tire

Abstract

To provide a tire that can improve on-snow performance at the time of travelling on a compacted snow road surface.SOLUTION: A tread part 2 has: a groove 3 comprising a first groove wall 3a and a second groove wall 3b arranged opposing to each other; at least one first recessed part 5 recessed partially from the first groove wall 3a: and at least one second recessed part 6 recessed partially from the second groove wall 3b. Depths d1 and d2 from a grounding surface 2a of the first recessed part 5 and the second recessed part 6 respectively are smaller than a groove depth D1 of the groove 3. The first recessed part 5 has, on the grounding surface 2a, a first opening portion 5a positioned at the first groove wall 3a and a first end portion 5b extending in a nearly parallel to the first opening portion 5a, at a position farthest away from the first opening portion 5a. The second recessed part 6 has, on the grounding surface 2a, a second opening portion 6a positioned at the second groove wall 3b and a second end portion 6b extending in a nearly parallel to the second opening portion 6a, at a position farthest away from the second opening portion 6a. The first end portion 5b and the second end portion 6b are provided at positions which are not opposing to each other, through the groove 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a tire having a tread portion having a contact surface. [Background technology]

[0002] Conventionally, tires with multiple grooves formed therein for improving performance on snow have been known. For example, Patent Document 1 listed below proposes a pneumatic tire with notches formed at the intersections of the main grooves and lug grooves to improve snow column shear force. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-199119 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even with the tire of Patent Document 1, for example, when traveling on a packed snow road, the snow column shear force may decrease, and further improvement in on-snow performance has been desired.

[0005] The present disclosure has been devised in view of the above circumstances, and has as its main object to provide a tire that can improve on-snow performance when traveling on packed snow roads. [Means for solving the problem]

[0006] The present disclosure relates to a tire having a tread portion with a contact surface, wherein the tread portion has a groove with a first groove wall and a second groove wall facing each other, at least one first recess that is partially recessed from the first groove wall, and at least one second recess that is partially recessed from the second groove wall, wherein the depths of the first recess and the second recess from the contact surface are each smaller than the groove depth of the groove, wherein the first recess has, in the contact surface, a first opening located in the first groove wall and a first end extending substantially parallel to the first opening at a position farthest from the first opening, and the second recess has, in the contact surface, a second opening located in the second groove wall and a second end extending substantially parallel to the second opening at a position farthest from the second opening, wherein the first end and the second end are located in positions that do not face each other across the groove. [Effects of the Invention]

[0007] By having the above-described configuration, the tire of the present disclosure can compact snow with the first recesses and the second recesses even on packed snow roads, thereby improving on-snow performance when driving on packed snow roads. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a development view schematically illustrating a tread portion of an embodiment of a tire according to the present disclosure. [Figure 2] FIG. [Figure 3] FIG. 3 is a plan view of the groove of FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along the line AA in FIG. [Figure 5] FIG. 10 is a cross-sectional perspective view of a groove of the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along the line BB in FIG. 5. [Figure 7] FIG. 10 is a cross-sectional perspective view of a groove of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. Fig. 1 is a development view that schematically shows a tread portion 2 of a tire 1 of this embodiment. As shown in Fig. 1, the tire 1 of this embodiment has a tread portion 2 having a contact surface 2a. The tread portion 2 of this embodiment has a plurality of grooves 3 and block-shaped land portions 4 that are divided by the plurality of grooves 3.

[0010] The tire 1 can be suitably used, for example, as a winter pneumatic tire that has excellent performance on snow and ice. The tire 1 is not limited to a winter pneumatic tire, and can be used for various tires 1, such as a heavy-duty pneumatic tire and a non-pneumatic tire that is not filled with pressurized air.

[0011] The groove 3 has, for example, a first groove wall 3a and a second groove wall 3b facing each other. The tread portion 2 of this embodiment has at least one first recessed portion 5 partially recessed from the first groove wall 3a and at least one second recessed portion 6 partially recessed from the second groove wall 3b. The tread portion 2 as described above can compact snow by the grooves 3, the first recessed portion 5, and the second recessed portion 6, thereby improving the on-snow performance of the tire 1. Furthermore, because the first recessed portion 5 and the second recessed portion 6 are partially recessed, a decrease in the noise performance of the tire 1 can be suppressed.

