tire

Abstract

Provided is a tire that can improve wear resistance while maintaining good rolling resistance and wet performance. [Solution] The present invention provides a tire 1 having a tread portion 2. The tread portion 2 has circumferential grooves 3 extending in the tire circumferential direction and land portions 4 separated by the circumferential grooves 3. The circumferential grooves 3 include narrow groove portions 3a with a narrow groove width on the radially outer side of the tire, and widened portions 3b with a wider groove width on the radially inner side of the narrow groove portions 3a. The land portions 4 include a first land portion 4A and a second land portion 4B located axially inward of the first land portion 4A. The first land portion 4A and the second land portion 4B each have a plurality of sipes 5 crossing the first land portion 4A and the second land portion 4B. The maximum circumferential pitch P2 between circumferentially adjacent sipes 5 in the second land portion 4B is smaller than the maximum circumferential pitch P1 between circumferentially adjacent sipes 5 in the first land portion 4A.

Description

[Technical Field]

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

[0002] Conventionally, tires having a tread portion that can achieve both rolling resistance performance and wet performance have been known. For example, Patent Document 1 below proposes a tire that is provided with sipes extending in the tire axial direction and widened groove portions that extend in the tire axial direction on the radially inner side of the sipes and have a width larger than that of the sipes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-071453 Summary of the Invention [Problem to be solved by the invention]

[0004] However, expectations for rolling resistance performance have been increasing year by year even for tires such as those disclosed in Patent Document 1, and there has also been a demand for improvements in wear resistance performance.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire that can improve wear resistance while maintaining good rolling resistance performance and wet performance. [Means for solving the problem]

[0006] The present invention is a tire having a tread portion, the tread portion having a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of land portions separated by the plurality of circumferential grooves, at least one of the plurality of circumferential grooves including a narrow groove portion having a small groove width on the radially outer side of the tire and a widened portion having a large groove width on the radially inner side of the tire than the narrow groove portion, the plurality of land portions including a first land portion located on the outermost side of the tire in the axial direction and a second land portion located on the inner side of the tire than the first land portion, the first land portion and the second land portion each having a plurality of sipes crossing the first land portion and the second land portion, and the maximum circumferential pitch between the circumferentially adjacent sipes of the second land portion is smaller than the maximum circumferential pitch between the circumferentially adjacent sipes of the first land portion. [Effects of the Invention]

[0007] By virtue of having the above-described configuration, the tire of the present invention can improve wear resistance while maintaining good rolling resistance and wet performance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a development view showing an embodiment of a tread portion of a tire of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. 10 is a development view showing a tread portion of another embodiment. [Figure 4] FIG. 10 is a cross-sectional view of a circumferential groove of a second embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a circumferential groove of a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a tread development view showing 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. A suitable example of the tire 1 is a pneumatic tire for heavy loads. The tire 1 is not limited to this embodiment, and can be applied to various types of tires 1, such as pneumatic tires and airless tires for passenger cars, and tires for industrial machinery.

[0010] The tread portion 2 of this embodiment has a plurality of circumferential grooves 3 extending in the tire circumferential direction and a plurality of land portions 4 separated by the plurality of circumferential grooves 3. Such a tread portion 2 can suppress deformation of the land portions 4 when the tire comes into contact with the ground, and is useful for improving the rolling resistance performance and wear resistance performance of the tire 1.

[0011] The plurality of circumferential grooves 3 in this embodiment include first circumferential grooves 3A located on the outer side in the tire axial direction and second circumferential grooves 3B located on the inner side in the tire axial direction than the first circumferential grooves 3A. The plurality of circumferential grooves 3 include, for example, a pair of first circumferential grooves 3A and a pair of second circumferential grooves 3B on either side of the tire equator C.

[0012] Here, the "tire equator C" refers to the axially central position between a pair of tread edges Te on the contact surface 2a. In the case where the tire 1 is a heavy-duty pneumatic tire, the "tread edge Te" refers to the axially outermost contact point when the tire 1 is in a normal state and is subjected to a normal load, and the tire is in contact with a flat surface with a camber angle of 0°.

[0013] 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.

