Tire

Abstract

The present invention provides a tire capable of further improving trafficability on bad road conditions while ensuring excellent durability of pattern blocks. A plurality of shoulder blocks (12) are provided in a shoulder region of a tread portion (1), a plurality of sidewall blocks (13) are provided in a sidewall region adjacent to the outer side of the shoulder region in the tire width direction, and two or more shoulder blocks (12) adjacent to each other in the tire circumferential direction and one sidewall block (13) disposed on the outer side in the tire width direction are set as block groups (B). A curved sidewall groove (20) terminating within a sidewall block (13) is formed on an extension line of a shoulder lug groove (11) disposed between a pair of shoulder blocks (12) included in a block group (B), the curved sidewall groove (20) including: a connecting portion (21) extending inward in a tire radial direction from an end position of the shoulder lug groove (11); and a folded-back section (22) that is bent toward one side in the tire circumferential direction from the end section of the connection section (21) on the inner side in the tire radial direction and extends toward the outer side in the tire radial direction.

Description

Technical Field

[0001] This invention relates to a tire for driving on unpaved roads, etc., and more specifically, to a tire that can further improve performance in harsh road conditions while ensuring excellent tread block durability. Background Technology

[0002] For tires designed to operate not only on paved roads but also on unpaved roads (uneven surfaces, mud, sand, rocky areas, etc.) (e.g., all-terrain tires), excellent performance on various road surfaces is required, especially superior off-road performance (performance in traversing harsh conditions). In such tires, the industry practice is to not only create tread blocks (sidewall tread blocks, etc.) on the tread section where it contacts the road surface on paved roads, but also on the sidewall area (the area between the tread section and the sidewall) where it might come into contact with mud, snow, sand, stones, rocks, etc. (hereinafter collectively referred to as "mud, etc.") on unpaved roads. This allows the mud, etc., to be trapped, thereby improving traction (see, for example, Patent Documents 1 and 2). In recent years, the industry has raised performance requirements for tires, demanding further improvements in performance in traversing harsh conditions. Furthermore, the sidewall tread blocks are prone to damage on unpaved roads (bad road conditions) due to stones, rocks, and other debris on the road surface, thus requiring guaranteed durability. Therefore, it is necessary to improve the performance on bad roads while ensuring durability (especially tread block durability), and to take these performance characteristics into account.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-124733

[0006] Patent Document 2: Japanese Patent Application Publication No. 2020-044882 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this invention is to provide a tire that can further improve its performance in harsh road conditions while ensuring excellent tread block durability.

[0009] Methods for solving problems

[0010] The tire of the present invention, for achieving the above-mentioned objectives, comprises an annular tread portion extending circumferentially along the tire and a pair of sidewall portions disposed on both sides of the tread portion. The tread portion surface has a pair of main grooves extending circumferentially on both sides of the tire equator; a shoulder region located outside the main grooves in the tire width direction has: a plurality of shoulder lateral grooves extending outward from the main grooves in the tire width direction and spaced apart circumferentially; and a plurality of shoulder tread blocks divided by the main grooves and the shoulder lateral grooves and arranged circumferentially; and a sidewall region adjacent to the shoulder region in the tire width direction has a protrusion extending from the outer surface of the sidewall portions. A plurality of sidewall tread blocks are provided, with one sidewall tread block positioned on the outer side of two or more adjacent shoulder tread blocks in the tire width direction. When the combination of two or more shoulder tread blocks and one sidewall tread block is configured as a tread block group, a curved sidewall groove terminating within the sidewall tread block is formed on the extension line of the shoulder lateral groove between a pair of shoulder tread blocks included in the tread block group. The curved sidewall groove includes: a connecting portion extending radially inward from the end position of the shoulder lateral groove towards the tire; and a folded-back portion bending from the radially inward end of the connecting portion towards one side in the tire circumferential direction and extending radially outward from the tire.

