tire

Abstract

To improve partial wear resistance performance of a tire in which a fixing direction to a vehicle is specified.SOLUTION: A tread part 2 of a tire comprises: a plurality of circumferential grooves 3; and a plurality of land parts 9 separated by the plurality of circumferential grooves 3. The plurality of land parts 9 includes: a crown land part 10; a first middle land part 11; and a second middle land part 12. The crown land part 10, the first middle land part 11, and the second middle land part 12 respectively include: a crown profile 45; a first middle profile 46; and a second middle profile 47. Their profiles respectively protrude in a tire radial direction outer side compared with the reference tread profile 44. The maximum excrescence quantity of the crown profile 45 is larger than that of the first middle profile 46. The maximum excrescence quantity of the second middle profile 47 is larger than that of the crown profile 45.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The following Patent Document 1 proposes a tire in which the tread surface of the middle land portion protrudes radially outward from the standard tread profile. By specifying the tread surface of the middle land portion as described above, this tire is expected to reduce the ground pressure acting on the vertical edges on both sides of the middle land portion, improving fuel efficiency and braking performance on dry roads. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-111261 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, currently, tires have been proposed that are designed to be mounted in a specified direction on a vehicle in order to fully utilize various tire performance characteristics. In such tires, when the tread surface of the land portion is made to protrude radially outward from the standard tread profile as in the tire of Patent Document 1, certain land portions tend to be easily worn unevenly.

[0005] The present invention has been devised in view of the above-mentioned problems, and has as its main object to improve the uneven wear resistance of a tire whose mounting direction on a vehicle is specified. [Means for solving the problem]

[0006] The present invention relates to a tire having a tread portion whose mounting direction on a vehicle is specified, the tread portion including a first tread edge that is on the inside of the vehicle when mounted on the vehicle, a second tread edge that is on the outside of the vehicle when mounted on the vehicle, a plurality of circumferential grooves that extend continuously in the tire circumferential direction between the first tread edge and the second tread edge, and a plurality of land portions divided into the plurality of circumferential grooves, the plurality of land portions including a crown land portion, a first middle land portion adjacent to the first tread edge side of the crown land portion, and a second middle land portion adjacent to the second tread edge side of the crown land portion, and the tire rotational speed in a normal state where the tire is mounted on a normal rim at a normal internal pressure and is unloaded is described. In a meridian cross section including the rolling axis, the crown land portion, the first middle land portion and the second middle land portion each have a crown profile, a first middle profile and a second middle profile that protrude radially outward from a reference tread profile, and a maximum protrusion amount of the crown profile from the reference tread profile is greater than a maximum protrusion amount of the second middle profile from the reference tread profile, and a maximum protrusion amount of the first middle profile from the reference tread profile is greater than a maximum protrusion amount of the crown profile from the reference tread profile.

[0007] In the tire of the present invention, it is preferable that the maximum protrusion amount of each of the crown profile, the first middle profile and the second middle profile is 0.15 mm or less.

[0008] In the tire of the present invention, the maximum protrusion amount of the crown profile is desirably 60% to 75% of the maximum protrusion amount of the first middle profile.

[0009] In the tire of the present invention, it is preferable that the maximum protrusion amount of the second middle profile is 25% to 40% of the maximum protrusion amount of the first middle profile.

[0010] In the tire of the present invention, each of the crown land portion, the first middle land portion and the second middle land portion has a plurality of lateral grooves extending in the tire axial direction, and it is preferable that the number of pitches of the lateral grooves around the entire circumference of the tire in each of the crown land portion, the first middle land portion and the second middle land portion is 75 to 100.

[0011] In the tire of the present invention, it is desirable that the multiple circumferential grooves include a first shoulder circumferential groove provided closest to the first tread end and a second shoulder circumferential groove provided closest to the second tread end, and that the maximum groove width of the second shoulder circumferential groove is smaller than the maximum groove width of the first shoulder circumferential groove.

[0012] In the tire of the present invention, the maximum groove width of the second shoulder circumferential groove is desirably 55% to 65% of the maximum groove width of the first shoulder circumferential groove.