[0014] A "genuine rim" is a rim that is defined for each tire by a standard system that includes the standard on which tire 1 is based, such as a "standard rim" 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 such rims.

[0015] "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.

[0016] "Normal load" is the load specified for each tire by a standard system that includes the standard on which tire 1 is based, if such a system exists; 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 specified for each tire by the manufacturer, etc., as the maximum load that can be applied when using tire 1.

[0017] Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. As shown in Fig. 2, at least one of the plurality of circumferential grooves 3 of this embodiment includes a narrow groove portion 3a having a narrow groove width on the outer side in the tire radial direction, and a widened portion 3b having a wide groove width on the inner side in the tire radial direction than the narrow groove portion 3a.

[0018] Such circumferential grooves 3 allow the land portions 4 adjacent to the narrow groove portions 3a to come into contact with each other under load, thereby suppressing deformation of the land portions 4 when the tire comes into contact with the ground, thereby improving the rolling resistance and wear resistance of the tire 1. In addition, the widened portions 3b widen the groove width in the later stages of wear, thereby suppressing a decrease in drainage performance in the later stages of wear and helping to improve the wet performance of the tire 1.

[0019] 2 illustrates an example in which each of the first circumferential groove 3A and the second circumferential groove 3B includes a narrow groove portion 3a and a widened portion 3b, but is not limited to this example, and for example, only the second circumferential groove 3B may include a narrow groove portion 3a and a widened portion 3b. In this case, the first circumferential groove 3A may open to the contact patch 2a at the maximum groove width wg2 of the widened portion 3b.

[0020] 1, the land portions 4 of this embodiment include a first land portion 4A located at the outermost side in the tire axial direction and a second land portion 4B located axially more inward than the first land portion 4A. The land portions 4 also include, for example, a third land portion 4C located axially more inward than the second land portion 4B.

[0021] In this embodiment, the first land portion 4A is defined between the tread edge Te and the first circumferential groove 3A. The second land portion 4B is preferably defined between the first circumferential groove 3A and the second circumferential groove 3B. The third land portion 4C is defined, for example, between a pair of second circumferential grooves 3B and is located on the tire equator C.

[0022] 1 illustrates four circumferential grooves 3 and five land portions 4, but the tread portion 2 is not limited to this. The tread portion 2 may have, for example, two circumferential grooves 3 and three land portions 4, three circumferential grooves 3 and four land portions 4, or five or more circumferential grooves 3 and six or more land portions 4.

[0023] In this embodiment, the first land portion 4A, the second land portion 4B, and the third land portion 4C each have a plurality of sipes 5 that cross the first land portion 4A, the second land portion 4B, and the third land portion 4C, respectively. Such sipes 5 can drain water via the circumferential grooves 3, improving the wet performance of the tire 1. Here, the sipes 5 are cuts with a width of less than 1.0 mm in a direction perpendicular to the sipe longitudinal direction, and are clearly distinguished from grooves with a groove width of 1.0 mm or more.

[0024] The maximum circumferential pitch P2 between circumferentially adjacent sipes 5 of the second land portion 4B is preferably smaller than the maximum circumferential pitch P1 between circumferentially adjacent sipes 5 of the first land portion 4A.

[0025] In such land portion 4, the density of the sipes 5 in the second land portion 4B, which has a high ground contact pressure, is high, so that water can be drained more effectively, thereby improving the wet performance of the tire 1. Furthermore, the density of the sipes 5 in the first land portion 4A is low, so that high rigidity can be maintained, thereby improving the wear resistance of the tire 1. Therefore, the tire 1 of this embodiment can improve the wear resistance while maintaining good rolling resistance performance and wet performance.

[0026] In a more preferred embodiment, the maximum pitch P3 in the tire circumferential direction between circumferentially adjacent sipes 5 of the third land portion 4C is equal to the maximum pitch P2 of the second land portion 4B. In this case, the third land portion 4C may be included in the second land portion 4B without being distinguished from the second land portion 4B. Such a land portion 4 can maintain the high rigidity of the third land portion 4C and can further improve the wear resistance of the tire 1.

[0027] The maximum pitch P3 of the third land portion 4C may be smaller than the maximum pitch P2 of the second land portion 4B, for example. Such a land portion 4 can improve the drainage of the third land portion 4C, which has the highest ground contact pressure, and can further improve the wet performance of the tire 1.