[0012] Fig. 2 is a cross-sectional perspective view of the groove 3, and Fig. 3 is a plan view of the groove 3 of Fig. 2. Fig. 4 is a cross-sectional view taken along line AA of Fig. 3. As shown in Figs. 2 to 4, the depths d1 and d2 of the first recessed portion 5 and the second recessed portion 6 from the ground contact surface 2a in this embodiment are each smaller than the groove depth D1 of the groove 3. Such first recessed portion 5 and second recessed portion 6 can compact snow even when traveling on packed snow roads, thereby helping to improve the on-snow performance of the tire 1.

[0013] The first recess 5 of this embodiment has, in the ground contact surface 2a, a first opening 5a located in the first groove wall 3a and a first end 5b extending substantially parallel to the first opening 5a at a position farthest from the first opening 5a. Such a first recess 5 can efficiently compact snow between the first opening 5a and the first end 5b, thereby improving the on-snow performance of the tire 1. Furthermore, the first end 5b can exert an edge effect in cooperation with the first groove wall 3a, which helps to improve the on-snow performance of the tire 1. Here, substantially parallel in this specification means that the angle between the two is 5° or less.

[0014] The second recess 6 of this embodiment has, in the ground contact surface 2a, a second opening 6a located in the second groove wall 3b and a second end 6b extending substantially parallel to the second opening 6a at a position farthest from the second opening 6a. Such a second recess 6 can efficiently compact snow between the second opening 6a and the second end 6b, improving the on-snow performance of the tire 1. In addition, the second end 6b can exert an edge effect in cooperation with the second groove wall 3b, which helps to improve the on-snow performance of the tire 1.

[0015] The first end portion 5b and the second end portion 6b of this embodiment are provided in positions that do not face each other across the groove 3. Such first recessed portion 5 and second recessed portion 6 suppress the occurrence of snow clogging, thereby improving the on-snow performance of the tire 1. Furthermore, the first recessed portion 5 and second recessed portion 6 are suitable for compacting snow over a wide area on packed snow roads, which helps improve the on-snow performance of the tire 1. Therefore, the tire 1 of this embodiment can improve on-snow performance when running on packed snow roads.

[0016] 1, the grooves 3 include, for example, a plurality of circumferential grooves 7 extending in the tire circumferential direction and a plurality of lateral grooves 8 extending in the tire axial direction. It is desirable that the land portions 4 are provided with a plurality of sipes 9 extending in the tire axial direction.

[0017] Here, the sipes 9 are narrow grooves with a width of 2 mm or less, and are distinguished from the grooves 3. It is desirable to provide at least one sipe 9 in each block-shaped land portion 4. Such a tread portion 2 can exert snow column shear force and edge effect by the grooves 3 and sipes 9, thereby improving the on-snow performance of the tire 1.

[0018] Although FIG. 1 shows a schematic example in which the circumferential grooves 7, the lateral grooves 8, and the sipes 9 extend linearly, the circumferential grooves 7, the lateral grooves 8, and the sipes 9 are not limited to this configuration and may each extend in a zigzag pattern.

[0019] The circumferential grooves 7 include, for example, a pair of crown circumferential grooves 7A arranged along the tire equator C, and shoulder circumferential grooves 7B arranged between the crown circumferential grooves 7A and the tread ground contact edge Te.

[0020] Here, the tread edge Te is the axially outermost contact point when the tire 1 is in a normal state and is subjected to a normal load and contacts the ground on a flat surface with a camber angle of 0°. The tire equator C is the center position of the axially opposite tread edges Te.

[0021] In the case where the tire 1 is a pneumatic tire, the "normal state" refers to a state in which the tire 1 is mounted on a normal rim, adjusted to a normal internal pressure, and no load is applied. Unless otherwise specified below, the dimensions of each part of the tire 1 are values measured in this normal state.

[0022] If there is a standard system that includes the standard on which tire 1 is based, a "genuine rim" is a rim that is determined for each tire by that standard, for example, a "standard rim" for JATMA, a "design rim" for TRA, or a "measuring rim" for ETRTO. If there is no standard system that includes the standard on which tire 1 is based, a "genuine rim" is a rim that can be mounted on a rim and does not cause air leakage, and that has the smallest rim diameter and narrowest rim width among those rims.

[0023] "Normal internal pressure" is the air pressure set for each tire by a standard set by each standard, if there is one that includes the standard on which tire 1 is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE." If there is no standard set that includes the standard on which tire 1 is based, "normal internal pressure" is the air pressure set for each tire by the manufacturer, etc.

