) roads, its durability must also be ensured. Therefore, it is necessary to improve driving performance on poor roads while simultaneously ensuring durability (especially tread resistance) and achieving a very good balance between these two properties. List of literature on patent literature Patent Document 1: JP 2017-124733 A Patent document 2: JP 2020-044882 A Brief description of the invention: Technical problem

[0003] One object of the present invention is to provide a tire that can provide excellent block resistance and also improved driving performance on poor roads. Solution to the problem

[0004] To achieve the above-described objective, a tire according to the present invention is a tire comprising: a tread section extending in the circumferential direction of the tire and having a ring shape; and a pair of sidewall sections arranged on both sides of the tread section.The tire has a surface of the tread section with a pair of main grooves extending along the tire's circumference on both sides of a tire equator; a shoulder area located on the outside of the main grooves in a tire width direction is provided with a plurality of shoulder lug grooves extending from the main grooves to the outside in the tire width direction and spaced at intervals in the tire's circumference direction; and a plurality of shoulder blocks defined by the main grooves and the shoulder lug grooves and arranged along the tire's circumference direction. A sidewall area adjacent to the shoulder area on the outside in the tire width direction is provided with a plurality of side blocks projecting from an outer surface of the sidewall sections.One of the side blocks is positioned, in the tire width direction, on the outside of two or more shoulder blocks that are adjacent to each other in the tire circumference direction. The two or more shoulder blocks and one of the side blocks are combined to form a block group. A curved side groove, terminating within the side block, is formed on an extension line of the shoulder lug groove located between a pair of shoulder blocks enclosed in the block group.The curved side groove includes a connecting section extending from a position of an end section of the shoulder lug groove to an inside in a tire radial direction, and a recurved section curved from an end section of the connecting section on the inside in the tire radial direction to a side in the tire circumferential direction and extending to an outside in the tire radial direction. Advantageous effects of the invention

[0005] In a tire according to the present invention, when a plurality of sidewall blocks are provided in a sidewall area, a sidewall block is arranged at a position on the outer side in a tire width direction of a block group composed of two or more shoulder blocks adjacent to one another in a tire circumferential direction. Therefore, the block group and the sidewall block function entirely as a substantially large block, thereby improving block stability. Furthermore, since a curved sidewall groove including the structure described above is provided in the sidewall block, traction performance can be improved by an edge effect.In particular, because the curved sidewall groove includes a connecting section extending from the end of a shoulder lug groove to an inside in a tire radial direction, and a backbend extending from the end of the connecting section on the inside in the tire radial direction to a side in a tire circumferential direction and extending to an outside in the tire radial direction (that is, extending in a direction opposite to the connecting section), a curved shape exerts the edge effect in various directions, and traction performance can be effectively improved. Since the curved sidewall groove terminates within the sidewall block, it is possible to mitigate any reduction in block stiffness resulting from the groove's placement within the block.Such interaction can provide block stability and driving performance on poor roads in a highly compatible manner.

[0006] In the present invention, a specification is preferably assumed in which a first recessed section, which is recessed from the surface of the side block and projects from the curved side groove, is formed at a position adjacent to the connecting section on an outer side in the tire circumferential direction, and a second recessed section, which is recessed from the surface of the side block and projects from the curved side groove, is formed at a position adjacent to the bent-back section on an outer side in the tire radial direction.By providing the first and second recessed sections in this way, the surface irregularity of the side block can be made more complex while maintaining block stiffness, compared to the case where the number of grooves in the side block is increased, which is advantageous to achieve both block resistance and driving performance on poor roads in a compatible manner.

[0007] In this case, the first and second recessed sections preferably have a recess depth from the surface of the side block in the range of 0.5 mm to 2.5 mm. Furthermore, the area of ​​the second recessed section is preferably 10% to 40% of the area of ​​the first recessed section. By adjusting the recess depth in this way and establishing a size relationship between the recessed sections, the shape of each recessed section and a size balance between the first and second recessed sections are improved, which is advantageous for achieving both block durability and driving performance on poor roads in a compatible manner.