[0028] The maximum width W1 of the first land portion 4A in the tire axial direction is preferably 1.0 times or more the maximum pitch P1 of the first land portion 4A. By making the maximum width W1 of the first land portion 4A 1.0 times or more the maximum pitch P1 of the first land portion 4A, the density of the sipes 5 of the first land portion 4A can be increased, and the wet performance of the tire 1 can be improved. From this perspective, the maximum width W1 of the first land portion 4A is more preferably 1.5 times or more the maximum pitch P1 of the first land portion 4A.

[0029] The maximum width W1 of the first land portion 4A is preferably 3.0 times or less the maximum pitch P1 of the first land portion 4A. By making the maximum width W1 of the first land portion 4A 3.0 times or less the maximum pitch P1 of the first land portion 4A, the rigidity of the first land portion 4A can be increased, and the wear resistance of the tire 1 can be improved. From this perspective, the maximum width W1 of the first land portion 4A is more preferably 2.5 times or less the maximum pitch P1 of the first land portion 4A.

[0030] For these reasons, the maximum width W1 of the first land portions 4A is preferably 1.0 to 3.0 times, and more preferably 1.5 to 2.5 times, the maximum pitch P1 of the first land portions 4A. The combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.

[0031] The maximum width W2 of the second land portion 4B in the tire axial direction is preferably 1.4 times or more the maximum pitch P2 of the second land portion 4B. By making the maximum width W2 of the second land portion 4B 1.4 times or more the maximum pitch P2 of the second land portion 4B, the density of the sipes 5 of the second land portion 4B can be increased, and the wet performance of the tire 1 can be improved. From this perspective, the maximum width W2 of the second land portion 4B is more preferably 1.5 times or more the maximum pitch P2 of the second land portion 4B.

[0032] The maximum width W2 of the second land portion 4B is preferably 3.0 times or less the maximum pitch P2 of the second land portion 4B. By making the maximum width W2 of the second land portion 4B 3.0 times or less the maximum pitch P2 of the second land portion 4B, the rigidity of the second land portion 4B can be increased, and the wear resistance of the tire 1 can be improved. From this perspective, the maximum width W2 of the second land portion 4B is more preferably 2.5 times or less the maximum pitch P2 of the second land portion 4B.

[0033] For these reasons, the maximum width W2 of the second land portions 4B is preferably 1.4 to 3.0 times the maximum pitch P2 of the second land portions 4B, and more preferably 1.5 to 2.5 times. The combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.

[0034] The maximum width W3 of the third land portion 4C in the tire axial direction is preferably 1.4 times or more the maximum pitch P3 of the third land portion 4C. By making the maximum width W3 of the third land portion 4C 1.4 times or more the maximum pitch P3 of the third land portion 4C, the density of the sipes 5 of the third land portion 4C can be increased, and the wet performance of the tire 1 can be improved. From this perspective, the maximum width W3 of the third land portion 4C is more preferably 1.5 times or more the maximum pitch P3 of the third land portion 4C.

[0035] The maximum width W3 of the third land portion 4C is preferably 3.0 times or less the maximum pitch P3 of the third land portion 4C. By making the maximum width W3 of the third land portion 4C 3.0 times or less the maximum pitch P3 of the third land portion 4C, the rigidity of the third land portion 4C can be increased, and the wear resistance of the tire 1 can be improved. From this perspective, the maximum width W3 of the third land portion 4C is more preferably 2.5 times or less the maximum pitch P3 of the third land portion 4C.

[0036] For these reasons, the maximum width W3 of the third land portions 4C is preferably 1.4 to 3.0 times the maximum pitch P3 of the third land portions 4C, and more preferably 1.5 to 2.5 times. Note that the combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.

[0037] Although not shown in the drawings, it is desirable that the sipes 5 extend in a zigzag pattern in the sipe depth direction. Such sipes 5 allow the wall surfaces to effectively support each other when a load is applied, and can suppress deformation of the land portion 4, thereby improving the rolling resistance and wear resistance of the tire 1.