[0013] In the tire of the present invention, it is preferable that each of the first middle land portion and the second middle land portion is provided with a plurality of lateral grooves inclined at an angle of 10 to 30 degrees with respect to the tire axial direction. Effect of the Invention

[0014] By adopting the above-mentioned configuration, the tire of the present invention can improve uneven wear resistance. [Brief description of the drawings]

[0015] [Figure 1] 1 is a development view of a tread portion of a tire according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a meridian cross-sectional view of the tire of FIG. 1. [Diagram 3] 3 is an enlarged cross-sectional view of a crown land portion, a first middle land portion, and a second middle land portion of FIG. 2. [Figure 4] 2 is an enlarged view of a crown land portion, a first middle land portion, and a second middle land portion in FIG. 1. [Diagram 5]FIG. 2 is an enlarged view of a first shoulder land portion of FIG. [Figure 6] FIG. 3 is an enlarged view of the second shoulder land portion of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a development view of a tread portion 2 of a tire 1 showing one embodiment of the present invention. The tire 1 of this embodiment is suitably used as, for example, a pneumatic tire for winter passenger cars. However, the present invention is not limited to such an embodiment.

[0017] 1, a tire 1 of the present invention has a tread portion 2 in which the mounting orientation on a vehicle is specified, for example. The tread portion 2 includes a first tread edge T1 that is on the inside of the vehicle when the tire 1 is mounted on the vehicle, and a second tread edge T2 that is on the outside of the vehicle when the tire 1 is mounted on the vehicle. The mounting orientation on the vehicle is indicated, for example, by letters or symbols on a sidewall portion (not shown).

[0018] The first tread edge T1 and the second tread edge T2 are the axially outermost contact points when the tire 1 in a normal state is loaded with a normal load and contacts the ground on a flat surface with a camber angle of 0°. The normal state refers to a state in which the tire is mounted on a normal rim, inflated to a normal internal pressure, and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal state.

[0019] For tires with various standards, the "genuine rim" is the rim that is specified for each tire by the standard system that includes the standard on which the tire is based, for example, "standard rim" for JATMA, "design rim" for TRA, and "measuring rim" for ETRTO. For tires without standards, the "genuine rim" means a rim that can fully demonstrate the performance of the tire, for example, the rim recommended by the manufacturer.

[0020] For tires with various standards, the "normal internal pressure" is the pressure set for each tire by the standard system including the standard on which the tire is based, such as the "maximum pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO. For tires without standards, the "normal rim" means the internal pressure at which the tire can perform to its full potential, for example, the internal pressure recommended by the manufacturer.

[0021] For tires with various standards, the "normal load" is the load specified for each tire by each standard in the standard system including the standard on which the tire is based, and is the "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. For tires without a standard, the "normal load" refers to the load acting on a tire in its standard mounting state. The "standard mounting state" refers to a state in which the tire is mounted on a standard vehicle corresponding to the intended use of the tire, and the vehicle is stationary on a flat road surface in a drivable state.

[0022] The tread portion 2 includes a plurality of circumferential grooves 3 extending continuously in the tire circumferential direction between a first tread edge T1 and a second tread edge T2, and a plurality of land portions 9 separated by the plurality of circumferential grooves 3.

[0023] The circumferential grooves 3 include a first shoulder circumferential groove 6, a second shoulder circumferential groove 7, a first crown circumferential groove 4, and a second crown circumferential groove 5. The first shoulder circumferential groove 6 is provided closest to the first tread edge T1 among the multiple circumferential grooves 3. The second shoulder circumferential groove 7 is provided closest to the second tread edge T2 among the multiple circumferential grooves 3. The first crown circumferential groove 4 is provided between the first shoulder circumferential groove 6 and the tire equator C. The second crown circumferential groove 5 is provided between the second shoulder circumferential groove 7 and the tire equator C.

[0024] The axial distance L1 from the tire equator C to the groove centerline of the first shoulder circumferential groove 6 or the second shoulder circumferential groove 7 is preferably, for example, 25% to 35% of the tread width TW. The axial distance L2 from the tire equator C to the groove centerline of the first crown circumferential groove 4 or the second crown circumferential groove 5 is preferably, for example, 5% to 15% of the tread width TW. The tread width TW is the axial distance from the first tread edge T1 to the second tread edge T2 in the normal state.

[0025] Each circumferential groove 3 of this embodiment extends, for example, linearly along the tire circumferential direction, or in a wavy shape with the groove center line slightly vibrating.