[0011] Invention Effects

[0012] When the tire of the present invention has multiple sidewall tread blocks in the sidewall area, a sidewall tread block is positioned on the outer side of the tire width direction of a tread block group consisting of two or more adjacent shoulder tread blocks in the tire circumferential direction. Therefore, the entire tread block group and the sidewall tread block function as a single large tread block, thereby improving tread block durability. On the other hand, since the curved sidewall groove with the above-described structure is provided within the sidewall tread block, traction performance can be improved through its edge effect. In particular, the curved sidewall groove includes: a connecting portion that extends radially inward from the end of the shoulder lateral groove; and a folded-back portion that bends from the radially inward end of the connecting portion towards one side in the tire circumferential direction and extends radially outward from the tire (i.e., in the opposite direction to the connecting portion). Therefore, its curved shape can exert an edge effect in each direction, thereby effectively improving traction performance. It should be noted that since the curved sidewall groove terminates within the sidewall tread block, the reduction in tread block rigidity caused by the groove within the tread block can be suppressed. Through the collaboration of these settings, a high degree of balance can be achieved between the durability of the tread blocks and their performance in harsh road conditions.

[0013] In this invention, the following specifications are preferably provided: a first recess is formed at a position adjacent to the tire circumferential side of the connecting portion, recessed from the surface of the sidewall tread block and higher than the curved sidewall groove; a second recess is formed at a position adjacent to the radially outer side of the folded-back portion, recessed from the surface of the sidewall tread block and higher than the curved sidewall groove. By providing the first and second recesses in this way, compared to adding grooves within the sidewall tread block, the surface irregularities of the sidewall tread block can be made more complex while maintaining the rigidity of the tread block, which is beneficial for balancing tread block durability and performance in harsh road conditions.

[0014] At this point, the indentation amount of the first and second recesses relative to the surface of the sidewall tread block is preferably 0.5 mm to 2.5 mm. Furthermore, the area of ​​the second recess is preferably 10% to 40% of the area of ​​the first recess. By setting the indentation amount and size relationship of the recesses in this way, a good balance is achieved between the shape of each recess and the size of the first and second recesses, which is beneficial for balancing tread block durability and performance in harsh road conditions.

[0015] In this invention, the groove width of the folded-back portion is preferably smaller than the groove width of the connecting portion. This makes it easier to ensure the rigidity of the tread block, thereby balancing the durability of the tread block with its performance in harsh road conditions.

[0016] In this invention, the groove depth of the curved sidewall groove is preferably 0.5mm to 3mm. By setting the groove depth and recess amount of each part in this way, a good balance is achieved between the curved sidewall groove and the recess, which is beneficial to both the durability of the tread blocks and the performance in harsh road conditions.

[0017] In this invention, the shoulder lateral grooves may also have a raised bottom protrusion. This feature increases the edge effect caused by the raised bottom, thus improving traction performance.

[0018] The tire of the present invention is preferably a pneumatic tire, but it can also be a non-pneumatic tire. When it is a pneumatic tire, its interior can be filled with air, nitrogen, or other inert gases. Attached Figure Description

[0019] Figure 1 This is a radial cross-sectional view of a tire constructed according to an embodiment of the present invention.

[0020] Figure 2 This is a perspective view showing the shoulder region and sidewall region of a tire constructed according to an embodiment of the present invention.

[0021] Figure 3 This is an explanatory diagram schematically showing the pattern block assembly (shoulder pattern block (side) and sidewall pattern block (surface)) of the present invention. Detailed Implementation

[0022] Hereinafter, the structure of the present invention will be described in detail with reference to the accompanying drawings.

[0023] Regarding the tire of the present invention, it is as follows: Figure 1 The pneumatic tire shown includes a tread portion 1 that contacts the road surface, a pair of sidewall portions 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3 disposed radially inside the sidewall portions 2. Figure 1 In the attached diagram, the symbol CL indicates the tire equator. It should be noted that, due to... Figure 1 This is a radial cross-sectional view, so although it is not depicted, the tread portion 1, sidewall portion 2, and bead portion 3 extend circumferentially along the tire to form a ring, thus constituting the basic annular structure of a pneumatic tire. The following will use... Figure 1 The description is based primarily on the meridian profile shown in the illustration, with each tire component extending circumferentially to form a ring.

