Tire

Abstract

To achieve both reduction of rolling resistance and improvement of wet traction performance.SOLUTION: Provided is a tire having one or more circumferential fine major grooves 21 whose groove width W1 opening to a tread surface of a tread part 20 is more than 1.0 mm and 4.0 mm or less, and which extend in a tire circumferential direction, and a plurality of sipes 24 communicating with the circumferential fine major grooves 21. The circumferential fine major grooves 21 include a widening part 212 whose groove width is widened in a region where a groove depth from a surface of the tread part 20 is 30% or more of the maximum groove depth, and a plurality of notch parts 213 disposed at a distance in the tire circumferential direction, and communicating from the surface of the tread part 20 to the widening part 212 by expanding on one side of a tire width direction. The sipes 24 communicate with the notch parts 213.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a tire having circumferential narrow grooves with widened portions at the groove bottoms where the groove width is widened.

Background Art

[0002] In recent years, in order to improve the rolling resistance coefficient (RRC), a rib-based block pattern in which a rib row partitioned by a plurality of circumferential narrow grooves is divided by lug grooves or sipes has been explored, and further, a tire having a tread portion in which block rows are concentrated and arranged in the center portion has been sought. In this type of tire, since the groove volume decreases due to the circumferential narrow grooves and the wet traction performance deteriorates, a tire has been proposed in which an enlarged portion with an enlarged groove width is formed at the groove bottom of the circumferential narrow grooves to secure the groove volume and thereby secure the wet traction performance (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in order to connect a sipe to a circumferential narrow groove, it is necessary to provide a reinforcing portion at the connection portion between the circumferential narrow groove and the sipe in the mold in order to maintain the strength of the mold for molding the tire. For this reason, in the connection portion between the circumferential narrow groove and the sipe of the tire, a duct, which is a space corresponding to the reinforcing portion of the mold, is formed to extend in the thickness direction of the tread portion. However, in the conventional configuration, problems such as a decrease in the contact area of the tread portion due to the duct and a deterioration in rolling resistance due to a decrease in block rigidity were assumed, and there was sufficient room for improvement.

[0005] The present invention has been made in view of the above, and an object thereof is to provide a tire that achieves both an improvement in wet traction performance and a reduction in rolling resistance.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, the tire according to the present invention has a groove width of an opening portion that opens on the surface of the tread portion exceeding 1.0 mm and being 4.0 mm or less, one or more circumferential grooves extending in the tire circumferential direction, and a plurality of widthwise sipes communicating with the circumferential grooves. At least one circumferential groove has a widened portion where the groove width is wider than the opening portion in a region where the groove depth from the surface of the tread portion is 30% or more of the maximum groove depth, and a plurality of notches provided at intervals in the tire circumferential direction and bulging on one side in the tire width direction and communicating from the surface of the tread portion to the widened portion. At least one notch has a widthwise sipe connected thereto.

[0007] In the above-described tire, the notch has an opening area on the surface of the tread portion of 1.5 mm 2 or more and 10.0 mm 2 or less, which is preferable.

[0008] In the above-described tire, it is preferable that the width Wa of the notch and the groove width W1 of the opening portion are within the range of 0.5 ≦ (Wa / W1) ≦ 2.0.

[0009] In the above-described tire, the number of notches provided in one circumferential groove is preferably 10 or more and 20 or less within the ground contact surface of the tread portion.

[0010] In the above-described tire, among the notches provided in one circumferential groove, the ratio of the number of notches bulging inward to the number of notches bulging outward in the tire width direction of the circumferential groove is preferably 0.2 or more and 1.0 or less.

[0011] In the tire described above, it is preferable that the maximum groove width W2 of the widened portion and the groove width W1 of the opening portion are within the range of 1.0 < (W2 / W1) ≤ 4.0, and the width Wb from the opening portion to the widened portion and the width Wa of the notch portion are within the range of 0.5 ≤ (Wa / Wb) ≤ 2.0.

[0012] In the tire described above, the groove depth H4 of the widthwise sipe preferably satisfies the relationship of H3 < H4 < 0.9H1 with respect to the depth H3 from the surface of the tread portion in the circumferential fine groove to the connecting portion between the notch portion and the widened portion and the maximum groove depth H1 of the circumferential fine groove.

[0013] In the tire described above, the widthwise sipe preferably includes a widened sipe widened at the bottom, and the maximum width and the height from the bottom surface of the widened sipe are 1.2 times or more and 3.0 times or less the groove width on the surface of the tread portion.

[0014] In the tire described above, a pair of circumferential main grooves arranged on the outer side in the tire width direction with the circumferential fine groove interposed therebetween in the tread portion and extending in the tire circumferential direction are provided, the groove width W4 of the circumferential main groove with respect to the grounding width TW of the tread portion is within the range of 3.0% or more and 5.0% or less, and the width TWc in the tire width direction of the land portion partitioned by the pair of circumferential main grooves and the grounding width TW are preferably within the range of 0.50 ≤ (TWc / TW) ≤ 0.60.

[0015] In the tire described above, it is preferable that all the circumferential fine grooves are in a zigzag shape that extends in the tire circumferential direction and repeatedly bends alternately in the tire width direction.

[0016] In the tire described above, the circumferential fine groove in the zigzag shape is preferably formed by alternately connecting long portions and short portions.

[0017] In the tire described above, it is preferable that at least one notch portion is provided on the convex side of the intersection of the long portion and the short portion.

[0018] In the tire described above, it is preferable that one long portion is provided with one or more notch portions bulging outward and inward in the tire width direction, respectively.

[0019] In the tire described above, it is preferable that in the zigzag-shaped circumferential fine grooves, the pitch length P2 of the circumferential fine grooves and the circumferential length L2 of the long portion in the tire circumferential direction are within the range of 0.85 ≦ (L2 / P2) ≦ 1.00.

[0020] In the tire described above, a pair of circumferential main grooves are provided on the outer side in the tire width direction with a plurality of circumferential fine grooves interposed therebetween in the tread portion and extending in the tire circumferential direction, and a first land portion partitioned by the plurality of circumferential fine grooves between the pair of circumferential main grooves, and a second land portion partitioned by the circumferential fine grooves and the circumferential main grooves, and the number N1 of the first blocks arranged in the tire circumferential direction by partitioning the first land portion by the width direction sipes, and the number N2 of the second blocks arranged in the tire circumferential direction by partitioning the second land portion by the width direction sipes are preferably within the range of 1.2 ≦ (N2 / N1) ≦ 2.0.