[0038] 1 illustrates sipes 5 extending linearly in the tire axial direction, but the sipes 5 are not limited to this form. For example, the sipes 5 may extend in a zigzag pattern in the sipe longitudinal direction, or may be 3D sipes extending in a zigzag pattern in the sipe longitudinal direction and the sipe depth direction, or different types of sipes 5 may be mixed.

[0039] Such sipes 5 allow the wall surfaces to more effectively support each other when a load is applied, and can more reliably suppress deformation of the land portion 4, thereby further improving the rolling resistance performance and wear resistance performance of the tire 1.

[0040] Fig. 3 is a developed view of the tread portion 2 of another embodiment. As shown in Fig. 3, the sipes 5 may be inclined, for example, with respect to the tire axial direction. Such sipes 5 can facilitate drainage by smoothing the flow of water, thereby improving the wet performance of the tire 1.

[0041] The angle θ of the sipes 5 relative to the tire axial direction is preferably 25° or less. By making the angle θ of the sipes 5 25° or less, it is possible to prevent the land portions 4 at the communicating portions between the circumferential grooves 3 and the sipes 5 from forming acute angles, thereby suppressing the occurrence of localized uneven wear and chipping. From this perspective, the angle θ of the sipes 5 is more preferably 20° or less. Here, when the sipes 5 are not linear, the angle θ of the sipes 5 is the angle θ of a straight line connecting the start point and end point of the sipes 5.

[0042] It is desirable that the inclination direction of the sipes 5 in the first land portion 4A and the inclination direction of the sipes 5 in the second land portion 4B are different from each other. In this embodiment, the inclination direction of the sipes 5 in the third land portion 4C is the same as that of the sipes 5 in the first land portion 4A and is different from that of the sipes 5 in the second land portion 4B. Such sipes 5 improve drainage and also help to improve the noise performance of the tire 1.

[0043] 3 illustrates an example in which the angle θ of the sipes 5 of each of the multiple land portions 4 is the same, but this is not limited to this example, and the angle θ of the sipes 5 may be different for each land portion 4. For example, the angle θ of the sipes 5 of the first land portion 4A may be smaller than the angle θ of the sipes 5 of the second land portion 4B and the third land portion 4C. Such sipes 5 can both suppress uneven wear in the first land portion 4A, where uneven wear is likely to occur, and improve drainage in the second land portion 4B and the third land portion 4C, where ground pressure is high.

[0044] For example, the sipes 5 may include a mixture of sipes extending in the tire axial direction and sipes extending at an angle to the tire axial direction. Such sipes 5 can be appropriately set depending on the performance required of the tire 1.

[0045] 2, the maximum depth d1 of the sipes 5 in the tire radial direction is preferably 0.7 times or more the maximum groove depth d2 of the narrow groove portions 3a in the tire radial direction. By making the maximum depth d1 of the sipes 5 0.7 times or more the maximum groove depth d2 of the narrow groove portions 3a, the effect of improving drainage by the sipes 5 can be reliably achieved. From this perspective, the maximum depth d1 of the sipes 5 is more preferably 0.85 times or more the maximum groove depth d2 of the narrow groove portions 3a.

[0046] The maximum depth d1 of the sipes 5 is preferably 1.3 times or less the maximum groove depth d2 of the narrow groove portions 3a. By making the maximum depth d1 of the sipes 5 1.3 times or less the maximum groove depth d2 of the narrow groove portions 3a, it is possible to maintain good rigidity of the land portions 4. From this perspective, the maximum depth d1 of the sipes 5 is more preferably 1.15 times or less the maximum groove depth d2 of the narrow groove portions 3a.

[0047] For these reasons, the maximum depth d1 of the sipe 5 is preferably 0.7 to 1.3 times, and more preferably 0.85 to 1.15 times, the maximum groove depth d2 of the narrow groove portion 3a. The combination of the upper and lower limit values ​​of these numerical ranges can be selected arbitrarily.

[0048] The maximum groove depth d2 of the narrow groove portions 3a is preferably 0.25 or more times the maximum groove depth d3 in the tire radial direction of the circumferential grooves 3. By making the maximum groove depth d2 of the narrow groove portions 3a 0.25 or more times the maximum groove depth d3 of the circumferential grooves 3, deformation of the land portions 4 during contact with the ground can be reliably suppressed. From this perspective, the maximum groove depth d2 of the narrow groove portions 3a is more preferably 0.30 or more times the maximum groove depth d3 of the circumferential grooves 3.