[0024] "Normal load" is the load determined for each tire by a standard system that includes the standard on which tire 1 is based, if there is such a system. For JATMA, it is "Maximum Load Capacity," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is "LOAD CAPACITY." If there is no standard system that includes the standard on which tire 1 is based, "Normal load" is the load determined for each tire by the manufacturer, etc.

[0025] The land portion 4 includes, for example, a crown land portion 4A defined between a pair of crown circumferential grooves 7A, a middle land portion 4B defined between the crown circumferential groove 7A and the shoulder circumferential groove 7B, and a shoulder land portion 4C defined between the shoulder circumferential groove 7B and the tread ground contact edge Te.

[0026] The lateral grooves 8 include, for example, crown lateral grooves 8A that divide the crown land portion 4A into blocks, middle lateral grooves 8B that divide the middle land portion 4B into blocks, and shoulder lateral grooves 8C that divide the shoulder land portion 4C into blocks. Figure 1 illustrates an example in which the first recesses 5 and the second recesses 6 are formed in the shoulder lateral grooves 8C.

[0027] 2 and 4, the depths d1 and d2 of the first recessed portion 5 and the second recessed portion 6 are each preferably 10% to 70% of the groove depth D1. By making the depths d1 and d2 10% or more of the groove depth D1, it is possible to prevent early deterioration of the on-snow performance of the tire 1 even when the tire 1 is worn. From this perspective, the depths d1 and d2 of the first recessed portion 5 and the second recessed portion 6 are more preferably 20% or more of the groove depth D1, and even more preferably 30% or more of the groove depth D1.

[0028] By making the depths d1 and d2 70% or less of the groove depth D1, it is possible to prevent a decrease in the snow compacting effect of the first recesses 5 and the second recesses 6. From this perspective, the depths d1 and d2 of the first recesses 5 and the second recesses 6 are more preferably 60% or less of the groove depth D1, and even more preferably 50% or less of the groove depth D1. It is desirable that the depth d1 of the first recesses 5 and the depth d2 of the second recesses 6 are approximately equal.

[0029] 3, the shape of the first recess 5 on the ground contact surface 2a is preferably a polygon including a first opening 5a and a first end 5b. In this embodiment, the shape of the first recess 5 on the ground contact surface 2a is a trapezoid. This type of first recess 5 can apply force to the snow in the first recess 5 from multiple sides, allowing the snow to be efficiently compacted.

[0030] The shape of the second recess 6 on the ground contact surface 2a is preferably a polygon including the second opening 6a and the second end 6b. In this embodiment, the shape of the second recess 6 on the ground contact surface 2a is a trapezoid. This type of second recess 6 can apply force to the snow in the second recess 6 from multiple sides, allowing the snow to be efficiently compacted.

[0031] The length L2 of the first end 5b is preferably equal to or less than the length L1 of the first opening 5a. The length L4 of the second end 6b is preferably equal to or less than the length L3 of the second opening 6a. Such first recessed portion 5 and second recessed portion 6 more effectively suppress the occurrence of snow clogging, thereby further improving the on-snow performance of the tire 1.

[0032] The difference (L1-L2) between the length L1 of the first opening 5a and the length L2 of the first end 5b is preferably 4 mm or less. The difference (L3-L4) between the length L3 of the second opening 6a and the length L4 of the second end 6b is preferably 4 mm or less. By ensuring that the differences (L1-L2) and (L3-L4) are 4 mm or less, the length L2 of the first end 5b and the length L4 of the second end 6b can be sufficiently ensured, which helps improve the on-snow performance of the tire 1.

[0033] The distance L5 between the first end 5b and the first opening 5a is preferably 10% to 50% of the distance L6 between the first end 5b and the second groove wall 3b. When the distance L5 is 10% or more of the distance L6, the snow compacting effect of the first recess 5 can be sufficiently exhibited. From this perspective, the distance L5 between the first end 5b and the first opening 5a is more preferably 15% or more of the distance L6 between the first end 5b and the second groove wall 3b.

[0034] Setting the distance L5 to 50% or less of the distance L6 makes it possible to prevent snow from clogging the first recessed portions 5 and also to prevent rubber chipping between adjacent first recessed portions 5. From this perspective, the distance L5 between the first end portion 5b and the first opening portion 5a is more preferably 35% or less of the distance L6 between the first end portion 5b and the second groove wall 3b.