Advantages of the Invention

[0021] According to the present invention, the circumferential fine grooves have a widened portion where the groove width is wider than the opening portion in a region where the groove depth from the surface of the tread portion is 30% or more of the maximum groove depth, and a plurality of them are provided at intervals in the tire circumferential direction, and a notch portion bulging to one side in the tire width direction and communicating from the surface of the tread portion to the widened portion, and at least one notch portion is connected to the width direction sipes, so that it is possible to achieve both an improvement in wet traction performance and a reduction in rolling resistance.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The pneumatic tire according to the present embodiment is, for example, a pneumatic tire for a vehicle that travels long distances such as a truck. Note that the present invention is not limited by this embodiment. In addition, the constituent elements in the following embodiments include those that can be replaced by those skilled in the art and can be easily conceived, or those that are substantially the same.

[0024] FIG. 1 is a meridian cross-sectional view showing a main part of a pneumatic tire according to the present embodiment. In FIG. 1, a cross-sectional view of one-side region in the tire radial direction of the pneumatic tire 1 (hereinafter sometimes simply referred to as tire 1) is shown. FIG. 2 is a developed view showing a tread pattern of the pneumatic tire. FIG. 3 is a schematic view showing a cross-sectional shape of a circumferential thin main groove formed in the tread portion. FIG. 4 is a partially enlarged view schematically showing a tread surface of the tread portion showing the circumferential thin main groove and the sipe. FIG. 5 is a schematic view showing cross-sectional shapes of the circumferential thin main groove and the circumferential main groove formed in the tread portion. FIG. 6 is a schematic view showing a cross-sectional shape of the sipe formed in the tread portion. In the following description, the meridian cross-section means a cross-section when the tire is cut by a plane including the tire rotation axis (not shown). Further, the symbol CL is the tire equatorial plane, which means a plane passing through the center point of the tire in the tire rotation axis direction and perpendicular to the tire rotation axis. Further, the tire width direction means a direction parallel to the tire rotation axis, the inner side in the tire width direction means the side facing the tire equatorial plane CL in the tire width direction, and the outer side in the tire width direction means the side away from the tire equatorial plane CL in the tire width direction. The tire radial direction means a direction perpendicular to the tire rotation axis. Further, the inner side in the tire radial direction means the side facing the rotation axis in the tire radial direction, and the outer side in the tire radial direction means the side away from the rotation axis in the tire radial direction.

[0025] As shown in FIG. 1, the pneumatic tire 1 includes a pair of bead cores 11, 11, a carcass layer 13, a belt layer 14, a tread rubber 15 constituting the tread portion 20, sidewall rubbers 16, 16 constituting the left and right sidewall portions, and rim cushion rubbers 17, 17 constituting the left and right bead portions. The surface of the tread portion 20 constitutes a part of the contour of the pneumatic tire 1 and is formed as a tread surface 200 that contacts the road surface when the vehicle is running. The belt layer 14 has a configuration in which a plurality of belt plies are laminated. In FIG. 1, the belt layer 14 has a configuration in which a high-angle belt 141, a pair of crossed belt plies 142, 143, and a belt cover 144 are laminated. A bead filler may be provided on the outer side in the tire radial direction of the bead core 11. Note that the above-described tire internal structure shows a typical example in a pneumatic tire, but is not limited thereto.

[0026] As shown in FIG. 2, on the tread surface 200 of the tread portion 20, there are a first circumferential narrow main groove (circumferential narrow groove) 21A extending in the tire circumferential direction at the position of the tire equatorial plane CL, and on both sides of the tire equatorial plane CL, a pair of second circumferential narrow main grooves (circumferential narrow grooves) 21B extending in the tire circumferential direction at a position outside the tire width direction from the first circumferential narrow main groove 21A, and a pair of circumferential main grooves 22 extending in the tire circumferential direction at a position outside the tire width direction from the second circumferential narrow main groove 21B. These second circumferential narrow main grooves 21B and circumferential main grooves 22 are preferably arranged at symmetric positions with respect to the tire equatorial plane CL. When the first circumferential narrow main groove 21A and the second circumferential narrow main groove 21B are not distinguished, they are simply referred to as the circumferential narrow main groove 21.

[0027] The first circumferential narrow main groove 21A, the second circumferential narrow main groove 21B, and the circumferential main groove 22 are each five straight main grooves extending in the tire circumferential direction, and have a wear indicator defined by JATMA at the groove bottom. The pair of circumferential main grooves 22 are each shoulder main grooves located at the outermost side in the tire width direction, and are formed wider (larger) than the three circumferential narrow main grooves 21 arranged between these circumferential main grooves 22, 22. The groove width is the distance between the opposing wall surfaces of the groove. When chamfering is performed at the opening of the groove, the intersections of the extension line of the tread surface 200 and the extension line of the groove wall surface are respectively assumed, and the distance between these intersections is defined as the groove width. For the circumferential narrow main groove 21, it is preferable that the groove width W1 opening to the tread surface 200 when the tire is new is greater than 1.0 mm and not more than 4.0 mm, and more preferably 1.5 mm or more and 3.0 mm or less. Also, the circumferential main groove 22 is the groove having the largest groove width among the circumferential grooves formed in the tread portion 20. For the circumferential main groove 22, it is preferable that the groove width W4 when the tire is new is 8.0 mm or more and 15.0 mm or less, and more preferably 10 mm or more and 13 mm or less. In the present embodiment, a configuration is adopted in which three circumferential narrow main grooves 21 are provided between the pair of circumferential main grooves 22, but at least one circumferential narrow main groove 21 may be provided, and in particular, a configuration having two or more and four or less circumferential narrow main grooves 21 is preferable.

[0028] The tread portion 20 is partitioned into a plurality of land portions by forming a first circumferential direction narrow main groove 21A, a second circumferential direction narrow main groove 21B, and a circumferential direction main groove 22. Specifically, in the tread portion 20, a first land portion 31 extending in the tire circumferential direction is formed between the first circumferential direction narrow main groove 21A and the second circumferential direction narrow main groove 21B. The first land portion 31 is partitioned into a plurality of first blocks 31B by a plurality of sipes (width direction sipes) 24 extending in the tire width direction and penetrating the first land portion 31. That is, the first land portion 31 includes a plurality of first blocks 31B separated by the sipes 24 and arranged in the tire circumferential direction, and these plurality of first blocks 31B are configured as a block row. The first blocks 31B are repeatedly arranged at a predetermined pitch P in the tire circumferential direction. This pitch P refers to the distance when the first blocks 31B are repeatedly arranged in the tire circumferential direction, and is the sum of the distance of the first blocks 31B in the tire circumferential direction and the groove width of the sipes 24.