[0024] A carcass layer 4 is provided between a pair of left and right bead portions 3. The carcass layer 4 includes multiple reinforcing cords extending radially along the tire and folded back from the inside to the outside in the tire width direction around the bead core 5 disposed in each bead portion 3. Furthermore, a sidewall core 6 is disposed on the outer periphery of the bead core 5, and this sidewall core 6 is covered by the main body and folded-back portion of the carcass layer 4. On the other hand, multiple layers (in...) are embedded on the outer periphery of the carcass layer 4 in the tread portion 1. Figure 1 The belt layer 7 consists of two layers. Each belt layer 7 includes multiple reinforcing cords inclined relative to the tire circumference, and the reinforcing cords are arranged in a crisscrossing manner between the layers. In these belt layers 7, the inclination angle of the reinforcing cords relative to the tire circumference is, for example, set in the range of 10° to 40°. Furthermore, at least one layer is provided on the outer periphery of the belt layer 7. Figure 1 The belt reinforcement layer 8 consists of two layers. The belt reinforcement layer 8 includes organic fiber cords oriented in the tire circumferential direction. In the belt reinforcement layer 8, the angle of the organic fiber cords relative to the tire circumferential direction is, for example, set to 0° to 5°.

[0025] As described later, this invention relates to the shoulder and sidewall regions of a tire; therefore, the basic structure (sectional structure) of the tire is not limited to the conventional structure described above. Furthermore, the specific shapes of the grooves and tread blocks formed on the surface of the tread portion 1 (tread pattern) are not particularly limited except for the shoulder region described later. The tread pattern in the portion other than the shoulder region described later is suitable for using tread blocks primarily adapted for unpaved roads. This invention can be applied to various tires, including non-pneumatic tires, as long as they have areas (corresponding to the shoulder and sidewall regions) that may come into contact with mud or other substances on the road surface when driving on unpaved roads.

[0026] like Figure 1 , 2As shown, on the surface of the tread 1, a pair of main grooves 10 are formed on both sides of the tire equator CL, extending circumferentially and throughout the entire circumference of the tire. Preferably, the main grooves 10 have a serrated shape formed by alternating straight sections inclined in one direction and straight sections inclined in another direction relative to the tire circumferential direction. The area between the pair of main grooves 10 is the central area (in this invention, the area with no particular structural limitation and which can adopt any tread pattern), and the area on the outer side of each main groove 10 in the tire width direction is the shoulder area. The groove width of the main groove 10 is preferably 3mm to 30mm, more preferably 5mm to 11mm, and the groove depth is preferably 8mm to 16mm, more preferably 10mm to 15mm.

[0027] A shoulder lateral groove 11 extending outward from the main groove 10 in the tire width direction is provided on the circumferential portion (shoulder circumferential portion) defined on the outer side of the main groove 10. It is preferable that multiple shoulder lateral grooves 11 are provided at intervals in the tire circumferential direction. Through these shoulder lateral grooves 11, the shoulder circumferential portion is divided into multiple tread blocks (shoulder tread blocks 12). When the main groove 10 has a serrated shape, it is preferable that the shoulder lateral grooves 11 connect to the bending points on the outer side of each main groove 10 in the tire width direction. The width of the shoulder lateral groove 11 is not particularly limited, but is preferably 70% to 98% of the width of the main groove 10, more preferably 80% to 95%. The depth of the shoulder lateral groove 11 is not particularly limited, but is preferably 75% to 100% of the depth of the main groove 10, more preferably 80% to 98%.

[0028] When the area adjacent to the outer side of the tire shoulder area in the tire width direction is defined as the sidewall area, a plurality of sidewall tread blocks 13 are provided in this sidewall area, protruding from the outer surface of the sidewall portion 2. The height of each sidewall tread block 13 protruding from the outer surface of the sidewall 2 is not particularly limited, and can be set to, for example, 1mm to 10mm. Figure 2 , 3 As shown, each sidewall tread block 13 is positioned on the outer side of the tire width direction at the position corresponding to two or more adjacent shoulder tread blocks 12 in the tire circumferential direction. For example, in the example shown, a sidewall tread block 13 is positioned on the outer side of the tire width direction between two shoulder tread blocks 12. In other words, a sidewall groove 14 extending in the tire width direction (tire radial direction) is formed between adjacent sidewall tread blocks 13 in the tire circumferential direction. This sidewall groove 14 is connected to at least every other one of a plurality of shoulder lateral grooves 11 arranged at intervals in the tire circumferential direction. Between such connected shoulder lateral grooves 11 and sidewall grooves 14, one sidewall tread block 13 and two or more shoulder tread blocks 12 (and one or more shoulder lateral grooves 11 not connected to the sidewall groove 14) are arranged.