[0035] The distance L7 between the second end 6b and the second opening 6a is preferably 10% to 50% of the distance L8 between the second end 6b and the first groove wall 3a. When the distance L7 is 10% or more of the distance L8, the snow compacting effect of the second recess 6 can be sufficiently exhibited. From this perspective, the distance L7 between the second end 6b and the second opening 6a is more preferably 15% or more of the distance L8 between the second end 6b and the first groove wall 3a.

[0036] Setting the distance L7 to 50% or less of the distance L8 makes it possible to prevent snow from clogging the second recessed portions 6 and also to prevent chipping of the rubber between adjacent second recessed portions 6. From this perspective, the distance L7 between the second end portion 6b and the second opening portion 6a is more preferably 35% or less of the distance L8 between the second end portion 6b and the first groove wall 3a.

[0037] It is desirable that the distance L5 between the first end 5b and the first opening 5a be equal to the distance L7 between the second end 6b and the second opening 6a. Such first recessed portion 5 and second recessed portion 6 can compact snow evenly on both sides of the groove 3, which helps to improve the performance of the tire 1 on snow.

[0038] 2 and 4, the first recess 5 has, for example, a first bottom surface 5c that defines the radially inner side of the tire. The first bottom surface 5c preferably includes a parallel surface that is substantially parallel to the ground contact surface 2a. In this embodiment, the first bottom surface 5c is configured as a parallel surface that is substantially parallel to the ground contact surface 2a. Such a first recess 5 can efficiently compact snow between the road surface and the first bottom surface 5c, which helps improve the on-snow performance of the tire 1.

[0039] The second recess 6 has, for example, a second bottom surface 6c that defines the radially inner side of the tire. The second bottom surface 6c preferably includes a parallel surface that is approximately parallel to the ground contact surface 2a. In this embodiment, the second bottom surface 6c is configured as a parallel surface that is approximately parallel to the ground contact surface 2a. Such a second recess 6 can efficiently compact snow between the road surface and the second bottom surface 6c, which helps to improve the on-snow performance of the tire 1.

[0040] Fig. 5 is a cross-sectional perspective view of a groove 20 of the second embodiment, and Fig. 6 is a cross-sectional view taken along line BB in Fig. 5. The same components as those in the above-described embodiments are given the same reference numerals, and their description will be omitted. As shown in Figs. 5 and 6, the groove 20 of the second embodiment is provided in the tread portion 2. The groove 20 may be, for example, a different groove 20 provided in the tread portion 2 in which the above-described groove 3 is provided, or may be a groove 20 provided in the tread portion 2 of a tire 1 different from the one in which the groove 3 is provided.

[0041] The groove 20 has, for example, a first groove wall 20a and a second groove wall 20b facing each other. The tread portion 2 of the second embodiment has at least one first recess 21 partially recessed from the first groove wall 20a and at least one second recess 22 partially recessed from the second groove wall 20b.

[0042] In the second embodiment, the depths d3 and d4 of the first recessed portion 21 and the second recessed portion 22 from the ground contact surface 2a are each smaller than the groove depth D2 of the groove 20. Such first recessed portion 21 and second recessed portion 22 can compact snow even when traveling on packed snow roads, which helps to improve the on-snow performance of the tire 1.

[0043] The first recess 21 of the second embodiment has a first opening 21a located in the first groove wall 20a in the ground contact surface 2a, and a first end 21b extending substantially parallel to the first opening 21a at a position farthest from the first opening 21a. The first recess 21 preferably further has a first bottom surface 21c defining the radially inner side of the tire.

[0044] The second recess 22 of the second embodiment has a second opening 22a located in the second groove wall 20b in the ground contact surface 2a, and a second end 22b extending substantially parallel to the second opening 22a at a position farthest from the second opening 22a. The second recess 22 preferably further has a second bottom surface 22c defining the radially inner side of the tire.

[0045] 5, the first end portion 21b and the second end portion 22b of the second embodiment are provided in positions that do not face each other across the groove 20, similar to the first recessed portion 5 and the second recessed portion 6 described above. Such first recessed portion 21 and second recessed portion 22 can suppress snow clogging therein, improving the on-snow performance of the tire 1. Furthermore, the first recessed portion 21 and second recessed portion 22 are suitable for compacting snow over a wide area on packed snow road surfaces, and are useful for improving the on-snow performance of the tire 1.