[0029] Also, in the tread portion 20, a second land portion 32 extending in the tire circumferential direction is formed between the second circumferential direction narrow main groove 21B and the circumferential direction main groove 22. The second land portion 32 is partitioned into a plurality of second blocks 32B by the sipes 24 extending in the tire width direction. That is, the second land portion 32 includes a plurality of second blocks 32B separated by the sipes 24 and arranged in the tire circumferential direction in the same manner as the first land portion 31, and these plurality of second blocks 32B are configured as a block row. The second blocks 32B are repeatedly arranged at a pitch (a half pitch (P / 2) corresponding to half of the pitch P of the first blocks 31B described above) shorter than the first blocks 31B.

[0030] The sipes 24 open to and connect (join) the adjacent first circumferential direction narrow main groove 21A and the second circumferential direction narrow main groove 21B, or the adjacent second circumferential direction narrow main groove 21B and the circumferential direction main groove 22, and are formed with a groove width narrower than the circumferential direction narrow main groove 21. Specifically, it is preferable that the groove width W5 opening to the tread surface 200 when the tire is new is 1.0 mm or less for the sipes 24.

[0031] In addition, in the tread portion 20, a shoulder land portion 33 extending in the tire circumferential direction is formed on the outer side in the tire width direction of the circumferential main groove 22. This shoulder land portion 33 is located in the shoulder portion of the tread portion 20. The shoulder land portion 33 may have a plurality of shoulder lug grooves (not shown) having one end connected to the circumferential main groove 22 and extending in the tire width direction, and may be configured to be partitioned into a plurality of shoulder blocks by these shoulder lug grooves.

[0032] In the example of FIG. 2, in the tread portion 20, all the sipes 24 extend in the tire width direction and include a plurality of rectangular first blocks 31B and second blocks 32B, and these plurality of first blocks 31B and second blocks 32B form a block pattern arranged in a staggered manner. Specifically, the first blocks 31B, 31B adjacent to each other across the first circumferential narrow main groove 21A are arranged with a 1 / 4 pitch (P / 4) displacement (shift) in the tire circumferential direction, and the first block 31B and the second block 32B adjacent to each other across the second circumferential narrow main groove 21B are also arranged with a 1 / 4 pitch (P / 4) shift in the tire circumferential direction. Note that the block pattern of the tread portion 20 is not limited to that shown in FIG. 2, and the circumferential length of the first block 31B and the second block 32B, the displacement amount of each block, etc. can be appropriately changed. Also, the direction in which the sipes 24 extend is not limited to the tire width direction as long as they intersect the circumferential narrow main groove 21, and all the sipes 24 may be configured to be inclined with respect to the tire width direction. For example, in the first land portion 31 and the second land portion 32 on both sides across the tire equatorial plane CL, they may be configured to be inclined with respect to the tire width direction such that the inclination directions of the sipes 24 are in a V-shaped pattern.

[0033] In this configuration, in the tread portion 20, the first circumferential narrow main groove 21A and the second circumferential narrow main groove 21B having a groove width W1 narrower than the groove width W4 of the circumferential main groove 22 partition the first land portion 31 and the second land portion 32. Therefore, when the tire 1 comes into contact with the ground, the first circumferential narrow main groove 21A and the second circumferential narrow main groove 21B close, and adjacent first blocks 31B or the first block 31B and the second block 32B act as wide blocks, thereby reducing the rolling resistance. Further, for adjacent first land portions 31 or adjacent first land portion 31 and second land portion 32, the first block 31B and the second block 32B are arranged with their positions shifted in the tire circumferential direction. Therefore, communication between the sipe 24 is prevented, and the noise when the tire 1 comes into contact with the ground can be reduced. Also, since the sipe 24 is formed such that the groove width W5 is smaller than the groove width W1 of the circumferential narrow main groove 21, it is possible to improve the traction performance while reducing the rolling resistance. Further, since the circumferential main groove 22 is the main groove located on the outermost side in the tire width direction, it has less influence on the rolling resistance than the circumferential narrow main groove 21 arranged on the central side. In this configuration, the groove width W4 of the circumferential main groove 22 is preferably 3.0% or more and 5.0% or less of the ground contact width TW of the tread portion 20, and more preferably 3.5% or more and 4.5% or less. By setting the groove width W4 of the circumferential main groove 22 to 3.0% or more and 5.0% or less of the ground contact width TW of the tread portion 20, it is possible to improve the wet traction performance without deteriorating the rolling resistance.

[0034] In the tread portion 20, the ratio (TWc / TW) of the width (length) TWc in the tire width direction of the land portion partitioned by the pair of circumferential main grooves 22, 22 to the ground contact width TW of the tread portion 20 is preferably in the range of 0.50 or more and 0.60 or less. Thereby, since it is possible to form a tread pattern in which block rows are concentratedly arranged in the center portion of the tread portion 20, the rigidity of the tread portion 20 can be increased, and the effect of reducing the rolling resistance can be improved.

[0035] Here, the width TWc is the length in the tire width direction between the pair of circumferential main grooves 22, 22, and is the sum of the widths of the four block rows (the first land part 31 and the second land part 32) and the groove width W1 of the three circumferential narrow main grooves 21. In other words, the width TWc refers to the straight-line distance in the tire width direction between the pair of circumferential main grooves 22, 22 in the developed view of the tread part 20 of the tire 1 when the tire 1 is mounted on the specified rim and filled with the specified internal pressure without applying a load. The ground contact width TW of the tread part 20 is the distance in the tire width direction between both ends on the outer sides in the tire width direction of the two shoulder land parts 33. This ground contact width TW is a length equivalent to the tread developed width, and the tread developed width refers to the straight-line distance between both ends in the developed view of the tread part 20 of the tire 1 when the tire 1 is mounted on the specified rim and filled with the specified internal pressure without applying a load. Also, the specified rim refers to the "Applicable Rim" specified by JATMA, the "Design Rim" specified by TRA, or the "Measuring Rim" specified by ETRTO. Also, the specified internal pressure refers to the "Maximum Air Pressure" specified by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "INFLATION PRESSURES" specified by ETRTO. Also, the specified load refers to the "Maximum Load Capacity" specified by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO.

[0036] Incidentally, in this configuration, in order to reduce the rolling resistance of the tire 1 as described above, the tread portion 20 has the first circumferential narrow main grooves 21A and the second circumferential narrow main grooves 21B having a groove width W1 narrower than the groove width W4 of the circumferential main grooves 22, and the first land portions 31 and the second land portions 32 partitioned thereby are concentrated and arranged in the center portion. On the other hand, in the above-described configuration, there is a concern that the wet traction performance of the original block pattern may be deteriorated because the groove volume of the circumferential narrow main grooves 21 is reduced and the drainage performance is deteriorated. For this reason, as shown in FIG. 3, the circumferential narrow main grooves 21 have a stepped groove shape including a narrow groove portion (opening portion) 211 and a widened portion 212 having a groove width wider than that of the narrow groove portion 211 on the groove bottom side (inner side in the tire diameter direction) than the narrow groove portion 211. In the present embodiment, all three circumferential narrow main grooves 21 are configured to include the widened portions 212, but at least one circumferential narrow main groove 21 may include the widened portion 212. In this case, it is preferable that one circumferential narrow main groove 21 including the widened portion 212 is provided at the position of the tire equatorial plane CL (center in the tire width direction) or in the vicinity of the position of the tire equatorial plane CL.