[0029] The sidewall tread blocks 13 are preferably positioned within a suitable range in the tire's radial direction to ensure proper contact with the road surface when the tire gets stuck in mud or other debris while driving on unpaved roads. Specifically, it is preferable that the innermost radial end of the sidewall tread blocks 13 is within a range of 20% to 50% of the tire section height SH from the tire equator CL towards the innermost radial direction. In other words, the distance D from the tire equator CL to the innermost radial end of the sidewall tread blocks 13 is preferably 20% to 50% of the tire section height SH. By positioning the sidewall tread blocks 13 within a suitable range in the tire's radial direction of the sidewall portion 2, driving performance on unpaved roads can be effectively improved. Furthermore, since the size of the sidewall tread blocks 13 can be appropriately ensured, it is beneficial to ensure tread block rigidity and improve durability. If the distance D is less than 20% of the tire section height SH, the sidewall tread blocks 13 become too small, making it difficult to maintain good tread block durability. If the distance D exceeds 50% of the tire section height SH, the sidewall tread blocks 13 become too large, which may affect normal driving performance. It should be noted that, regarding the configuration of the sidewall tread blocks 13, regardless of the presence or absence of the spurs 17, the boundary between the tire shoulder area and the tire sidewall area should preferably be within 20% to 25% of the tire section height SH from the tire equator CL towards the radial inward side of the tire.

[0030] It should be noted that in the example shown, at the boundary between the outer side of the shoulder tread block 12 in the tire width direction and the surface of the sidewall tread block 13 (the boundary between the shoulder region and the sidewall region), there is a protrusion 15 that rises from the sidewall surface and extends throughout the entire circumference of the tire. This protrusion 15 is an element formed due to the mold's cutting position, etc., and therefore is not necessary. This protrusion 15 is an element that does not need to be considered in this invention, but since it is an element formed in manufacturing, the shoulder region and the sidewall region can also be divided based on the protrusion 15. That is, the shoulder region can be considered as the region adjacent to the inner side of the protrusion 15 in the tire width direction, and the sidewall region is the region adjacent to the inner side of the protrusion 15 in the tire radial direction.

[0031] When the combination of two or more shoulder tread blocks 12 and one sidewall tread block 13 is designated as tread block group B, in this invention, a curved sidewall groove 20 terminating within the sidewall tread block 13 is formed on the extension line of the shoulder lateral groove 11 disposed between a pair of shoulder tread blocks 12 included in tread block group B. This curved sidewall groove 20 has a curved shape including a connecting portion 21 and a fold-back portion 22. The connecting portion 21 extends radially inward from the end position of the shoulder lateral groove 12 towards the tire's radial interior, and the fold-back portion 22 bends from the radially inward end of the connecting portion 21 towards one side of the tire's circumferential direction and extends radially outward from the tire's radial exterior.

[0032] In the tire of the present invention, the entire assembly (pattern block group B) consisting of the aforementioned shoulder tread block 12 and sidewall tread block 13 functions essentially as a large tread block, ensuring rigidity as a tread block with sufficient volume, thereby improving tread block durability. On the other hand, since the curved sidewall groove 20 of the aforementioned structure is provided within the sidewall tread block 13, traction performance can be improved through its edge effect. In particular, the curved sidewall groove 20 includes: a connecting portion 21 extending radially inward from the end position of the shoulder lateral groove 11; and a fold-back portion 20 bending towards one side of the tire circumferential direction from the end of the connecting portion 21 radially inward and extending radially outward (i.e., extending in the opposite direction to the connecting portion 21). Therefore, its curved shape allows for edge effects in various directions, effectively improving traction performance. Furthermore, since the curved sidewall groove 20 terminates within the sidewall tread block 13, the reduction in tread block rigidity caused by the additional groove can be suppressed. Through the collaboration of these settings, a high degree of balance can be achieved between the durability of the tread blocks and their performance in harsh road conditions.

[0033] If the curved sidewall groove 20 does not have the aforementioned curved shape, for example, if it extends linearly only from the end of the shoulder lateral groove 11, the groove length cannot be sufficiently ensured, thus failing to adequately improve traction performance. If the curved sidewall groove 20 does not terminate within the tread block, the sidewall tread block will be truncated, and the tread block group B, consisting of multiple shoulder tread blocks 12 and one sidewall tread block 13, cannot be formed, thus failing to improve tread block durability.