[0008] In the present invention, the groove width of the bent-back section is preferably smaller than the groove width of the connecting section. This makes it easier to ensure block resistance and is advantageous in providing both block resistance and driving performance on poor roads in a compatible manner.

[0009] In the present invention, the curved side groove preferably has a groove depth of 0.5 mm to 3 mm. By adjusting the groove depth and the recess depth of each section in this way, the compensation of the curved side groove and the recessed section is favorably achieved, which is advantageous in order to provide both block resistance and driving performance on poor roads in a compatible manner.

[0010] The present invention can also provide a specification that includes a groove base projection on the bottom of the shoulder stud groove, projecting from the groove base. In the present description, the edge effect can be added by the groove base projection, which is advantageous for improving traction performance.

[0011] The tire of the present invention is preferably a pneumatic tire, but can also be a deflated tire. In the case of a pneumatic tire, its interior can be filled with air, an inert gas such as nitrogen, or another gas. Brief description of the drawings Fig. Figure 1 is a meridian cross-sectional view of a tire according to an embodiment of the present invention. Fig. Figure 2 is a perspective view illustrating a shoulder area and a side area of ​​the tire according to the embodiment of the present invention. Fig. Figure 3 is an explanatory diagram that schematically illustrates a block group (a shoulder block (side surface) and a side block (surface)) of the present invention. Description of embodiments

[0012] Configurations of the present invention are described in detail below with reference to the accompanying drawings.

[0013] If a tire of the present invention is a pneumatic tire, as in Fig. As illustrated in Figure 1, the tire includes a tread section 1 that comes into contact with a road surface, a pair of sidewall sections 2 arranged on both sides of the tread section 1, and a pair of bead sections 3 arranged in a tire radial direction on the inside of each of the pair of sidewall sections 2. The reference numeral “CL” in Fig.1 denotes a tire equator. It should be noted that, although in Fig. Figure 1 does not illustrate which is a meridional cross-sectional view. The tread section 1, the sidewall section 2, and the bead section 3 each extend in a circumferential direction of the tire and form a ring shape, thus creating a toroidal basic structure of the pneumatic tire. Although the description using Fig. 1. Essentially based on an illustrated meridian cross-sectional shape, all tire components extend in the tire circumferential direction and form a ring shape.

[0014] A carcass layer 4 is arranged between a pair of left and right bead sections 3. The carcass layer 4 encloses a plurality of reinforcing cord threads extending in the tire radial direction and is folded back in a tire width direction from an inside to an outside around a bead core 5 arranged in each of the bead sections 3. In addition, a bead filler 6 is arranged on one circumference of the bead core 5, and the bead filler 6 is enclosed by a body section and a folded-back section of the carcass layer 4. On the other hand, in the tread section 1, a plurality of belt layers 7 (two layers in Fig.1) embedded on an outer circumferential side of the carcass layer 4. Each of these belt layers 7 encloses a plurality of reinforcing cord threads inclined with respect to the tire's circumferential direction and arranged such that the reinforcing cord threads intersect each other between the layers. In these belt layers 7, the angle of inclination of the reinforcing cord threads with respect to the tire's circumferential direction is defined in a range of, for example, 10° to 40°. Furthermore, at least one belt reinforcement layer 8 (in Fig. 1 two). The belt reinforcement layer 8 includes organic fiber cord threads oriented in the tire's circumferential direction. In the belt reinforcement layer 8, the angle of the organic fiber cord threads with respect to the tire's circumferential direction is set, for example, to 0° to 5°.