[0037] The narrow groove portion 211 of the circumferential narrow main groove 21 opens to the tread surface 200 of the tread portion 20 and is a portion in a region less than 30% (0.3H1) of the maximum groove depth H1 from the tread surface 200. This maximum groove depth H1 refers to the groove depth of the circumferential narrow main groove 21 when the tire is new. The groove width W1 of the narrow groove portion 211 is preferably larger than 1.0 mm and 4.0 mm or less. When the groove width W1 is 1.0 mm or less, the drainage performance deteriorates, so the wet traction performance deteriorates. On the other hand, when the groove width W1 is larger than 4.0 mm, the rigidity of the block rows adjacent to each other across the circumferential narrow main groove 21 decreases, so the rolling resistance deteriorates. In this configuration, by setting the groove width W1 of the narrow groove portion 211 to be larger than 1.0 mm and 4.0 mm or less, when the tire 1 comes into contact with the ground, the circumferential narrow main groove 21 closes and the groove walls support each other, so that the block rigidity is improved, the energy loss at the groove bottom is reduced, and the rolling resistance can be reduced. The groove width W1 of the narrow groove portion 211 is more preferably 1.5 mm or more and 3.0 mm or less.

[0038] The widening portion 212 has a widening start point (widening start position) 212A that is continuous with the narrow groove portion 211 on the outer side in the tire diameter direction, and is a portion in a region of 30% or more from the tread surface 200 of the tread portion 20 with the maximum groove depth H1. The widening portion 212 has a maximum groove width W2 that is wider than the groove width W1 of the narrow groove portion 211. The widening start point 212A refers to a height position at which the groove width is widened to a predetermined value (for example, the smaller of 1.2 times the groove width W1 of the narrow groove portion 211 or the groove width W1 + 0.5 mm). In this configuration, since the circumferential narrow main groove 21 includes a widening portion 212 that is wider than the narrow groove portion 211 in a region of 30% or more from the tread surface 200 of the tread portion 20 with the maximum groove depth H1, water enters the widening portion 212, thereby improving the drainage performance and improving the wet traction performance.

[0039] Specifically, it is preferable that the maximum groove width W2 of the widening portion 212 is 3.0 mm or more and 8.0 mm or less, and the ratio (W2 / W1) of the groove width W1 of the narrow groove portion 211 described above to the maximum groove width W2 of the widening portion 212 is preferably within the range of 1.0 < (W2 / W1) ≤ 4.0. When this ratio (W2 / W1) is 1.0 or less, the wet traction performance deteriorates. On the other hand, when the ratio (W2 / W1) is greater than 4.0, the rigidity of the block rows adjacent to each other across the circumferential narrow main groove 21 decreases, so the rolling resistance deteriorates. Also, when the ratio (W2 / W1) is greater than 4.0, the degree of widening of the maximum groove width W2 of the widening portion 212 with respect to the groove width W1 of the narrow groove portion 211 becomes excessively large, so there is also a problem that the processing of the circumferential narrow main groove 21 is difficult and the productivity deteriorates. By setting the ratio (W2 / W1) of the groove width W1 of the narrow groove portion 211 to the maximum groove width W2 of the widening portion 212 within the range of 1.0 < (W2 / W1) ≤ 4.0, it is possible to achieve both a reduction in rolling resistance and an improvement in wet traction performance. Further, it is more preferable that the ratio (W2 / W1) is 1.5 ≤ (W2 / W1) ≤ 3.0.

[0040] In the above-described tire 1, the circumferential narrow main groove 21 having the widened portion 212 is provided with a plurality of notches 213 that bulge toward one side (one side) in the tire width direction at intervals in the tire circumferential direction as shown in FIG. 2, and sipe 24 is connected (communicated) to each of these notches 213. These notches 213 are voids corresponding to reinforcing portions that reinforce the connection portion between the circumferential narrow main groove and the sipe in a mold (not shown) for molding the tire 1. Therefore, in this configuration, the notch 213 is formed to bulge toward the side connected to the sipe 24. In the example of FIG. 2, although the sipe 24 is connected to all the notches 213, in the circumferential narrow main groove 21, it is sufficient that the sipe 24 is connected to at least one notch 213, and among the plurality of notches 213, there may be a notch 213 that is not connected to the sipe 24.

[0041] Further, as shown in FIG. 3, the notch 213 extends in the tire radial direction from the tread surface 200 of the tread portion 20 to the widened portion 212 and communicates with the widened portion 212. As a result, the groove width (opening area) of the narrow groove portion 211 of the circumferential narrow main groove 21 increases by the amount of the notch 213, so the drainage performance of the circumferential narrow main groove 21 is improved and the wet traction performance is improved. On the other hand, by providing the notch 213, the rigidity of the block rows adjacent to each other across the circumferential narrow main groove 21 decreases by the amount of the notch 213, so there is a concern about deterioration of the rolling resistance.

[0042] Therefore, in this configuration, as shown in FIG. 2, the notch 213 is formed to bulge in a substantially semi-circular shape only on one side in the tire width direction of the circumferential narrow main groove 21, that is, on the side connected to each sipe 24. For this reason, compared with the configuration in which notches bulge on both sides in the tire width direction across the circumferential narrow main groove, the groove wall of the circumferential narrow main groove 21 on the side where the notch 213 does not bulge is formed flat, and this flat groove wall supports the groove wall bulged by the notch 213, so that a decrease in block rigidity can be suppressed and a reduction in rolling resistance can be achieved.

[0043] In addition, in this configuration, the notch portion 213 is such that the opening area on the tread surface 200 of the tread portion 20 is 1.5 mm 2 or more and 10.0 mm 2 or less. This opening area is determined as the area of the region A surrounded by the virtual line VL1 obtained by extending the groove wall 211A of the narrow groove portion 211 provided with the notch portion 213 and the contour line 213A of the notch portion 213 and the virtual line VL2 obtained by extending the contour line 213A, as shown in FIG. 4, when the tire 1 is rim-mounted on the above-described specified rim and filled with 100 kPa. If the opening area is less than 1.5 mm 2 , the wet traction performance cannot be sufficiently improved. Also, when the opening area is larger than 10.0 mm 2 , the rigidity of the block row decreases and the rolling resistance deteriorates. In this configuration, by setting the opening area of the notch portion 213 on the tread surface 200 of the tread portion 20 to be 1.5 mm 2 or more and 10.0 mm 2 or less, it is possible to achieve both an improvement in wet traction performance and a suppression of deterioration of rolling resistance. Also, the above-described opening area of the notch portion 213 is more preferably 1.5 mm 2 or more and 8.0 mm 2 or less.