[0026] The groove width W1 of each circumferential groove 3 is 3.0 mm or more, and is preferably, for example, 3.0% to 7.0% of the tread width TW. In this specification, the groove width of the circumferential groove 3 is the distance between the groove edges on both sides in the direction perpendicular to the groove center line in the normal state. The groove edge is the boundary between the groove and the tread surface of the land portion in the normal state.

[0027] The multiple land portions 9 include a crown land portion 10, a first middle land portion 11, and a second middle land portion 12. In addition to these, the multiple land portions 9 in this embodiment include a first shoulder land portion 13 and a second shoulder land portion 14. The crown land portion 10 is divided between the first crown circumferential groove 4 and the second crown circumferential groove 5, and is provided on the tire equator C in this embodiment. The first middle land portion 11 is adjacent to the first tread edge T1 side of the crown land portion 10, and is divided between the first crown circumferential groove 4 and the first shoulder circumferential groove 6. The second middle land portion 12 is adjacent to the second tread edge T2 side of the crown land portion 10, and is divided between the second crown circumferential groove 5 and the second shoulder circumferential groove 7.

[0028] The first shoulder land portion 13 is defined on the axially outer side of the first shoulder circumferential groove 6 and includes the first tread edge T1. The second shoulder land portion 14 is defined on the axially outer side of the second shoulder circumferential groove 7 and includes the second tread edge T2.

[0029] Fig. 2 shows a meridian cross section of the tire 1 of this embodiment in the normal state. As shown in Fig. 2, the tread portion 2 is configured with a profile curved in a direction convex toward the outside in the tire radial direction.

[0030] Fig. 3 shows an enlarged cross-sectional view of the crown land portion 10, the first middle land portion 11, and the second middle land portion 12 in Fig. 2. As shown in Fig. 3, the crown land portion 10, the first middle land portion 11, and the second middle land portion 12 each have a crown profile 45, a first middle profile 46, and a second middle profile 47 that protrude radially outward from a reference tread profile 44. In Fig. 3, the curvature of each of the crown profile 45, the first middle profile 46, and the second middle profile 47 is shown larger than the actual curvature in order to facilitate understanding of the features of the invention.

[0031] The reference tread profile 44 in the first middle land portion 11 corresponds to a circular arc having a single radius of curvature that passes through both ends of the tread surface of the land portion and a groove edge on the tire equator C side of a circumferential groove (in this embodiment, the first crown circumferential groove 4) adjacent to the axially inner side of the first middle land portion 11. The reference tread profile 44 in the second middle land portion 12 is defined in the same manner.

[0032] The reference tread profile 44 in the crown land portion 10 corresponds to a first arc passing through both ends of the tread surface of the crown land portion 10 and a groove edge on the first tread end T1 side of the first crown circumferential groove 4, or a second arc passing through both ends of the tread surface of the crown land portion 10 and a groove edge on the second tread end T2 side of the second crown circumferential groove 5, whichever has a larger radius of curvature. In this embodiment, the first arc and the second arc are configured to have the same radius of curvature.

[0033] In the present invention, the maximum protrusion amount d3 of the crown profile 45 from the reference tread profile 44 is greater than the maximum protrusion amount d2 of the second middle profile 47 from the reference tread profile 44. Also, the maximum protrusion amount d1 of the first middle profile 46 from the reference tread profile 44 is greater than the maximum protrusion amount d3 of the crown profile 45 from the reference tread profile 44. By adopting the above-mentioned configuration, the tire 1 of the present invention can improve uneven wear resistance. The following mechanism is presumed to be the reason for this.

[0034] In the present invention, the profile of each land portion 9 protrudes from the standard tread profile 44, thereby reducing the ground contact pressure acting on the longitudinal edges of the land portion 9 and suppressing uneven wear near the longitudinal edges.

[0035] On the other hand, when the above-mentioned profile is adopted for the tread portion 2 whose mounting direction on the vehicle is specified, uneven wear tends to occur easily in the land portion slightly inside the vehicle from the tire equator (the land portion corresponding to the first middle land portion 11 in this embodiment). This is presumably because a relatively large ground contact pressure acts on the above-mentioned land portion due to the slight negative camber given to a general vehicle.