[0046] 6, in the groove 20 of the second embodiment, the groove width W1 on the radially inner side of the first bottom surface 21c is larger than the groove width W2 at a depth d3 of the first bottom surface 21c. The groove 20 has, for example, a substantially rectangular cross section on the radially inner side of the first bottom surface 21c. That is, in the second embodiment, the groove width W1 at a groove depth D2 is larger than the groove width W2 at a depth d3.

[0047] It is desirable that the depth d3 of the first bottom surface 21c and the depth d4 of the second bottom surface 22c are approximately equal. Therefore, in the second embodiment, the groove width W1 at the groove depth D2 is greater than the groove width W2 at the depth d4. Such a groove 20 can maintain a constant groove volume even as wear progresses, preventing the tire 1's on-snow performance from rapidly deteriorating due to wear. This effect is particularly effective when the imaginary groove width W3 at the contact patch 2a is small, for example, about 4 to 5 mm. Here, the imaginary groove width W3 is the distance between the first end 21b and the second end 22b in a direction perpendicular to the longitudinal direction of the groove 20.

[0048] The difference (W1-W2) between the groove width W1 at groove depth D2 and the groove width W2 at depths d3 and d4 is preferably 4 mm or less. By keeping the difference (W1-W2) 4 mm or less, demolding after vulcanization molding is easy and chipping of the rubber during demolding can be suppressed.

[0049] The cross-sectional shape of the groove 20 radially inward of the first bottom surface 21c is not limited to that shown in the figure, and various shapes such as a circle, an ellipse, a triangle, a trapezoid, etc. may be adopted.

[0050] 5 and 6, the first bottom surface 21c preferably includes a parallel surface that is substantially parallel to the ground contact surface 2a. The first bottom surface 21c of the second embodiment is configured as a parallel surface that is substantially parallel to the ground contact surface 2a. Such a first recess 21 can efficiently compact snow between the road surface and the first bottom surface 21c, which helps to improve the on-snow performance of the tire 1.

[0051] The second bottom surface 22c desirably includes a parallel surface that is approximately parallel to the ground contact surface 2a. In this embodiment, the second bottom surface 22c is configured as a parallel surface that is approximately parallel to the ground contact surface 2a. Such a second recess 22 can efficiently compact snow between the road surface and the second bottom surface 22c, which helps to improve the on-snow performance of the tire 1.

[0052] Fig. 7 is a cross-sectional perspective view of a groove 30 of a third embodiment. The same components as those of the above-described embodiments are assigned the same reference numerals, and their description will be omitted. As shown in Fig. 7, the groove 30 of the third embodiment is provided in the tread portion 2. The groove 30 may be, for example, a different groove 30 provided in the tread portion 2 in which the above-described grooves 3 and 20 are provided, or may be a groove 30 provided in the tread portion 2 of a tire 1 different from that in which the grooves 3 and 20 are provided.

[0053] The groove 30 has, for example, a first groove wall 30a and a second groove wall 30b facing each other. The tread portion 2 of the third embodiment has at least one first recess 31 partially recessed from the first groove wall 30a and at least one second recess 32 partially recessed from the second groove wall 30b.

[0054] The depths d5 and d6 of the first recessed portion 31 and the second recessed portion 32 from the ground contact surface 2a in the third embodiment are each smaller than the groove depth D3 of the groove 30. Such first recessed portion 31 and second recessed portion 32 can compact snow even when traveling on packed snow roads, which helps to improve the on-snow performance of the tire 1.

[0055] The first recess 31 of the third embodiment has a first opening 31a located in the first groove wall 30a in the ground contact patch 2a, and a first end 31b extending substantially parallel to the first opening 31a at a position farthest from the first opening 31a. The first recess 31 preferably further has a first bottom surface 31c defining the radially inner side of the tire.

[0056] The second recess 32 of the third embodiment has a second opening 32a located in the second groove wall 30b in the ground contact patch 2a, and a second end 32b extending substantially parallel to the second opening 32a at a position farthest from the second opening 32a. The second recess 32 preferably further has a second bottom surface 32c defining the radially inner side of the tire.

[0057] The first end 31b and the second end 32b of the third embodiment are provided in positions that do not face each other across the groove 30. Such first recessed portion 31 and second recessed portion 32 can suppress snow clogging inside them, improving the on-snow performance of the tire 1. Furthermore, the first recessed portion 31 and second recessed portion 32 are suitable for compacting snow over a wide area on packed snow road surfaces, and are useful for improving the on-snow performance of the tire 1.