[0044] In addition, the ratio (Wa / W1) of the width Wa of the notch portion 213 to the groove width W1 of the narrow groove portion 211 is preferably in the range of 0.5 ≤ (Wa / W1) ≤ 2.0. The width Wa of this notch portion 213 can be determined as the maximum distance between the virtual line VL1 and the virtual line VL2 shown in FIG. 4 under the conditions for obtaining the above-described opening area. If this ratio (Wa / W1) is less than 0.5, the width Wa of the notch portion 213 is small with respect to the groove width W1 of the narrow groove portion 211, and the wet traction performance cannot be sufficiently improved. Also, when the ratio (Wa / W1) is larger than 2.0, the rigidity of the block row decreases and the rolling resistance deteriorates. In this configuration, by setting the ratio (Wa / W1) of the width Wa of the notch portion 213 to the groove width W1 of the narrow groove portion 211 to be in the range of 0.5 ≤ (Wa / W1) ≤ 2.0, it is possible to achieve both an improvement in wet traction performance and a suppression of deterioration of rolling resistance.

[0045] In addition, as described above, in the circumferential-direction main narrow groove 21, the ratio (W2 / W1) of the groove width W1 of the narrow groove portion 211 to the maximum groove width W2 of the widened portion 212 is in the range of 1.0 < (W2 / W1) ≤ 4.0. In addition to this, it is preferable that the ratio (Wa / Wb) of the width Wa of the notch portion 213 to the width Wb from the narrow groove portion 211 to the widened portion 212 is in the range of 0.5 ≤ (Wa / Wb) ≤ 2.0. Here, the width Wb is the maximum distance between the narrow groove portion 211 and the widened portion 212 in the tire width direction, and can be obtained as the maximum distance in the tire width direction between the virtual line VL3 obtained by extending the groove wall 211A of the narrow groove portion 211 in the tire diameter direction and the contour line 212B of the widened portion 212 under the conditions for obtaining the above-described opening area. When this ratio (Wa / Wb) is less than 0.5, the width Wa of the notch portion 213 with respect to the width Wb is small, and sufficient drainage to the widened portion 212 through the notch portion 213 cannot be achieved, and the wet traction performance cannot be sufficiently improved. Further, when the ratio (Wa / Wb) is greater than 2.0, the rigidity of the block row decreases and the rolling resistance deteriorates. In this configuration, since the ratio (W2 / W1) of the groove width W1 of the narrow groove portion 211 to the maximum groove width W2 of the widened portion 212 is in the range of 1.0 < (W2 / W1) ≤ 4.0, and the ratio (Wa / Wb) of the width Wb from the narrow groove portion 211 to the widened portion 212 to the width Wa of the notch portion 213 is in the range of 0.5 ≤ (Wa / Wb) ≤ 2.0, appropriate dimensional conditions of the circumferential-direction main narrow groove 21 can be defined, and both improvement of wet traction performance and suppression of deterioration of rolling resistance can be achieved.

[0046] In the above-described tire 1, as shown in FIG. 5, the maximum groove depth H1 of the circumferential narrow main groove 21 is formed to be equal to the groove depth H4 of the circumferential main groove 22. Specifically, the ratio (H1 / H4) of the maximum groove depth H1 to the groove depth H4 is in the range of 0.95 ≦ (H1 / H4) ≦ 1.05. Therefore, the circumferential narrow main groove 21 can improve the wet traction performance by ensuring drainage together with the circumferential main groove 22 even at the end of wear. Further, it is preferable that the groove depth H5 of the sipe 24 satisfies the relationship of H3 < H5 < 0.9H1 with respect to the depth H3 from the tread surface 200 of the tread portion 20 to the connection portion 213B between the notch portion 213 and the widened portion 212 and the maximum groove depth H1 of the circumferential narrow main groove 21.

[0047] This connection portion 213B is located at the innermost position in the tire radial direction at the connection portion between the notch portion 213 and the widened portion 212, and is the intersection of the virtual line VL4 extending in the tire radial direction from the measurement point of the width Wa of the notch portion 213 and the contour line 212B of the widened portion 212. Since the groove depth H5 of the sipe 24 is made larger than the depth H3 from the tread surface 200 of the tread portion 20 to the connection portion 213B of the notch portion 213, the sipe 24 can be directly connected to the widened portion 212 of the circumferential narrow main groove 21, improving drainage and thus improving wet traction performance.

[0048] Furthermore, as shown in FIG. 6, the sipe 24 preferably includes a widened sipe (widened portion) 241 with a widened groove width at the bottom. By providing the widened sipe 241 at the bottom of the sipe 24, the drainage of the sipe 24 can be improved, thereby improving the wet traction performance. Also, the widened sipe 241 has a maximum width W6 and a height H6 from the groove bottom, and it is preferable that these maximum width W6 and height H6 are each 1.2 times or more and 3.0 times or less the groove width W5 of the sipe 24. In this case, if it is less than 1.2 times, the wet traction performance cannot be sufficiently improved. Also, if it is larger than 3.0 times, the widened sipe 241 becomes relatively large, reducing the rigidity of the block row adjacent in the tire circumferential direction and deteriorating the rolling resistance.

[0049] In the above-described tire 1, the number of notches 213 provided in one circumferential narrow main groove 21 is preferably 10 or more and 20 or less within the contact surface of the tread portion 20. The contact surface refers to the region where the tire 1 and the flat plate are in contact when the tire 1 is mounted on a specified rim, filled with a specified internal pressure, placed perpendicular to the flat plate in a stationary state, and a load corresponding to a specified load is applied. When the number of notches 213 within the contact surface is less than 10, sufficient drainage cannot be achieved through the notches 213 to the widened portion 212, and the wet traction performance cannot be sufficiently improved. Further, when the number of notches 213 within the contact surface is more than 20, the rigidity of the block row decreases and the rolling resistance deteriorates. In this configuration, by setting the number of notches 213 within the contact surface to be 10 or more and 20 or less, it is possible to define a numerical range in which the wet traction performance can be improved without the rolling resistance deteriorating. Moreover, it is more preferable that the number of notches 213 within the contact surface is 12 or more and 15 or less.