[0036] In the present invention, by setting the maximum protrusion amount of the profile of each land portion 9 to the above relationship, the ground contact pressure acting on the vertical edges of each land portion 9 can be mitigated in a well-balanced manner, and uneven wear of the first middle land portion 11 in particular can be effectively suppressed. It is believed that the tire 1 of the present invention can exhibit excellent uneven wear resistance due to this mechanism.

[0037] A more detailed configuration of this embodiment will be described below. Each configuration described below shows a specific aspect of this embodiment. Therefore, it goes without saying that the present invention can achieve the above-mentioned effects even if it does not have the configuration described below. In addition, even if any one of the configurations described below is applied alone to the tire of the present invention having the above-mentioned characteristics, an improvement in performance according to each configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, a composite improvement in performance according to each configuration can be expected.

[0038] 1, it is desirable that the maximum groove width W7 of the second shoulder circumferential groove 7 is smaller than the maximum groove width W6 of the first shoulder circumferential groove 6. Specifically, the groove width W7 of the second shoulder circumferential groove 7 is 55% to 65% of the groove width W6 of the first shoulder circumferential groove 6. This reduces the air column resonance sound of the second shoulder circumferential groove 7, which has a large effect on noise performance.

[0039] 3, the maximum protrusion amount d3 of the crown profile 45, the maximum protrusion amount d1 of the first middle profile 46, and the maximum protrusion amount d2 of the second middle profile are each 0.15 mm or less, thereby suppressing uneven wear in the axial center of the land portion.

[0040] The maximum protrusion amount d3 of the crown profile 45 is preferably 60% to 75% of the maximum protrusion amount d1 of the first middle profile 46. Also, the maximum protrusion amount d2 of the second middle profile 47 is preferably 25% to 40% of the maximum protrusion amount d1 of the first middle profile 46. This makes the ground pressure acting on each land portion uniform, suppressing uneven wear.

[0041] Fig. 4 shows an enlarged view of the crown land portion 10, the first middle land portion 11, and the second middle land portion 12. As shown in Fig. 4, each of the crown land portion 10, the first middle land portion 11, and the second middle land portion 12 has a lateral groove extending in the tire axial direction. In each of the crown land portion 10, the first middle land portion 11, and the second middle land portion 12, the pitch number of the lateral groove over the entire circumference of the tire is, for example, 75 to 100, and preferably 80 to 90. This improves uneven wear resistance and noise performance in a well-balanced manner.

[0042] The crown land portion 10 is provided with a plurality of crown lateral grooves 15. The crown lateral grooves 15 are inclined in a first direction (slanting downward to the right in each drawing of this specification) with respect to the tire axial direction, and completely cross the crown land portion 10 in the tire axial direction.

[0043] The crown lateral groove 15 includes a first end portion 16 and a second end portion 17 in the tire axial direction, and a central portion 18 disposed between the first end portion 16 and the second end portion 17. The groove width of the central portion 18 of the crown lateral groove 15 is smaller than the groove width of the first end portion 16 and the groove width of the second end portion 17.

[0044] The maximum groove width of the center portion 18 of the crown lateral groove 15 is, for example, 15% or less of the maximum groove width of the first end portion 16 and the second end portion 17, and is preferably 3% to 15%. As a more preferable embodiment, the center portion 18 of the crown lateral groove 15 of this embodiment is configured as a narrow groove portion having a groove width of 1.5 mm or less. This allows the rigidity of the crown land portion 10 to be maintained, and improves the steering stability on dry road surfaces (hereinafter, sometimes simply referred to as "steering stability"). Hereinafter, in this specification, unless otherwise specified, the "narrow groove portion" refers to a portion of the groove having a groove width of 1.5 mm or less. Also, the "narrow groove" refers to a groove having a groove width of 1.5 mm or less throughout. Also, grooves not described as narrow grooves have a groove width greater than 1.5 mm. In each lateral groove of this embodiment, the portion not described as narrow groove portion has a groove width of, for example, about 2.0 to 4.0 mm.

[0045] For example, the central portion 18 crosses the axial center position of the crown land portion 10. For example, the axial length L3 of the central portion 18 is 40% to 60% of the axial width W2 of the crown land portion 10. Such a central portion 18 improves on-snow performance and noise performance in a well-balanced manner.