[0015] The present invention relates to a shoulder region and a sidewall region of the tire, as described below, and therefore the basic structure (cross-sectional structure) of the tire is not limited to the general structure described above. Furthermore, the detailed shape (tread pattern) of the grooves and blocks formed on the surface of tread section 1 is not subject to any particular restrictions, with the exception of the shoulder region described below. For the tread pattern of a section, with the exception of the shoulder region described below, it is advantageous to use a pattern that mainly includes blocks suitable for unpaved roads.The present invention can be applied to various tires, including tires without air filling, as long as the tires have areas (sections corresponding to the shoulder area and the side area) that can come into contact with mud and the like on a road surface when driving on unpaved roads.

[0016] As in Fig. 1 and Fig.As illustrated in Figure 2, the surface of the tread section 1 is provided with a pair of main grooves 10, which are configured to extend around the entire circumference of the tire on both sides of the tire equator CL along the tire's circumferential direction. The main groove 10 preferably has a zigzag shape, in which a linear section inclined in one direction with respect to the tire's circumferential direction and a linear section inclined in the other direction are arranged alternately along the tire's circumferential direction. A region between the pair of main grooves 10 is a central region (a region where any tread pattern can be used without specifically limiting the structure in the present invention), and a region on an outer side of each main groove 10 in the tire's width direction is the shoulder region.The main groove 10 has a groove width in a range of preferably 3 mm to 30 mm and more, preferably 5 mm to 11 mm, and a groove depth in a range of preferably 8 mm to 16 mm and more, preferably 10 mm to 15 mm.

[0017] A rib section (shoulder rib section), defined on the outside in the tire width direction of the main groove 10, is provided with a shoulder lug groove 11 extending from the main groove 10 towards the outside in the tire width direction. Preferably, a plurality of shoulder lug grooves 11 are arranged at intervals in the tire circumference direction. The shoulder rib section is subdivided into a plurality of blocks (shoulder blocks 12) by the shoulder lug grooves 11. If the main grooves 10 have a zigzag shape, the shoulder lug grooves 11 preferably connect to each point of curvature on the outside of each main groove 10 in the tire width direction. The groove width of the shoulder lug groove 11 is not particularly limited and is preferably in a range of 70% to 98%, and more preferably in a range of 80% to 95%, of the groove width of the main groove 10.The groove depth of the shoulder stud groove 11 is not particularly limited and is preferably in a range of 75% to 100% and more preferably in a range of 80% to 98% of the groove depth of the main groove 10.

[0018] If an area adjacent to the shoulder region on the outside in the tire width direction is defined as the sidewall area, a plurality of sideblocks 13 are provided in this sidewall area, projecting from an outer surface of the sidewall section 2. The projecting height of each sideblock 13 from the outer surface of the sidewall 2 is not particularly limited and can, for example, be set to 1 mm to 10 mm. As in Fig. 2 and Fig.As illustrated in Figure 3, each side block 13 is arranged in the tire width direction at a position on the outside corresponding to two or more shoulder blocks 12 adjacent to each other in the tire circumference direction. For example, in the illustrated example, one side block 13 is arranged in the tire width direction at the position on the outside of two shoulder blocks 12. In other words, a side groove 14 extending along the tire width direction (tire radial direction) is formed between the side blocks 13 adjacent to each other in the tire circumference direction, and the side groove 14 connects with at least each of the plurality of shoulder lug grooves 11 that are spaced apart in the tire circumference direction.One side block 13 and two or more shoulder blocks 12 (and one or more shoulder stud grooves 11 that do not connect with the side groove 14) are arranged between the shoulder stud grooves 11 and side grooves 14 connected in this way.