[0049] The maximum groove depth d2 of the narrow groove portions 3a is preferably 0.70 times or less the maximum groove depth d3 of the circumferential groove 3. By making the maximum groove depth d2 of the narrow groove portions 3a 0.70 times or less the maximum groove depth d3 of the circumferential groove 3, the volume of the widened portions 3b can be increased, and a decrease in drainage performance in the later stages of wear can be reliably suppressed. From this perspective, the maximum groove depth d2 of the narrow groove portions 3a is more preferably 0.65 times or less the maximum groove depth d3 of the circumferential groove 3.

[0050] For these reasons, the maximum groove depth d2 of the narrow groove portion 3a is preferably 0.25 to 0.70 times, and more preferably 0.30 to 0.65 times, the maximum groove depth d3 of the circumferential groove 3. The combination of the upper and lower limit values ​​of these numerical ranges can be selected arbitrarily.

[0051] The circumferential groove 3 preferably includes a single arc-shaped inflection portion 3c between the narrow groove portion 3a and the widened portion 3b. Such a circumferential groove 3 smoothly changes when the narrow groove portion 3a disappears due to wear, and can suppress the occurrence of localized uneven wear and chipping.

[0052] The maximum groove width wg2 of the widened portion 3b is preferably 2.5 times or more the minimum groove width wg1 of the narrow groove portion 3a. By making the maximum groove width wg2 of the widened portion 3b 2.5 times or more the minimum groove width wg1 of the narrow groove portion 3a, it is possible to ensure a sufficient volume of the widened portion 3b and reliably suppress a decrease in drainage performance in the later stages of wear. From this perspective, the maximum groove width wg2 of the widened portion 3b is more preferably 3.0 times or more the minimum groove width wg1 of the narrow groove portion 3a.

[0053] The maximum groove width wg2 of the widened portion 3b is preferably 7.0 times or less the minimum groove width wg1 of the narrow groove portion 3a. By making the maximum groove width wg2 of the widened portion 3b 7.0 times or less the minimum groove width wg1 of the narrow groove portion 3a, it is possible to prevent the widened portion 3b from becoming excessively large and maintain high rigidity of the land portion 4. From this perspective, the maximum groove width wg2 of the widened portion 3b is more preferably 5.0 times or less the minimum groove width wg1 of the narrow groove portion 3a.

[0054] For these reasons, the maximum groove width wg2 of the widened portion 3b is preferably 2.5 to 7.0 times, and more preferably 3.0 to 5.0 times, the minimum groove width wg1 of the narrow groove portion 3a. The combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.

[0055] The minimum groove width wg1 of the narrow groove portion 3a is preferably 1.0 mm or more. When the minimum groove width wg1 of the narrow groove portion 3a is 1.0 mm or more, drainage performance at the initial stage of wear can be improved. From this perspective, the minimum groove width wg1 of the narrow groove portion 3a is more preferably 1.5 mm or more.

[0056] The minimum groove width wg1 of the narrow groove portion 3a is preferably 3.0 mm or less. By setting the minimum groove width wg1 of the narrow groove portion 3a to 3.0 mm or less, deformation of the land portion 4 during contact with the ground can be reliably suppressed. From this perspective, the minimum groove width wg1 of the narrow groove portion 3a is more preferably 2.5 mm or less.

[0057] For these reasons, the minimum groove width wg1 of the narrow groove portion 3a is preferably 1.0 to 3.0 mm, and more preferably 1.5 to 2.5 mm. The combination of the upper and lower limits of these numerical ranges can be selected arbitrarily.

[0058] Fig. 4 is a cross-sectional view of a circumferential groove 6 of the second embodiment. The same elements as those of the above-described embodiment are denoted by the same reference numerals, and a description thereof will be omitted. As shown in Fig. 4, the circumferential groove 6 of the second embodiment includes, similar to the above-described circumferential groove 3, a narrow groove portion 6a having a narrow groove width on the outer side in the tire radial direction, and a widened portion 6b having a wider groove width on the inner side in the tire radial direction than the narrow groove portion 6a.