[0046] The central portion 18 is inclined in the first direction with respect to the tire axial direction. The angle θ2 of the central portion 18 with respect to the tire axial direction is, for example, 45° or less, and desirably 35 to 45°.

[0047] The axial length of the first end portion 16 and the axial length of the second end portion 17 are each shorter than the axial length L3 of the central portion 18 and are 20% to 30% of the axial width W2 of the crown land portion 10.

[0048] The first end 16 and the second end 17 are inclined in the first direction with respect to the tire axial direction. The angle of the first end 16 and the second end 17 with respect to the tire axial direction is smaller than the angle of the central portion 18 with respect to the tire axial direction, for example, 10 to 25°. As a result, it is desirable that the crown lateral groove 15 includes a portion that is formed by the first end 16 and the central portion 18 and is slightly convex on one side in the tire circumferential direction, and a portion that is formed by the second end 17 and the central portion 18 and is slightly convex on the other side in the tire circumferential direction. In such a crown lateral groove 15, the first end 16 and the second end 17 form a solid snow pillar together with the circumferential groove, and the traction performance on snow can be improved.

[0049] By providing the crown lateral groove 15 with the above-mentioned configuration, the angle of the straight line connecting both ends of the crown lateral groove 15 with respect to the tire axial direction is, for example, 45° or less, and preferably 20 to 40°.

[0050] A one-pitch length P1 of the multiple crown lateral grooves 15 in the tire circumferential direction is, for example, 60% to 90% of the axial width W2 of the crown land portion 10. This improves on-snow performance and noise performance in a well-balanced manner.

[0051] A first crown narrow groove 23 and a second crown narrow groove 24 are provided between two crown lateral grooves 15 adjacent to each other in the tire circumferential direction. The first crown narrow groove 23 extends from the first crown circumferential groove 4 and terminates in the crown land portion 10. The second crown narrow groove 24 extends from the second crown circumferential groove 5 and terminates in the crown land portion 10.

[0052] The axial length of the first crown narrow groove 23 is, for example, 80% to 120% of the axial length of the first end 16 of the crown lateral groove 15. The second crown narrow groove 24 is terminated, for example, closer to the first crown circumferential groove 4 than the second end 17 of the crown lateral groove 15. Such first crown narrow groove 23 and second crown narrow groove 24 disperse the frequency of noise generated when the crown land portion 10 contacts the ground, improving noise performance.

[0053] The first crown narrow groove 23 and the second crown narrow groove 24 are inclined in a first direction with respect to the tire axial direction. The angle of the first crown narrow groove 23 with respect to the tire axial direction and the angle of the second crown narrow groove 24 with respect to the tire axial direction are smaller than the angle of the center portion 18 of the crown lateral groove 15 with respect to the tire axial direction. On the other hand, the angle difference between the first crown narrow groove 23 and the second crown narrow groove 24 and the center portion 18 is, for example, 15° or less, and preferably 10° or less. Specifically, the first crown narrow groove 23 and the second crown narrow groove 24 are inclined at an angle of 30 to 40° with respect to the tire axial direction.

[0054] The first middle land portion 11 is provided with a plurality of first middle lateral grooves 20. The first middle lateral grooves 20 are inclined in a second direction (upward and to the right in each drawing of this specification) opposite to the first direction with respect to the tire axial direction, and completely cross the first middle land portion 11 in the tire axial direction.

[0055] The first middle lateral grooves 20 are arranged at an angle different from the crown lateral grooves 15 with respect to the tire axial direction. This can reliably prevent the noise generated by each lateral groove from resonating. The angle of the first middle lateral grooves 20 with respect to the tire axial direction is, for example, 10 to 30 degrees. Such first middle lateral grooves 20 are useful for further improving noise performance.

[0056] In this embodiment, the crown lateral groove 15 and the first middle lateral groove 20 are adjacent to each other in the tire axial direction, so that in a plan view of the tread, a straight line connecting both ends of the crown lateral groove 15 and a straight line connecting both ends of the first middle lateral groove 20 intersect within the first crown circumferential groove 4. In a more preferable embodiment, a region obtained by projecting the connecting portion between the crown lateral groove 15 and the first crown circumferential groove 4 parallel to the tire axial direction overlaps with the connecting portion between the first middle lateral groove 20 and the first crown circumferential groove 4. This allows the crown lateral groove 15 and the first middle lateral groove 20 to form solid snow columns at the connecting portion with the first crown circumferential groove 4, thereby providing excellent on-snow performance.