[0019] The sidewall block 13 is preferably positioned in a suitable area in the tire's radial direction to ensure adequate contact with the road surface when the tire sinks into mud or similar materials while driving on unpaved roads. In particular, the innermost end of the sidewall block 13 is preferably located within a range of 20% to 50% of the tire's cross-sectional height SH from the position of the tire's equator CL towards the inside of the tire in the radial direction. In other words, a distance D from the position of the tire's equator CL to the innermost end of the sidewall block 13 in the radial direction is preferably 20% to 50% of the tire's cross-sectional height SH. By positioning the sidewall block 13 in a suitable area of ​​the sidewall section 2 in the radial direction, the tire's mileage on unpaved roads can thus be effectively improved.Furthermore, the size of the sidewall block 13 can be appropriately ensured, which is advantageous for ensuring block stiffness and improving durability. If the distance D is less than 20% of the tire's cross-sectional height SH, the sidewall block 13 will be small, making it difficult to maintain satisfactory block stability. If the distance D exceeds 50% of the tire's cross-sectional height SH, the sidewall block 13 will be too large, which can impair normal mileage. It should be noted that, with regard to the arrangement of the sidewall block 13, a boundary between the shoulder area and the sidewall area, regardless of the presence of a ridge 17, is preferably located within a range of 20% to 25% of the tire's cross-sectional height SH from the position of the tire equator CL towards the inside in the tire radial direction.

[0020] It should be noted that in the illustrated example, a burr 15, projecting from the sidewall surface and extending around the entire circumference of the tire, is present at a boundary between the side surface of the shoulder block 12 on the outside in the tire width direction and the upper surface of the side block 13 (the boundary between the shoulder region and the sidewall region). The burr 15 is an element formed due to a gap position of a mold or the like and is therefore not necessarily present. The burr 15 is an element that need not be considered in the present invention and is an element formed during manufacturing; thus, the shoulder region and the sidewall region can be defined with respect to the burr 15.This means that the shoulder area can be considered as an area adjacent to the ridge 15 on the inside in the tire width direction, and the side area can be considered as an area adjacent to the ridge 15 on the inside in the tire radial direction.

[0021] When a combination of two or more shoulder blocks 12 and one side block 13, as described above, is defined as a block group B, the present invention provides a curved side groove 20, terminating within the side block 13, on an extension line of the shoulder lug groove 11 located between the pair of shoulder blocks 12 included in the block group B. The curved side groove 20 has a curved shape that includes a connecting section 21 extending from a position of an end section of the shoulder lug groove 12 to the inside in the tire radial direction, and a recurved section 22 that is curved from an end section of the connecting section 21 on the inside in the tire radial direction to a side in the tire circumferential direction and extends to an outside in the tire radial direction.

[0022] In the tire of the present invention, the entire assembly (block group B), which is composed of the shoulder blocks 12 and the side block 13 described above, essentially functions as one large block, and the stiffness of a block with sufficient volume can be ensured, thereby improving block durability. Furthermore, since the curved side groove 20 with the structure described above is provided within the side block 13, traction performance can be improved by an edge effect.In particular, since the curved side groove 20 includes the connecting section 21, which extends from the position of the end section of the shoulder lug groove 11 to the inside in the tire radial direction, and the recurved section 20, which is curved from the end section of the connecting section 21 on the inside in the tire radial direction to one side in the tire circumferential direction and extends to an outside in the tire radial direction (that is, in a direction opposite to the connecting section 21), its curved shape exerts an edge effect in various directions and traction performance can be effectively improved. Furthermore, since the curved side groove 20 terminates within the side block 13, it is possible to mitigate a reduction in block stiffness due to the addition of the groove.Such interaction can provide both block stability and driving performance on poor roads in a highly compatible manner.

[0023] If the curved side groove 20 does not have the curved shape described above and, for example, extends only linearly from the position of the end section of the shoulder lug groove 11, the groove length cannot be sufficiently ensured and the traction performance cannot be sufficiently improved. If the curved side groove 20 does not end within the block, the side block is divided and the block group B, which is composed of the combination of the multiple shoulder blocks 12 and a side block 13, is not formed, so the block stability cannot be improved.