[0050] Further, in the above-described tire 1, among the plurality of notches 213 provided in one circumferential narrow main groove 21, the ratio (Nin / Nout) of the number Nin of the notches 213 bulging inward in the tire width direction to the number Nout of the notches 213 bulging outward in the tire width direction of the circumferential narrow main groove 21 is preferably 0.2 ≦ (Nin / Nout) ≦ 1.0. This regulation indicates that more notches 213 are formed on the shoulder side than on the tire equatorial plane CL side. Also, in the example of FIG. 2, since the first circumferential narrow main groove 21A is provided at the position of the tire equatorial plane CL, for the notches 213 provided in the first circumferential narrow main groove 21A, when one side in the tire width direction is taken as the outside, the other side is taken as the inside, and the ratio (Nin / Nout) is set to 1.0.

[0051] When the above ratio (Nin / Nout) is less than 0.2, the notches 213 concentrate on the outer side in the tire width direction, resulting in a decrease in the block rigidity on the outer side in the tire width direction and a deterioration of the rolling resistance. Also, when the ratio (Nin / Nout) is greater than 1.0, the number of notches 213 on the tire equatorial plane CL side becomes larger than that on the shoulder side, which may deteriorate the drainage performance. In this configuration, by setting the ratio (Nin / Nout) within the range of 0.2 ≤ (Nin / Nout) ≤ 1.0, it is possible to suppress the deterioration of the rolling resistance while maintaining the drainage performance. It is more preferable that this ratio (Nin / Nout) is set to 0.2 ≤ (Nin / Nout) ≤ 1.0.

[0052] Also, in the above-described tire 1, the ratio (N2 / N1) of the number N1 of the first land portions 31 partitioned by the sipes 24 and arranged in the tire circumferential direction and the number N2 of the second land portions 32 partitioned by the sipes 24 and arranged in the tire circumferential direction preferably satisfies the range of 1.2 ≤ (N2 / N1) ≤ 2.0. That is, it is preferable that the number N2 of the second blocks 32B located on the outer side in the tire width direction is formed more than the number N1 of the first blocks 31B within the above-described range. When the ratio (N2 / N1) is less than 1.2, the drainage from the first land portion 31 to the second land portion 32 is suppressed through each sipe 24, so the wet traction performance deteriorates. Also, when the ratio (N2 / N1) is greater than 2.0, the block rigidity of the second land portion 32 decreases, so the rolling resistance deteriorates. In this configuration, by setting the ratio (N2 / N1) within the range of 1.2 ≤ (N2 / N1) ≤ 2.0, it is possible to ensure the block rigidity of the first land portion 31 and the second land portion 32 with high ground pressure, and to ensure the number of sipes 24 connected to the circumferential main groove 22 with higher drainage performance. Therefore, it is possible to achieve both an improvement in wet traction performance and a reduction in rolling resistance.

[0053] Next, another embodiment will be described. FIG. 7 is a developed view showing a tread pattern of a pneumatic tire according to another embodiment. FIG. 8 is an enlarged view of the tread portion shown in FIG. 7. In the above-described embodiment, the circumferential narrow main groove 21 and the circumferential main groove 22 provided in the tread portion 20A were each straight, whereas in this another embodiment, the circumferential narrow main groove 21 and the circumferential main groove 22 are each zigzag-shaped, extending in the tire circumferential direction and repeatedly bending alternately in the tire width direction, which makes a great difference in the configuration. In the present embodiment, the configuration different from the above-described embodiment will be described, and the description of the same configuration as the above-described embodiment, such as the circumferential narrow main groove 21 being a stepped groove having a narrow groove portion 211 and a widened portion 212, will be omitted.

[0054] As shown in FIG. 7, the circumferential narrow main groove 21 and the circumferential main groove 22 each have a long portion and a short portion (reference numerals in the figure are omitted), and have a zigzag shape formed by connecting these long portions and short portions alternately. In the example of FIG. 7, the long portions of the circumferential main groove 22 are inclined in the same direction (diagonal downward direction in the figure) with respect to each other. Further, the long portions of the first circumferential narrow main groove 21A and the second circumferential narrow main groove 21B are inclined in opposite directions (diagonal downward direction in the figure) in the tire circumferential direction with respect to the long portions of the circumferential main groove 22. According to this configuration, since the circumferential narrow main groove 21 and the circumferential main groove 22 arranged in the center region of the tread portion with high ground pressure are formed in a zigzag shape, the edge components of the circumferential narrow main groove 21 and the circumferential main groove 22 increase and the traction performance is improved.

[0055] As shown in FIG. 7, the tread portion 20A includes a first land portion 31 partitioned by adjacent first circumferential narrow main grooves 21A and second circumferential narrow main grooves 21B, and a second land portion 32 partitioned by adjacent second circumferential narrow main grooves 21B and circumferential main grooves 22. The first land portion 31 and the second land portion 32 are each partitioned into a plurality of first blocks 31B and second blocks 32B by a plurality of sipes 24 extending in the tire width direction.

[0056] Also in the present embodiment, the tread portion 20A is configured to partition the first land portion 31 and the second land portion 32 by the first circumferential narrow main groove 21A and the second circumferential narrow main groove 21B having a groove width W1 narrower than the groove width W4 of the circumferential main groove 22, and a tread pattern in which block rows are intensively arranged is formed at the center portion of the tread portion 20A.

[0057] Here, the elongated portion of the first circumferential narrow main groove 21A on the tire equatorial plane CL has a linear shape. Thereby, the wet traction performance of the tire can be maintained. Further, the elongated portions of the second circumferential narrow main groove 21B each have an arc shape that protrudes toward the tire equatorial plane CL side. For this reason, the deformation of the first block 31B during tire rolling is suppressed, and the rolling resistance of the tire 1 can be reduced.

[0058] Also, as shown in FIG. 8, the first circumferential narrow main groove 21A and the second circumferential narrow main groove 21B are formed such that the zigzag pitch length P2 and the circumferential length L2 of the elongated portion are substantially the same, and the ratio (L2 / P2) of the circumferential length L2 of the elongated portion to the zigzag pitch length P2 is in the range of 0.85 ≦ L2 / P2 ≦ 1.00, preferably in the range of 0.90 ≦ L2 / P2 ≦ 0.96. Thereby, the zigzag shape of the first circumferential narrow main groove 21A and the second circumferential narrow main groove 21B is optimized. In particular, due to the lower limit value of the specified range, the collapse of the blocks is effectively suppressed, and the edge component increases to reduce the rolling resistance of the tire 1.