[0057] In this embodiment, the first middle land portion 11 is provided with a plurality of first middle narrow grooves 26. The first middle narrow grooves 26 completely cross the first middle land portion 11 in the tire axial direction, and are provided alternately with the first middle lateral grooves 20 in the tire circumferential direction.

[0058] The first middle narrow groove 26 is inclined in the second direction with respect to the tire axial direction, for example. The first middle lateral groove 20 of this embodiment extends along the first middle lateral groove 20, and the angle difference therebetween is set to 5° or less. The first middle narrow groove 26 is also arranged at an angle with respect to the tire axial direction smaller than those of the first crown narrow groove 23 and the second crown narrow groove 24. Specifically, the angle of the first middle narrow groove 26 with respect to the tire axial direction is 10 to 30°.

[0059] In the second middle land portion 12, a plurality of second middle lateral grooves 30 and second middle narrow grooves 31 are provided alternately in the tire circumferential direction.

[0060] The second middle lateral grooves 30 are, for example, inclined in a second direction with respect to the tire axial direction, and completely cross the second middle land portion 12 in the tire axial direction. The second middle lateral grooves 30 are preferably arranged at an angle with respect to the tire axial direction smaller than the central portion 18 (shown in FIG. 2) of the crown lateral grooves 15. The angle of the second middle lateral grooves 30 with respect to the tire axial direction is, for example, 10 to 30 degrees. This makes it possible to suppress resonance of noise generated by the second middle lateral grooves 30 and the crown lateral grooves 15.

[0061] The second middle lateral groove 30 includes, for example, an inner groove portion 30a extending from the second crown circumferential groove 5 and an outer narrow groove portion 30b extending from the outer end of the inner groove portion 30a to the second shoulder circumferential groove 7.

[0062] For example, the inner groove portion 30a crosses the axial center position of the second middle land portion 12. The axial length L4 of the inner groove portion 30a is, for example, 60% to 90% of the axial width W3 of the second middle land portion 12. Such an inner groove portion 30a improves on-snow performance and uneven wear resistance in a well-balanced manner.

[0063] In this embodiment, it is desirable that the projected area of ​​the inner groove portion 30a extended along its length overlaps the communicating portion between the second crown circumferential groove 5 and the crown lateral groove 15. This further improves the on-snow performance.

[0064] The outer narrow groove portion 30b extends, for example, linearly from the inner groove portion 30a to the second shoulder circumferential groove 7 while being inclined in the second direction.

[0065] The second middle narrow groove 31 is, for example, inclined in the second direction with respect to the tire axial direction and completely crosses the second middle land portion 12 in the tire axial direction. The second middle narrow groove 31 of this embodiment extends, for example, along the second middle lateral groove 30, and the angle difference therebetween is 5° or less. Such a second middle narrow groove 31 can improve on-snow performance while suppressing uneven wear of the second middle land portion 12.

[0066] Fig. 5 shows an enlarged view of the first shoulder land portion 13. As shown in Fig. 5, in the first shoulder land portion 13, first shoulder lateral grooves 35 and first shoulder narrow grooves 36 are provided alternately in the tire circumferential direction.

[0067] For example, the first shoulder lateral groove 35 extends at least from the first tread edge T1 to the first shoulder circumferential groove 6. For example, the first shoulder lateral groove 35 is curved convexly toward one side in the tire circumferential direction.

[0068] The first shoulder lateral groove 35 includes, for example, a main body portion 35a on the first tread edge T1 side, and an inner end portion 35b extending from the axially inner end of the main body portion 35a to the first shoulder circumferential groove 6.

[0069] For example, the main body portion 35a of the first shoulder lateral groove 35 crosses the axial center position of the first shoulder land portion 13. The axial length L5 of the main body portion 35a is, for example, 60% to 80% of the axial width W4 of the first shoulder land portion 13. This improves on-snow performance and noise performance in a well-balanced manner.