[0024] The groove depth of the curved side groove 20 is preferably in the range of 0.5 mm to 3 mm, and more preferably in the range of 1 mm to 2 mm. Such a groove depth setting favorably balances the edge effect provided by the curved side groove 20 with the reduction in block stiffness due to the presence of the curved side groove 20. This is advantageous for achieving both block resistance and driving performance on poor roads in a compatible manner. If the groove depth of the curved side groove 20 is less than 0.5 mm, the groove depth is too shallow, and it becomes difficult to adequately ensure the edge effect. If the groove depth of the curved side groove 20 exceeds 3 mm, it becomes difficult to adequately ensure the block stiffness.The connecting section 21 and the bent-back section 22, which form the curved side groove 20, can be adjusted so that they have the same groove depth.

[0025] The curved side groove 20 preferably has a tapered shape, with the groove width gradually decreasing from the position of the end section of the shoulder lug groove 12 to a final end section. At least the groove width of the re-bent section 22 is preferably smaller than the groove width of the connecting section 21. Even when the re-bent section 22 approaches the connecting section 21 due to the curved shape of the curved side groove 20, the groove width of the re-bent section 22 is narrow and block stiffness can be ensured, which is advantageous for achieving both block resistance and driving performance on poor roads in a compatible manner.The maximum groove width of the curved side grooves 20 (groove width at a position where the curved side groove connects with the shoulder lug groove 12) is preferably 25 mm or less and more preferably 5 mm to 20 mm. The tip of the curved side groove 20 (that is, the tip of the recurved section 22) may have an acute-angled shape.

[0026] In the present invention, a first recessed section 31, which is recessed from the surface of the sidewall 13 and projects from the curved side groove 20, is preferably provided at a position adjacent to the connecting section 21 on the opposite side in the circumferential direction of the tire (the side opposite to the direction in which the bent-back section 22 is curved). Furthermore, a second recessed section 32, which is recessed from the surface of the sidewall 13 and projects from the curved side groove 20, is preferably provided at a position adjacent to the bent-back section 22 on the outside in the radial direction of the tire.By providing the first recessed section 31 and the second recessed section 32 separately from the curved side groove 20 in this way, it is possible to make the surface irregularity of the side block 13 complex while maintaining the block stiffness, compared to the case where the number of grooves in the side block 13 is increased, which is advantageous in order to provide both block resistance and driving performance on poor roads in a compatible manner.

[0027] The recess depth of the first recessed section 31 and the second recessed section 32 from the surface of the side block 13 is preferably in the range of 0.5 mm to 2.5 mm, and more preferably from 0.5 mm to 2 mm. By adjusting the recess depth in this way, a satisfactory balance between the curved side groove 20 and each of the recessed sections 31, 32 is achieved, which is advantageous for providing both block stability and driving performance on poor roads in a compatible manner. If the recess depth of the first recessed section 31 and the second recessed section 32 is less than 0.5 mm, the surface of the side block 13 is not sufficiently uneven, and the effect of improving traction performance is limited.If the recess depth of the first recessed section 31 and the second recessed section 32 exceeds 2.5 mm, a depth difference from the curved side groove 20 is essentially eliminated, making it difficult to maintain sufficient block stiffness.

[0028] Each of the first recessed section 31 and the second recessed section 32 is recessed from the surface of the side block 13, as described above, and projects from the curved side groove 20 such that the recess depth of each recessed section is less than the groove depth of the curved side groove 20. At this point, the difference between the recess depth of each recessed section and the groove depth of the curved side groove 20 (that is, the protruding height of each recessed section from the groove bottom of the curved side groove 20) is preferably 0 mm to 3 mm and more preferably 0 mm to 2 mm. This provides a more satisfactory uneven shape formed by each recessed section and the curved side groove 20, which is advantageous for providing both block resistance and driving performance on poor roads in a compatible manner.