[0058] The first bottom surface 31c includes, for example, protrusions 33 that protrude radially outward from a plane that is substantially parallel to the ground contact surface 2a. Although not shown, the second bottom surface 32c also includes, for example, protrusions 33 that protrude radially outward from a plane that is substantially parallel to the ground contact surface 2a. The protrusions 33 on the first bottom surface 31c and the second bottom surface 32c can suppress the movement of snow, allowing the snow to be compacted more effectively.

[0059] The protrusion 33 of the third embodiment includes two adjacent inclined surfaces 33a and a peak 33b between the two inclined surfaces 33a. Such a protrusion 33 can pierce the peak 33b into the snow, more reliably suppressing the movement of snow and more effectively compacting the snow.

[0060] The height h of the apex 33b in the tire radial direction from the end of the inclined surface 33a on the inner side in the tire radial direction is preferably 10% to 40% of the depths d5, d6 of the first recessed portion 31 and the second recessed portion 32. When the height h is 10% or more of the depths d5, d6, the piercing effect of the apex 33b can be reliably exerted. From this perspective, the height h of the apex 33b is more preferably 15% or more of the depths d5, d6 of the first recessed portion 31 and the second recessed portion 32.

[0061] By setting the height h to 40% or less of the depths d5 and d6, it is possible to prevent a decrease in the volumes of the first recesses 31 and the second recesses 32. From this perspective, the height h of the tops 33b is more preferably 35% or less of the depths d5 and d6 of the first recesses 31 and the second recesses 32.

[0062] The angle θ formed by two adjacent inclined surfaces 33a is preferably 105 to 135°. When the angle θ is 105° or more, the piercing effect of the top portion 33b can be reliably exerted. From this perspective, the angle θ formed by the inclined surfaces 33a is more preferably 110° or more.

[0063] By setting the angle θ to 135° or less, it is possible to prevent a decrease in the volumes of the first recess 31 and the second recess 32. From this perspective, the angle θ formed by the inclined surface 33a is more preferably 130° or less.

[0064] The shape of the protrusions 33 is not limited to the illustrated embodiment, and may be, for example, rectangular or wavy when viewed from the groove 30. Furthermore, a plurality of protrusions 33 may be provided in each of the first recess 31 and the second recess 32, for example.

[0065] Although particularly preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments and can be modified and implemented in various forms. [Example]

[0066] Tires having shoulder lateral grooves as shown in Figures 2, 5, and 7 were prototyped based on the specifications in Tables 1 and 2. As a comparative example, a tire without the first recessed portion and the second recessed portion was prototyped. The prototype tires were used to test their snow performance when running on packed snow roads. The common specifications and test methods are as follows:

[0067] <Common specifications> Tire size: LT265 / 70R18 Air pressure: 550kPa Test vehicle: Large SUV

[0068] <Snow performance> The prototype tires were mounted on all wheels of a test vehicle, and the test driver evaluated the acceleration / deceleration response and grip characteristics on a test course with a packed snow surface. The results were scored based on a score of 100 for Comparative Example 1, with a higher score indicating better on-snow performance.

[0069] The test results are shown in Tables 1 and 2. [Table 1]

[0070] [Table 2]

[0071] As a result of the test, it was confirmed that the tires of the examples were evaluated as being better than those of the comparative examples when running on packed snow roads, and had superior performance on snow.

[0072] [Note] The present disclosure includes the following aspects.

[0073] The present disclosure (1) is a tire having a tread portion with a contact surface, the tread portion having a groove with a first groove wall and a second groove wall facing each other, at least one first recess that is partially recessed from the first groove wall, and at least one second recess that is partially recessed from the second groove wall, the depths of the first recess and the second recess from the contact surface are each smaller than the groove depth of the groove, the first recess has a first opening located in the first groove wall at the contact surface and a first end extending substantially parallel to the first opening at a position farthest from the first opening, the second recess has a second opening located in the second groove wall at the contact surface and a second end extending substantially parallel to the second opening at a position farthest from the second opening, the first end and the second end being located in positions that do not face each other across the groove.

[0074] The present disclosure (2) is a tire described in the present disclosure (2), wherein the length of the first end is equal to or less than the length of the first opening, and the length of the second end is equal to or less than the length of the second opening.