[0059] In addition, the intersection point 214 where the long portion and the short portion in the first circumferential direction fine main groove 21A and the second circumferential direction fine main groove 21B are connected becomes the maximum amplitude position in the zigzag-shaped first circumferential direction fine main groove 21A and the second circumferential direction fine main groove 21B. In this configuration, the intersection point 214 protruding outward in the tire width direction (shoulder side) of the first circumferential direction fine main groove 21A and the intersection point 214 protruding inward in the tire width direction (tire equatorial plane CL side) of the second circumferential direction fine main groove 21B are connected by the first siped 24A. These first sipes 24A have a straight shape or a gentle arc shape. In this way, since the intersection points 214 of the zigzag-shaped first circumferential direction fine main groove 21A and the second circumferential direction fine main groove 21B are connected, the drainage performance is improved. Further, the intersection point 214 protruding outward in the tire width direction of the second circumferential direction fine main groove 21B and the circumferential direction main groove 22 are connected by the first siped 24A. In this case, the first siped 24A has a straight or gentle arc shape and extends along the extension line of the center line of the short portion of the second circumferential direction fine main groove 21B and is connected to the circumferential direction main groove 22.

[0060] In addition, the first circumferential direction fine main groove 21A and the adjacent second circumferential direction fine main groove 21B are each connected by one second siped 24B. This second siped 24B has a gentle S shape and connects the intermediate portions in the tire circumferential direction of the respective long portions of the first circumferential direction fine main groove 21A and the second circumferential direction fine main groove 21B. Thereby, the drainage performance of the first land portion 31 (ground contact area) partitioned by the long portions of the zigzag shape is improved. Here, the connection positions of the second sipes 24B to the long portions of the first circumferential direction fine main groove 21A are set to different (displaced) positions in the tire circumferential direction. Thereby, it is possible to prevent the second sipes 24B connected to the long portions of the first circumferential direction fine main groove 21A from being directly connected. Further, the second circumferential direction fine main groove 21B and the circumferential direction main groove 22 are each connected by at least one (two in the example of FIG. 8) second siped 24B. In this case, the two second sipes 24B extending outward in the tire width direction from the second circumferential direction fine main groove 21B are connected at positions sandwiching the second siped 24B connected to the first circumferential direction fine main groove 21A. Thereby, it is possible to improve the drainage performance from the tire equatorial plane CL side to the outside in the tire width direction.

[0061] In the tread portion 20A having the above-described configuration, the first circumferential-direction narrow main groove 21A and the second circumferential-direction narrow main groove 21B each include a plurality of notch portions 213 formed at intervals in the tire circumferential direction in the long portion, and sipe 24 (first sipe 24A and second sipe 24B) is connected to each of these notch portions 213. Specifically, notch portions 213 are provided so as to bulge on the convex side of both ends of the long portion, that is, the intersection 214 of the long portion and the short portion, and the first sipe 24A is connected to this notch portion 213. Here, the convex side of the intersection 214 of the long portion and the short portion means the side with the larger angle among the two angles formed by the long portion and the short portion.

[0062] Also, on one long portion located between these intersections 214, one or more notch portions 213 that bulge independently on the outer side and the inner side in the tire width direction are provided respectively, and the second sipe 24B having a gentle S shape is connected to each of these notch portions 213. In the example of FIG. 8, on the long portion of the second circumferential-direction narrow main groove 21B, two notch portions 213 are provided on the outer side in the tire width direction of the long portion, and one notch portion 213 is provided on the inner side in the tire width direction. Here, "bulging independently" means that each notch portion 213 exists individually without overlapping in the tire circumferential direction. Also, in the example of FIG. 8, since the first circumferential-direction narrow main groove 21A is provided at the position of the tire equatorial plane CL, for the notch portions 213 provided in the first circumferential-direction narrow main groove 21A, when one side in the tire width direction is taken as the outer side, the other side is taken as the inner side, and they bulge independently one by one.

[0063] Also in this embodiment, as shown in FIG. 8, the notch portion 213 bulges and is formed only on one side in the tire width direction of the circumferential-direction narrow main groove 21, that is, the side connected to each sipe 24. For this reason, compared with a configuration in which notch portions bulge on both sides in the tire width direction with the circumferential-direction narrow main groove interposed therebetween, the groove wall of the circumferential-direction narrow main groove 21 on the side where the notch portion 213 does not bulge supports the groove wall bulged by the notch portion 213, so that a decrease in block rigidity can be suppressed and rolling resistance can be reduced.

[0064] Also, when the maximum length in the tire circumferential direction on the ground contact surface of the tread portion 20A is defined as the ground contact length L1 (not shown), the ratio (L1 / P2) of this ground contact length L1 to the pitch length P2 of the zigzag shape described above is within the range of 2.5 ≤ (L1 / P2) ≤ 4.0. The ground contact surface refers to the region where the tire 1 and the flat plate are in contact when the tire 1 is mounted on a specified rim, filled with a specified internal pressure, and placed perpendicular to the flat plate in a stationary state and a load corresponding to a specified load is applied. In the present embodiment, since at least five notches 213 are provided in the pitch length P2 of the zigzag shape, by setting the ground contact length L1 and the pitch length P2 of the zigzag shape described above within the range of 2.5 ≤ (L1 / P2) ≤ 4.0, the number of notches 213 in the ground contact surface in one circumferential-direction narrow main groove 21 can be set to be 10 or more and 20 or less. Therefore, it is possible to define a numerical range in which the wet traction performance can be improved without deteriorating the rolling resistance.

[0065] In the present embodiment, the zigzag shape is described as being formed by alternately connecting long portions and short portions. However, the present invention is not limited to this, and a zigzag shape may be formed by alternately connecting portions set to have the same length. Further, in the present embodiment, the notch 213 is provided at the intersection 214 of the long portion and the short portion. However, it goes without saying that the notch 213 may be provided in a long portion close to the intersection 214.

Example

[0066] FIG. 9 is a table showing the results of the performance test of the pneumatic tire according to the present embodiment. In this performance test, a plurality of types of test tires were evaluated for their rolling resistance performance and wet traction performance. The size of the pneumatic tire 1 used for the evaluation is 275 / 80R22.5. The vehicle used for the evaluation is a vehicle in which a trailer is connected to a 6×4 tractor.

[0067] For the evaluation of rolling resistance performance, an indoor drum tester was used. In the evaluation of rolling resistance performance, the test tire was filled with the specified internal pressure, and the resistance at a load of 31.26 kN and a speed of 80 km / h was measured. Based on this measurement result, an index evaluation was performed with the tire of the conventional example as the reference (100). This evaluation indicates that the larger the index, the smaller the rolling resistance and the better the rolling resistance performance.

[0068] Regarding the evaluation of wet traction performance, the test tire was mounted on the rim with an air pressure of 900 kPa and mounted on the drive shaft of the tractor head to evaluate the wet braking performance. In the evaluation of wet braking performance, on the test course, the deceleration G was measured when the evaluation vehicle equipped with the test tire decelerated from an initial speed of 60 km / h to 20 km / h on a road surface sprinkled with water to a water depth of about 1 mm. Based on this measured deceleration G, an index evaluation was performed with the tire of the conventional example as the reference (100). This evaluation indicates that the larger the numerical value, the shorter the braking distance and the better the wet braking performance, that is, the wet traction performance.