[0029] Considering the positional relationship between the first recessed section 31 and the second recessed section 32, the second recessed section 32, adjacent to the re-bent section 22, preferably has a smaller area than the first recessed section 31, adjacent to the connecting section 21 (i.e., on one side closer to the shoulder block 12). In particular, the area of ​​the second recessed section 32 is preferably 10% to 40%, and more preferably 15% to 30%, of the area of ​​the first recessed section 31. This provides a satisfactory balance in size between the first recessed section 31 and the second recessed section 32, which is advantageous for providing both block resistance and driving performance on poor roads in a compatible manner.If the area of ​​the second recessed section 32 is less than 10% of the area of ​​the first recessed section 31, the second recessed section 32 is too small, and therefore the edge effect added by providing the second recessed section 32 cannot be expected to a sufficient degree. If the area of ​​the second recessed section 32 is more than 40% of the area of ​​the first recessed section 31, the proportion of the area of ​​the first recessed section 31 and the second recessed section 32 in the side block 13 increases, and it becomes difficult to maintain sufficient block stiffness.

[0030] The opening area of ​​the curved side groove 20 on the surface of the side block 13 preferably comprises 5% to 40% and more preferably 10% to 30% of the surface of the side block 13 (the total area including the curved side groove 20, the first recessed section 31 and the second recessed section 32). The total area of ​​the first recessed section 31 and the second recessed section 32 preferably comprises 5% to 40% and more preferably 15% to 30% of the surface of the side block 13 (the total area including the curved side groove 20, the first recessed section 31 and the second recessed section 32).

[0031] The groove floor of the shoulder lug groove 11, which is arranged between the pair of shoulder blocks 12 enclosed in block group B, can be provided with a groove floor projection 33 that protrudes from the groove floor. Similarly, another groove floor projection 33 can be provided on the groove floor of another shoulder lug groove 11 (a shoulder lug groove 11 arranged between two block groups B adjacent to each other in the circumferential direction of the tire). By providing the groove floor projections 33 in this way, the edge effect can be further enhanced, which is advantageous in improving traction performance. Furthermore, it is possible to prevent stones from becoming embedded in the shoulder lug grooves 11. The groove floor projection 33 does not protrude from the entire width of the groove floor of the shoulder lug groove 11 and preferably protrudes from a portion of the groove floor of the shoulder lug groove 11, as illustrated.The width of the groove bottom projection 33 is preferably in a range of 10% to 40% and more, preferably 15% to 25%, of the groove width of the shoulder lug groove 11. A projecting height of the groove bottom projection 33 is preferably in a range of 0.5 mm to 3 mm and more, preferably 1 mm to 2 mm.

[0032] The present invention is further described below with reference to examples, but the scope of the present invention is not limited to these examples. Example

[0033] Fifteen types of pneumatic tires were manufactured, including prior art example 1, comparative examples 1 and 2, and examples 1 to 12. The tires had a tire size of LT265 / 70R17 121 / 118S and a tread depth of 12 mm. Fig. 1 illustrated basic structure (cross-sectional structure) and showed a shoulder area and a side area with structures based on Fig.2 and the number of shoulder blocks adjacent to a side block on an outer side in a tire radial direction, the presence of a curved side groove, the groove depth of the curved side groove, the maximum width of the curved side groove, the presence of a first recessed section adjacent to a connecting section of the curved side groove, the presence of a second recessed section adjacent to a recurved section of the curved side groove, the recess depth of the first / second recessed section, the ratio of the area of ​​the second recessed section to the area of ​​the first recessed section and the presence of a groove bottom projection of a shoulder lug groove were set as shown in Tables 1 and 2.

[0034] It should be noted that the tread pattern of a central area is the same in all examples and that the tread pattern has a structure in which a row of blocks is arranged between a pair of main grooves and on each side of a tire equator.

[0035] In the column "Presence of a curved sidewall groove" in Tables 1 and 2, the case where the curved sidewall groove was not present and a groove was present extending from the position of the end section of the shoulder lug groove to an inner side in the tire's radial direction and ending within the sidewall block (Comparison Example 2) was described as a "linear sidewall groove". For simplicity, in this case, the values ​​for the groove depth and maximum width of the linear sidewall groove are described in the columns "Groove depth of the curved sidewall groove" and "Maximum width of the curved sidewall groove".