[0075] The present disclosure (3) is the tire according to the present disclosure (1) or (2), wherein the depths of the first recess and the second recess are each 10% to 70% of the groove depth.

[0076] The present disclosure (4) is a tire according to any one of the present disclosures (1) to (3), wherein the distance between the first end and the first opening is 10% to 50% of the distance between the first end and the second groove wall.

[0077] The present disclosure (5) is a tire according to any one of the present disclosures (1) to (4), wherein the distance between the first end and the first opening is equal to the distance between the second end and the second opening.

[0078] The present disclosure (6) is a tire according to any one of the present disclosures (1) to (5), wherein the shape of the first recess on the contact surface is a polygonal shape including the first opening and the first end.

[0079] The present disclosure (7) is a tire according to any one of the present disclosures (1) to (6), wherein the first recess has a first bottom surface that defines the radially inner side of the tire, and the first bottom surface includes a parallel surface that is approximately parallel to the contact patch.

[0080] The present disclosure (8) is a tire according to any one of the present disclosures (1) to (6), wherein the first recess has a first bottom surface that defines the radially inner side of the tire, and the first bottom surface includes a protrusion that protrudes radially outward from a parallel plane that is approximately parallel to the contact patch.

[0081] The present disclosure (9) is the tire according to the present disclosure (8), wherein the protrusion includes two inclined surfaces adjacent to each other and a peak between the two inclined surfaces.

[0082] The present disclosure (10) is the tire according to the present disclosure (9), wherein the height of the apex in the tire radial direction from the end of the inclined surface on the inner side in the tire radial direction is 10% to 40% of the depth of the first recess.

[0083] The present disclosure (11) is a tire according to any one of the present disclosures (7) to (10), wherein the groove has a groove width radially inward of the first bottom surface of the tire that is greater than the groove width at a depth position of the first bottom surface. [Explanation of symbols]

[0084] 2 Tread section 2a Ground plane 3 grooves 3a 1st groove wall 3b 2nd groove wall 5 First recess 5a 1st opening 5b 1st end 6 Second recess 6a 2nd opening 6b Second end

Claims

1. A tire having a tread portion with a contact surface, The tread portion has a groove having a first groove wall and a second groove wall opposed to each other, at least one first recessed portion partially recessed from the first groove wall, and at least one second recessed portion partially recessed from the second groove wall, a depth of the first recess and a depth of the second recess from the ground surface are each smaller than a depth of the groove; the first recess has, in the ground contact surface, a first opening located in the first groove wall, and a first end extending substantially parallel to the first opening at a position farthest from the first opening; the second recess has, on the ground surface, a second opening located in the second groove wall and a second end extending substantially parallel to the second opening at a position farthest from the second opening, the first end and the second end are provided at positions that do not face each other across the groove, The groove in which the first recessed portion and the second recessed portion are formed is a lateral groove extending in the tire axial direction. tire.

2. a length of the first end portion is equal to or less than a length of the first opening portion; The tire of claim 1 , wherein the length of the second end is less than or equal to the length of the second opening.

3. 3. The tire according to claim 1, wherein the depths of the first recess and the second recess are each 10% to 70% of the groove depth.

4. 4. The tire according to claim 1, wherein the distance between the first end and the first opening is 10% to 50% of the distance between the first end and the second groove wall.

5. 5. A tire according to claim 1, wherein the distance between the first end and the first opening is equal to the distance between the second end and the second opening.

6. The tire according to claim 1 , wherein the first recessed portion has a polygonal shape in the ground contact surface that includes the first opening and the first end portion.

7. the first recess has a first bottom surface that defines an inner side in the tire radial direction, The tire according to claim 1 , wherein the first bottom surface includes a parallel surface that is substantially parallel to the ground contact surface.

8. the first recess has a first bottom surface that defines an inner side in the tire radial direction, The tire according to claim 1 , wherein the first bottom surface includes a protrusion that protrudes radially outward from a plane that is substantially parallel to the ground contact surface.

9. The tire of claim 8 , wherein the protrusion includes two adjacent inclined surfaces and a peak between the two inclined surfaces.

10. The tire according to claim 9, wherein a height of the apex in the tire radial direction from an end of the inclined surface on an inner side in the tire radial direction is 10% to 40% of the depth of the first recessed portion.

11. The tire according to claim 7 , wherein the groove has a groove width on a radially inner side of the first bottom surface that is larger than the groove width at a depth position of the first bottom surface.

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