[0034] The groove depth of the curved sidewall groove 20 is preferably 0.5mm to 3mm, more preferably 1mm to 2mm. By setting this groove depth, a good balance is achieved between the edge effect introduced by the curved sidewall groove 20 and the reduction in tread block rigidity caused by its installation, which is beneficial for balancing tread block durability and performance in harsh road conditions. If the groove depth of the curved sidewall groove 20 is less than 0.5mm, the groove depth is too small, making it difficult to adequately ensure the edge effect. If the groove depth of the curved sidewall groove 20 exceeds 3mm, it is difficult to adequately ensure the tread block rigidity. It should be noted that the connecting portion 21 and the folded-back portion 22 constituting the curved sidewall groove 20 are preferably set to the same groove depth.

[0035] The curved sidewall groove 20 preferably has a pointed shape in which the groove width gradually narrows from the end of the shoulder lateral groove 12 toward the terminal end. Preferably, the groove width of at least the fold-back portion 22 is smaller than the groove width of the connecting portion 21. Even if the fold-back portion 22 is close to the connecting portion 21 due to the curved shape of the curved sidewall groove 20, the narrowing of the groove width of the fold-back portion 22 ensures the rigidity of the tread block, which is beneficial for balancing tread block durability and performance in harsh road conditions. The maximum groove width of the curved sidewall groove 20 (the groove width at the position where it connects with the shoulder lateral groove 12) is preferably 25 mm or less, more preferably 5 mm to 20 mm. Furthermore, the front end of the curved sidewall groove 20 (i.e., the front end of the fold-back portion 22) is preferably an acute angle.

[0036] In this invention, it is preferable to provide a first recess 31 that is recessed from the surface of the sidewall tread block 13 and higher than the curved sidewall groove 20, located adjacent to the tire circumferential side of the connecting portion 21 (the side opposite to the bending direction of the fold-back portion 22). Furthermore, it is preferable to provide a second recess 32 that is recessed from the surface of the sidewall tread block 13 and higher than the curved sidewall groove 20, located adjacent to the tire radially outer side of the fold-back portion 22. By providing the first recess 31 and the second recess 32 separately from the curved sidewall groove 20, compared to adding grooves within the sidewall tread block 13, the surface of the sidewall tread block 13 can be made more complex while maintaining the rigidity of the tread block, which is beneficial for balancing tread block durability and performance in harsh road conditions.

[0037] The recess amount of the first recess 31 and the second recess 32 relative to the surface of the sidewall tread block 13 is preferably 0.5mm to 2.5mm, more preferably 0.5mm to 2mm. By setting the recess amount in this way, a good balance is achieved between the curved sidewall groove 20 and each recess 31, 32, which is beneficial for balancing the durability of the tread block and its performance in harsh road conditions. If the recess amount of the first recess 31 and the second recess 32 is less than 0.5mm, the surface of the sidewall tread block 13 is not sufficiently textured, and the effect of improving traction performance is limited. If the recess amount of the first recess 31 and the second recess 32 exceeds 2.5mm, there is no substantial difference from the depth of the curved sidewall groove 20, and therefore it is difficult to maintain the rigidity of the tread block sufficiently.

[0038] The first recess 31 and the second recess 32 are recessed from the surface of the sidewall tread block 13 as described above and are higher than the curved sidewall groove 20. Therefore, the amount of recess in each recess is less than the groove depth of the curved sidewall groove 20. At this time, the difference between the amount of recess in each recess and the groove depth of the curved sidewall groove 20 (i.e., the height of the protrusion of each recess from the bottom of the curved sidewall groove 20) is preferably 0 mm to 3 mm, and more preferably 0 mm to 2 mm. As a result, the concave-convex shape formed by each recess and the curved sidewall groove 20 becomes good, which is beneficial for balancing the durability of the tread block and the performance in harsh road conditions.

[0039] When considering the positional relationship between the first recess 31 and the second recess 32, it is preferable that the area of ​​the second recess 32 adjacent to the folded-back portion 22 is smaller than the area of ​​the first recess 31 adjacent to the connecting portion 21 (i.e., the side near the shoulder tread block 12). Specifically, the area of ​​the second recess 32 is preferably 10% to 40% of the area of ​​the first recess 31, more preferably 15% to 30%. This achieves a good balance between the sizes of the first recess 31 and the second recess 32, which is beneficial for balancing tread block durability and performance under harsh road conditions. If the area of ​​the second recess 32 is less than 10% of the area of ​​the first recess 31, the second recess 32 is too small, and therefore the increased edge effect due to the second recess 32 cannot be adequately anticipated. If the area of ​​the second recess 32 exceeds 40% of the area of ​​the first recess 31, the proportion of the first recess 31 and the second recess 32 in the sidewall tread block 13 becomes larger, making it difficult to adequately maintain tread block rigidity.