[0036] The pneumatic tires were evaluated for their driving performance on poor roads and block resistance using the evaluation procedures described below, the results of which are given together in Tables 1 and 2. Driving performance on bad roads

[0037] Each test tire was mounted on a wheel with a rim size of 17 × 8 J and fitted to a test vehicle (traction test vehicle) with a front tire pressure of 450 kPa and a rear tire pressure of 550 kPa. A test driver then performed a sensory evaluation of the traction characteristics (starting behavior) on a test track consisting of an unpaved road (gravel surface). Evaluation results are expressed as index values, with Example 1 of the prior art assigned an index value of 100. Higher index values ​​indicate that the tire exhibits excellent road performance. Block resistance (cut resistance)

[0038] Each test tire was mounted on a wheel with a rim size of 17 × 8J, inflated to a pressure of 350 kPa, and fitted to a test vehicle (all-wheel-drive SUV). The total length of a cut produced in a side section was then measured after driving 1000 km on an off-road endurance course. The evaluation results were expressed as index values, with the inverse of the measurement from State of the Art Example 1 being assigned an index value of 100. A higher index value indicates a shorter total cut length and excellent block resistance (cut resistance). [Table 1-I] State of the art example 1 Comparative example 1 Comparative example 2 Number of shoulder blocks adjacent to the side blocks 1 2 2 Presence of the curved side groove Unavailable Unavailable Linear side groove Groove depth of the curved side groove (mm) - - 2 Maximum width of the curved side groove (mm) - - 19 Presence of the first recessed section Unavailable Unavailable Unavailable Presence of the second recessed section Unavailable Unavailable Unavailable Recess depth of the first / second recessed section (mm) Ratio of the area of ​​the second recessed section to the area of ​​the first recessed section [%] - - - Presence of the groove floor projection Unavailable Unavailable Unavailable Driving performance on poor roads (index value) 100 102 103 Block resistance (index value) 100 110 108 [Table 1-II] Example 1 Example 2 Example 3 Example 4 Number of shoulder blocks adjacent to the side blocks 2 2 2 2 Presence of the curved side groove Available Available Available Available Groove depth of the curved side groove (mm) 2 2 2 2 Maximum width of the curved side groove (mm) 19 19 19 19 Presence of the first recessed section Unavailable Available Unavailable Available Presence of the second recessed section Unavailable Available Available Unavailable Recess depth of the first / second recessed section (mm) - 1 1 1 Ratio of the area of ​​the second recessed section to the area of ​​the first recessed section [%] - 22 - - Presence of the groove floor projection Unavailable Unavailable Unavailable Unavailable Driving performance on poor roads (index value) 106 110 107 107 Block resistance (index value) 108 106 107 107 [Table 2-I] Example 5 Example 6 Example 7 Example 8 Number of shoulder blocks adjacent to the side blocks 2 2 2 2 Presence of the curved side groove Available Available Available Available Groove depth of the curved side groove (mm) 0,5 3 2 2 Maximum width of the curved side groove (mm) 19 19 25 19 Presence of the first recessed section Available Available Available Available Presence of the second recessed section Available Available Available Available Recess depth of the first / second recessed section (mm) 1 1 1 0,5 ratio of the area of ​​the second recessed area 22 22 22 22 Section for the area of ​​the first recessed section [%] Presence of a grooved floor projection Unavailable Unavailable Unavailable Unavailable Driving performance on poor roads (index value) 108 110 110 108 Block resistance (index value) 107 105 105 107 [Table 2-II] Example 9 Example 10 Example 11 Example 12 Number of shoulder blocks adjacent to the side blocks 2 2 2 2 Presence of the curved side groove Available Available Available Available Groove depth of the curved side groove (mm) 2 2 2 2 Maximum width of the curved side groove (mm) 19 19 19 19 Presence of the first recessed section Available Available Available Available Presence of the second recessed section Available Available Available Available Recess depth of the first / second recessed section (mm) 2,5 1 1 1 Ratio of the area of ​​the second recessed section to the area of ​​the first recessed section [%] 22 10 40 22 Presence of a grooved floor projection Unavailable Unavailable Unavailable Available Driving performance on poor roads (index value) 110 109 110 111 Block resistance (index value) 105 107 105 106