[0059] In the circumferential groove 6, like the above-described circumferential groove 3, the land portions 4 adjacent to the narrow groove portions 6a come into contact with each other when a load is applied, thereby suppressing deformation of the land portions 4 when the tire contacts the ground, and improving the rolling resistance performance and wear resistance performance of the tire 1. In addition, the widened portions 6b widen the groove width in the later stage of wear, which helps to suppress a decrease in drainage performance in the later stage of wear and improve the wet performance of the tire 1.

[0060] The circumferential groove 6 preferably includes a single arc-shaped inflection portion 6c between the narrow groove portion 6a and the widened portion 6b, similar to the above-described circumferential groove 3. In this type of circumferential groove 6, similar to the above-described circumferential groove 3, the change when the narrow groove portion 6a disappears due to wear is smooth, and the occurrence of localized uneven wear and chipping can be suppressed.

[0061] The circumferential groove 6 of the second embodiment includes a chamfered portion 6d that extends in a tapered shape from the contact patch 2a on the radially outer side of the narrow groove portion 6a. Such a circumferential groove 6 can improve drainage in the early stage of wear without reducing the rigidity of the land portion 4, thereby improving the wet performance of the tire 1.

[0062] In the second embodiment, the opening width wg3 of the chamfered portion 6d of the circumferential groove 6 is larger than the maximum groove width wg2 of the widened portion 6b. Such a chamfered portion 6d can more reliably improve drainage performance in the early stage of wear.

[0063] Fig. 5 is a cross-sectional view of a circumferential groove 7 of a third embodiment. The same elements as those of the above-described embodiments are given the same reference numerals, and their description will be omitted. As shown in Fig. 5, the circumferential groove 7 of the third embodiment includes, like the above-described circumferential groove 6, a narrow groove portion 7a having a narrow groove width on the outer side in the tire radial direction, and a widened portion 7b having a wider groove width on the inner side in the tire radial direction than the narrow groove portion 7a.

[0064] In the circumferential groove 7, like the above-described circumferential groove 6, the land portions 4 adjacent to the narrow groove portions 7a come into contact with each other when a load is applied, thereby suppressing deformation of the land portions 4 when the tire contacts the ground, and improving the rolling resistance performance and wear resistance of the tire 1. In addition, the widened portions 7b widen the groove width in the later stage of wear, which helps to suppress a decrease in drainage performance in the later stage of wear and improve the wet performance of the tire 1.

[0065] The circumferential groove 7 of the third embodiment includes an inflection portion 7c between the narrow groove portion 7a and the widened portion 7b, and a chamfered portion 7d extending in a tapered shape from the contact patch 2a on the radially outer side of the narrow groove portion 6a, similar to the above-described circumferential groove 6. Similar to the above-described circumferential groove 6, this circumferential groove 7 can suppress the occurrence of localized uneven wear and chipping, and can also improve drainage in the early stages of wear.

[0066] The maximum groove width wg2 of the widened portion 7b of the circumferential groove 7 of the third embodiment is larger than the opening width wg3 of the chamfered portion 7d. Such widened portion 7b can more reliably improve drainage performance in the later stage of wear.

[0067] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified and practiced in various ways.

[0068] [Note] The present invention is as follows.

[0069] [Invention 1] A tire having a tread portion, The tread portion has a plurality of circumferential grooves extending in a tire circumferential direction and a plurality of land portions separated by the plurality of circumferential grooves, At least one of the plurality of circumferential grooves includes a narrow groove portion having a narrow groove width on the outer side in the tire radial direction and a widened groove portion having a widened groove width on the inner side in the tire radial direction than the narrow groove portion, the plurality of land portions include a first land portion located outermost in the tire axial direction and a second land portion located more inward in the tire axial direction than the first land portion, the first land portion and the second land portion each have a plurality of sipes crossing the first land portion and the second land portion, a maximum pitch in the tire circumferential direction between the sipes adjacent in the tire circumferential direction of the second land portion is smaller than a maximum pitch in the tire circumferential direction between the sipes adjacent in the tire circumferential direction of the first land portion; tire.