[0069] As shown in Fig. 9, the test tires of the conventional example and Examples 1 to 15 differ in the shape of the circumferential narrow main groove, the presence or absence of a notch bulging out on one side across the circumferential narrow main groove, the opening area of the notch, the ratio (Wa / W1) of the width Wa of the notch to the groove width W1 of the circumferential narrow main groove, the number of notches provided in the circumferential narrow main groove within the ground contact surface of the tread portion, the ratio of the number of notches on the outer side and the inner side in the tire width direction in one circumferential narrow main groove, etc. Note that the test tire of the conventional example has a straight-shaped circumferential narrow main groove with a widened portion, but the notch at the portion connecting the circumferential narrow main groove and the sipe bulges out on both sides across the circumferential narrow main groove.

[0070] As a result of performing a performance evaluation test using these test tires, as shown in Fig. 9, the test tires of Examples 1 to 15 were able to achieve a reduction in rolling resistance and an improvement in wet braking performance in comparison with the conventional example. In particular, a significant improvement in wet braking performance was achieved.

[0071] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, in this embodiment, a pneumatic tire has been exemplified and described as the tire, but the present invention is not limited thereto, and it goes without saying that the present invention can also be applied to a tire not filled with air such as a non-pneumatic tire. Further, as the gas filled in the pneumatic tire exemplified in this embodiment, in addition to normal air or air with adjusted oxygen partial pressure, inert gases such as nitrogen, argon, and helium can be used.

Explanation of reference numerals

[0072] 1 Pneumatic tire 20, 20A Tread portion 21 Circumferential narrow main groove 21A First circumferential narrow main groove 21B Second circumferential narrow main groove 22 Circumferential main groove 24 Sipe 24A First sipe 24B Second sipe 31 First land portion 31B First block 32 Second land portion 32B Second block 33 Shoulder land portion 200 Tread surface 211 Narrow groove portion (opening) 212 Widening portion 213 Notch portion 214 Intersection point 241 Widening sipe

Claims

1. The groove width of the opening that opens on the surface of the tread portion is more than 1.0 mm and 4.0 mm or less, and one or more circumferential grooves extending in the tire circumferential direction, and when the tire is new, the groove width that opens on the surface of the tread portion is 1.0 mm or less, and a plurality of widthwise sipes communicating with the circumferential grooves, The number of the widthwise sipes communicating with one of the circumferential grooves from the outer side in the tire width direction is larger than the number of the widthwise sipes communicating with one of the circumferential grooves from the inner side in the tire width direction along the entire circumference of the tire, At least one of the circumferential grooves has a widened portion where the groove width widens more than the opening in a region where the groove depth from the surface of the tread portion is 30% or more of the maximum groove depth, and a plurality of them are provided at intervals in the tire circumferential direction, and a notch portion that bulges only on one side in the tire width direction and communicates from the surface of the tread portion to the widened portion, The widthwise sipes are connected to at least one of the notch portions, All of the circumferential grooves are in a zigzag shape that extends in the tire circumferential direction and repeatedly bends alternately in the tire width direction, and the circumferential grooves in the zigzag shape are formed by alternately connecting long portions and short portions. A tire characterized by this.

2. The notch has an opening area on the surface of the tread portion of 1.5 mm ２ or more and 10.0 mm ２ or less. The tire according to claim 1.

3. The tire according to claim 1 or 2, wherein the width Wa of the notch portion and the groove width W1 of the opening are in the range of 0.5 ≦ (Wa / W1) ≦ 2.

0.

4. The tire according to any one of claims 1 to 3, wherein the number of the notch portions provided in one of the circumferential grooves is 10 or more and 20 or less within the ground contact surface of the tread portion.

5. The tire according to any one of claims 1 to 4, wherein the ratio of the number of the notch portions bulging inward to the number of the notch portions bulging outward in the tire width direction of one of the circumferential grooves is 0.2 or more and 1.0 or less.

6. The maximum groove width W2 of the widened portion and the groove width W1 of the opening are in the range of 1.0 < (W2 / W1) ≦ 4.0, The tire according to any one of claims 1 to 5, wherein the width Wb from the opening to the widened portion and the width Wa of the notch portion are in the range of 0.5 ≦ (Wa / Wb) ≦ 2.

0.

7. In the tire according to any one of claims 1 to 6, the groove depth H5 of the width-direction sipe satisfies the relationship H3 < H5 < 0.9H1, where H3 is the depth from the surface of the tread portion in the circumferential-direction fine groove to the connection portion between the notch portion and the widened portion, and H1 is the maximum groove depth of the circumferential-direction fine groove.

8. In the tire according to any one of claims 1 to 7, the width-direction sipe includes a widened sipe widened at the bottom, and the maximum width and the height from the bottom surface of the widened sipe are 1.2 times or more and 3.0 times or less of the groove width on the surface of the tread portion.

9. The tread portion is provided with a pair of circumferential-direction main grooves disposed on the outer side in the tire width direction with the circumferential-direction fine groove therebetween and extending in the tire circumferential direction. The groove width W4 of the circumferential-direction main groove with respect to the contact width TW of the tread portion is in the range of 3.0% or more and 5.0% or less. In the tire according to any one of claims 1 to 8, the width TWc in the tire width direction of the land portion partitioned by the pair of circumferential-direction main grooves and the contact width TW satisfy the range 0.40 ≦ (TWc / TW) ≦ 0.

55.

10. In the tire according to any one of claims 1 to 9, at least one notch portion is provided on the convex side of the intersection of the long portion and the short portion.

11. In the tire according to any one of claims 1 to 10, one or more notch portions bulging outward and inward in the tire width direction are provided on one of the long portions.

12. In the tire according to any one of claims 1 to 11, for the zigzag-shaped circumferential-direction fine groove, the pitch length P2 of the circumferential-direction fine groove and the tire circumferential-direction length L2 of the long portion satisfy the range 0.85 ≦ (L2 / P2) ≦ 0.

92.

13. The tread portion is provided with a pair of circumferential-direction main grooves disposed on the outer side in the tire width direction with a plurality of the circumferential-direction fine grooves therebetween and extending in the tire circumferential direction. The tread portion includes a first land portion partitioned by a plurality of the circumferential-direction fine grooves between the pair of circumferential-direction main grooves, and a second land portion partitioned by the circumferential-direction fine grooves and the circumferential-direction main grooves. In the tire according to any one of claims 1 to 12, the number N1 of the first blocks arranged in the tire circumferential direction by partitioning the first land portion by the width-direction sipe and the number N2 of the second blocks arranged in the tire circumferential direction by partitioning the second land portion by the width-direction sipe satisfy the range 1.2 ≦ (N2 / N1) ≦ 2.0.

Images