[0040] The opening area of ​​the curved sidewall groove 20 on the surface of the sidewall tread block 13 is preferably 5% to 40% of the total surface area of ​​the sidewall tread block 13 (including the curved sidewall groove 20, the first recess 31, and the second recess 32), and more preferably 10% to 30%. Furthermore, the combined area of ​​the first recess 31 and the second recess 32 is preferably 5% to 40% of the total surface area of ​​the sidewall tread block 13 (including the curved sidewall groove 20, the first recess 31, and the second recess 32), and more preferably 15% to 30%.

[0041] At the bottom of the shoulder lateral tread groove 11 located between a pair of shoulder tread blocks 12 included in tread block group B, a groove bottom protrusion 33 can be provided. Similarly, groove bottom protrusions 33 can also be provided at the bottom of other shoulder lateral tread grooves 11 (shoulder lateral tread grooves 11 located between two adjacent tread block groups B in the tire circumferential direction). By providing groove bottom protrusions 33 in this way, the edge effect can be further increased, thus improving traction performance. In addition, it can also prevent stones from embedding in the shoulder lateral tread groove 11. The groove bottom protrusion 33 is not a groove bottom protrusion along the entire width of the shoulder lateral tread groove 11, but rather, as shown in the figure, a portion of the groove bottom of the shoulder lateral tread groove 11 is protruded. The width of the groove bottom protrusion 33 is preferably 10% to 40% of the groove width of the shoulder lateral tread groove 11, more preferably 15% to 25%. The height of the protrusion 33 at the bottom of the groove is preferably 0.5mm to 3mm, and more preferably 1mm to 2mm.

[0042] The present invention will be further described below through embodiments, but the scope of the present invention is not limited to these embodiments.

[0043] Example

[0044] Fifteen types of pneumatic tires were manufactured, including Conventional Example 1, Comparative Examples 1-2, and Examples 1-12, with tire dimensions of LT265 / 70R17 121 / 118S, and possessing... Figure 1 The illustrated basic structure (cross-sectional structure), the structure of the shoulder area and the sidewall area are as follows: Figure 2 Based on the above, the following parameters are set as shown in Tables 1-2: number of shoulder tread blocks adjacent to the radial outer side of a tire sidewall tread block, presence or absence of curved sidewall grooves, groove depth of curved sidewall grooves, maximum width of curved sidewall grooves, presence or absence of a first recess adjacent to the connection portion of the curved sidewall groove, presence or absence of a second recess adjacent to the folded-back portion of the curved sidewall groove, amount of depression of the first / second recess, ratio of the area of ​​the second recess to the area of ​​the first recess, and presence or absence of a groove bottom protrusion of the shoulder lateral groove.

[0045] It should be noted that the tread pattern in the central area is the same in all examples, forming a structure with one row of tread blocks arranged between a pair of main grooves and on each side of the tire equator.

[0046] Regarding the "Presence or Absence of Curved Sidewall Grooves" column in Tables 1 and 2, for cases where curved sidewall grooves are not formed, but grooves are formed that extend radially inward from the end of the shoulder lateral grooves and terminate within the sidewall tread blocks (Comparative Example 2), it is recorded as "Straight Sidewall Groove". For convenience, the values ​​of the groove depth and maximum width of the straight sidewall groove are recorded in the "Groove Depth of Curved Sidewall Groove" and "Maximum Width of Curved Sidewall Groove" columns for this case.

[0047] The following evaluation methods were used to assess the performance of these pneumatic tires in adverse road conditions and the durability of their tread blocks, and the results are shown in Tables 1 and 2.

[0048] Performance in adverse road conditions

[0049] Each test tire was assembled onto a 17×8J rimmed wheel. The front tire pressure was set to 450 kPa, and the rear tire pressure to 550 kPa. The tires were then mounted on the test vehicle (traction test vehicle). Test drivers conducted a sensory evaluation of traction (starting performance) on a test surface consisting of unpaved road (gravel road). The evaluation results were expressed as an index with the value of Example 1 set to 100. A higher index value indicates better performance in harsh road conditions.