[0039] As can be seen from Tables 1 and 2, the pneumatic tires of Examples 1 to 12 provide improved road performance on poor roads and block resistance in a balanced and compatible manner compared to those of Example 1 of the prior art. On the other hand, since the structure of Comparative Example 1 is such that two shoulder blocks are arranged adjacent to a side block, block resistance was improved compared to Example 1 of the prior art, but the effect of improving road performance on poor roads was not sufficiently achieved because the curved side groove was not provided. In Comparative Example 2, because linear side grooves were provided instead of curved side grooves, road performance on poor roads could not be improved sufficiently. List of reference symbols 1 tread section 2 Side wall section 3 bead section 4 Carcass layer 5 bead core 6 bead fillers 7th belt layer 8 Belt reinforcement layer 10 Main groove 11 Shoulder stud groove 12 Shoulder block 13 page block 14 side groove 15 degrees 20 Curved side groove 21 Connecting section 22 Recurved section 31 First omitted section 32 Second recessed section 33 Grooved floor projection CL tire equator B Block Group QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2017-124733 A

[0002] JP 2020-044882 A

[0002]

Claims

A tire comprising: a tread section extending in a circumferential direction and having a ring shape; and a pair of sidewall sections arranged on both sides of the tread section; a surface of the tread section provided with a pair of main grooves extending along the circumferential direction on both sides of a tire equator; a shoulder area located on the outside of the main grooves in a width direction and provided with a plurality of shoulder lug grooves extending from the main grooves to the outside in the width direction and spaced at intervals in the circumferential direction, and a plurality of shoulder blocks defined by the main grooves and the shoulder lug grooves and arranged along the circumferential direction; a sidewall area;which adjoins the shoulder area on the outside in the tire width direction and is provided with a plurality of side blocks projecting from an outer surface of the sidewall sections, wherein one of the side blocks is arranged in the tire width direction at a position on the outside of two or more of the shoulder blocks that adjoin each other in the tire circumferential direction, wherein the two or more shoulder blocks and one of the side blocks are combined to form a block group, a curved side groove terminating within the side block and formed on an extension line of the shoulder lug groove located between a pair of shoulder blocks contained in the block group, and wherein the curved side groove comprises a connecting section extending from a position of an end section of the shoulder lug groove to an inside in a tire radial direction, and a recurved section,which is curved from an end section of the connecting section on the inside in the tire radial direction to one side in the tire circumferential direction and extends to an outside in the tire radial direction. Tire according to claim 1, wherein a first recessed section, which is recessed from a surface of the side block and projects from the curved side groove, is formed at a position adjacent to the connecting section on the other side in the circumferential direction of the tire, and a second recessed section, which is recessed from the surface of the side block and projects from the curved side groove, is formed at a position adjacent to the bent-back section on the outside in the radial direction of the tire. Tires according to claim 2, wherein the first recessed section and the second recessed section have a recess depth from the surface of the sidewall block in a range of 0.5 mm to 2.5 mm. Tires according to claim 2 or 3, wherein an area of ​​the second recessed section is 10% to 40% of an area of ​​the first recessed section. Tires according to one of claims 1 to 4, wherein a groove depth of the re-bent section is less than a groove depth of the connecting section. Tires according to any one of claims 1 to 5, wherein the curved side groove has a groove depth of 0.5 mm to 3 mm. Tires according to one of claims 1 to 6, further comprising a groove bottom projection on a groove bottom of the shoulder lug groove, which projects from the groove bottom.

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