[0070] [Invention 2] The tire according to invention 1, wherein the maximum width of the second land portion in the tire axial direction is 1.4 to 3.0 times the maximum pitch of the second land portion.

[0071] [Invention 3] The tire according to invention 1 or 2, wherein the maximum width of the first land portion in the tire axial direction is 1.0 to 3.0 times the maximum pitch of the first land portion.

[0072] [Invention 4] The tire according to any one of Inventions 1 to 3, wherein the maximum depth of the sipe in the tire radial direction is 0.7 to 1.3 times the maximum groove depth of the narrow groove portion in the tire radial direction.

[0073] [Invention 5] 5. The tire according to any one of claims 1 to 4, wherein the sipes extend in a zigzag pattern in the sipe depth direction.

[0074] [Invention 6] 6. The tire according to any one of claims 1 to 5, wherein the sipes extend in a zigzag pattern in the longitudinal direction of the sipes.

[0075] [Invention 7] 7. The tire according to any one of claims 1 to 6, wherein the sipes are inclined at an angle of 25° or less with respect to the tire axial direction.

[0076] [Invention 8] The tire according to any one of Inventions 1 to 7, wherein the maximum groove width of the widened portion is 2.5 to 7.0 times the minimum groove width of the narrow groove portion.

[0077] [Invention 9] The tire according to any one of claims 1 to 8, wherein the circumferential groove including the narrow groove portion and the widened portion includes a single arc-shaped inflection portion between the narrow groove portion and the widened portion.

[0078] [Invention 10] The tire according to any one of claims 1 to 9, wherein the circumferential groove including the narrow groove portion and the widened portion includes a chamfered portion extending tapered from the ground contact surface on the radially outer side of the narrow groove portion. [Explanation of symbols]

[0079] 1 tire 2 Tread section 3 Circumferential groove 4 Land 4A 1st Land Department 4B 2nd Land Department 5 sipes

Claims

1. A tire having a tread portion, The tread portion has a plurality of circumferential grooves extending in a tire circumferential direction and a plurality of land portions separated by the plurality of circumferential grooves, At least one of the plurality of circumferential grooves includes a narrow groove portion having a narrow groove width on an outer side in the tire radial direction, and a widened portion having a wide groove width on an inner side in the tire radial direction than the narrow groove portion, the plurality of land portions include a first land portion located outermost in the tire axial direction and a second land portion located more inward in the tire axial direction than the first land portion, the first land portion and the second land portion each have a plurality of sipes crossing the first land portion and the second land portion, a maximum pitch in the tire circumferential direction between the sipes adjacent in the tire circumferential direction of the second land portion is smaller than a maximum pitch in the tire circumferential direction between the sipes adjacent in the tire circumferential direction of the first land portion; tire.

2. The tire according to claim 1, wherein the maximum width of the second land portion in the tire axial direction is 1.4 to 3.0 times the maximum pitch of the second land portion.

3. The tire according to claim 1 or 2, wherein the maximum width of the first land portion in the tire axial direction is 1.0 to 3.0 times the maximum pitch of the first land portion.

4. 3. The tire according to claim 1, wherein the maximum depth of the sipe in the tire radial direction is 0.7 to 1.3 times the maximum groove depth of the narrow groove portion in the tire radial direction.

5. The tire according to claim 1 or 2, wherein the sipes extend in a zigzag pattern in a sipe depth direction.

6. The tire according to claim 5 , wherein the sipes extend in a zigzag pattern in the sipe longitudinal direction.

7. The tire according to claim 1 or 2, wherein the sipes are inclined at an angle of 25° or less with respect to the tire axial direction.

8. 3. The tire according to claim 1, wherein the maximum groove width of the widened portion is 2.5 to 7.0 times the minimum groove width of the narrow groove portion.

9. The tire according to claim 1 or 2, wherein the circumferential groove including the narrow groove portion and the widened portion includes a single arc-shaped inflection portion between the narrow groove portion and the widened portion.

10. The tire according to claim 1 or 2, wherein the circumferential groove including the narrow groove portion and the widened portion includes a chamfered portion extending in a tapered shape from the ground contact surface on an outer side of the narrow groove portion in the tire radial direction.

Images