[0050] Patterned block durability (cut resistance)

[0051] Each test tire was assembled onto a 17×8J rim, with the tire pressure set to 350 kPa, and mounted on a test vehicle (four-wheel drive SUV). After driving 1000 km on an off-road durability track, the total length of cuts incurred on the sidewalls was measured. The evaluation results were expressed as an exponent with the reciprocal of the measured value from Example 1 set to 100. The larger the exponent value, the smaller the total length of cuts, indicating better tread block durability (cut resistance).

[0052] [Table 1]

[0053]

[0054] [Table 2]

[0055]

[0056] As shown in Tables 1-2, the pneumatic tires of Examples 1-12, compared to the conventional Example 1, improved off-road capability and tread block durability, achieving a balanced performance across these aspects. On the other hand, Comparative Example 1 has a structure where two shoulder tread blocks and one sidewall tread block are adjacent, thus improving tread block durability compared to the conventional Example 1. However, due to the absence of curved sidewall grooves, the improvement in off-road capability was not fully achieved. Comparative Example 2 uses straight sidewall grooves instead of curved ones, therefore, it cannot sufficiently improve off-road capability.

[0057] Explanation of reference numerals in the attached figures

[0058] 1: Fetal face

[0059] 2: Side wall portion

[0060] 3: Bead area

[0061] 4: Fetal body layer

[0062] 5: Tire bead core

[0063] 6: Tire sidewall core

[0064] 7: Belt layer

[0065] 8: Belt reinforcement layer

[0066] 10: Main slot

[0067] 11: Shoulder lateral grooves

[0068] 12: Tire shoulder tread blocks

[0069] 13: Sidewall tread blocks

[0070] 14: Sidewall groove

[0071] 15: Protrusion

[0072] 20: Curved sidewall groove

[0073] 21: Connecting part

[0074] 22: Turnback Section

[0075] 31: First recess

[0076] 32: Second concave portion

[0077] 33: Protrusion at the bottom of the trough

[0078] CL: Tire Equator

[0079] B: Patterned Block Group

Claims

1. A tire comprising a tread portion extending in an annular shape along the tire circumference and a pair of sidewall portions disposed on both sides of said tread portion, characterized in that, On the surface of the tread, there is a pair of main grooves extending circumferentially along both sides of the tire equator. The tire shoulder region located outside the main groove in the tire width direction is provided with: multiple shoulder lateral grooves extending outward from the main groove in the tire width direction and arranged at intervals in the tire circumferential direction; and multiple shoulder tread blocks, which are divided by the main groove and the shoulder lateral grooves and arranged along the tire circumferential direction. A plurality of sidewall tread blocks are provided in the sidewall region adjacent to the outer side of the tire shoulder region in the tire width direction. A sidewall tread block is positioned on the outer side of two or more adjacent shoulder tread blocks in the tire circumferential direction. When the combination of these two or more shoulder tread blocks and one sidewall tread block is defined as a tread block group, A curved sidewall groove terminating within the sidewall tread block is formed on the extension line of the shoulder lateral groove between a pair of shoulder tread blocks included in the tread block group. The curved sidewall groove includes: a connecting portion extending radially inward from the end position of the shoulder lateral groove; and a folded-back portion bending towards one side of the tire circumferential direction from the end of the connecting portion radially inward and extending radially outward from the tire.

2. The tire according to claim 1, characterized in that, A first recess is formed at a position adjacent to the tire circumferential side of the connecting portion, which is recessed from the surface of the sidewall tread block and higher than the curved sidewall groove. A second recess is formed at a position adjacent to the tire radially outer side of the folded portion, which is recessed from the surface of the sidewall tread block and higher than the curved sidewall groove.

3. The tire according to claim 2, characterized in that, The indentation of the first and second recesses relative to the surface of the sidewall tread block is 0.5 mm to 2.5 mm.

4. The tire according to claim 2 or 3, characterized in that, The area of ​​the second recess is 10% to 40% of the area of ​​the first recess.

5. The tire according to any one of claims 1 to 4, characterized in that, The groove width of the folded-back portion is smaller than the groove width of the connecting portion.

6. The tire according to any one of claims 1 to 5, characterized in that, The depth of the curved sidewall groove is 0.5mm to 3mm.

7. The tire according to any one of claims 1 to 6, characterized in that, The bottom of the shoulder lateral groove has a groove bottom protrusion that rises from the bottom of the groove.

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