[0070] The inner end 35b of the first shoulder lateral groove 35 has a groove width smaller than that of the main body portion 35a. The groove width of the inner end 35b is preferably 3% to 15% of the groove width of the main body portion 35a. In this embodiment, the inner end 35b of the first shoulder lateral groove 35 is configured as a narrow groove portion with a groove width of 1.5 mm or less. This reduces the amount of air passing through the first shoulder lateral groove 35, improving noise performance.

[0071] It is desirable that the axial length L6 of the inner end 35b of the first shoulder lateral groove 35 is smaller than the axial length L3 (shown in FIG. 4) of the central portion 18 of the crown lateral groove 15. Specifically, the length L6 of the inner end 35b is 40% to 60% of the length L3 of the central portion 18. This makes it possible to suppress resonance of noise generated by the crown lateral grooves 15 and the first shoulder lateral grooves 35.

[0072] For example, the first shoulder narrow groove 36 completely crosses the first shoulder land portion 13 in the tire axial direction. In this embodiment, the first shoulder narrow groove 36 is curved so as to be convex toward one side in the tire circumferential direction. In a more preferable embodiment, the first shoulder narrow groove 36 and the first shoulder lateral groove 35 extend parallel to each other, and the angle difference between them is 5° or less. Such a first shoulder narrow groove 36 can improve on-snow performance while suppressing uneven wear of the first shoulder land portion 13.

[0073] Fig. 6 shows an enlarged view of the second shoulder land portion 14. As shown in Fig. 6, in the second shoulder land portion 14, second shoulder lateral grooves 40 and second shoulder narrow grooves 41 are provided alternately in the tire circumferential direction.

[0074] The second shoulder lateral grooves 40, for example, extend at least from the second tread edge T2 axially inward and terminate within the second shoulder land portion 14. The axial length L7 of the second shoulder lateral grooves 40 is, for example, 75% to 90% of the axial width W5 of the second shoulder land portion 14. This makes it possible to suppress deterioration of noise performance due to air leaking from the second shoulder circumferential groove 7 toward the second tread edge T2.

[0075] The second shoulder lateral groove 40 includes, for example, a main body portion 40a on the second tread edge T2 side, and an inner end portion 40b that is continuous with the main body portion 40a on the axially inner side of the tire and has a groove width smaller than that of the main body portion 40a.

[0076] The main body portion 40a of the second shoulder lateral groove 40 crosses, for example, the axial center position of the second shoulder land portion 14. The axial length L8 of the main body portion 40a is, for example, 60% to 70% of the axial width W5 of the second shoulder land portion 14. This improves on-snow performance and noise performance in a well-balanced manner.

[0077] The inner end 40b of the second shoulder lateral groove 40 extends from the main body portion 40a and terminates within the second shoulder land portion 14. The axial length L9 of the inner end 40b is, for example, 15% to 25% of the axial width W5 of the second shoulder land portion 14. In a more preferable embodiment, the length L9 of the inner end 40b is shorter than the axial length L3 of the center portion 18 of the crown lateral groove 15. This makes it possible to suppress resonance of noise generated by each lateral groove.

[0078] The groove width of the inner end 40b of the second shoulder lateral groove 40 is preferably 3% to 15% of the groove width of the main body 40a of the second shoulder lateral groove 40. In this embodiment, the inner end 40b of the second shoulder lateral groove 40 is configured as a narrow groove portion with a groove width of 1.5 mm or less. This provides excellent steering stability.

[0079] For example, the second shoulder narrow groove 41 completely crosses the second shoulder land portion 14 in the tire axial direction. In this embodiment, the second shoulder narrow groove 41 and the second shoulder lateral groove 40 extend parallel to each other, and the angle difference between them is set to 5° or less.

[0080] Although the tire according to one embodiment of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment and can be modified and carried out in various aspects. EXAMPLES

[0081] A tire of size 225 / 65R17 having the basic pattern of FIG. 1 was prototyped based on the specifications of Table 1. As a comparative example, a tire having the same maximum protrusion amount of the crown land portion, the first middle land portion, and the second middle land portion was prototyped. The comparative example tire is substantially the same as the tire shown in FIG. 1 except for the above-mentioned points. The uneven wear resistance and noise performance of each test tire were tested. The common specifications and test methods of each test tire are as follows. Rim: 17×7.0J Tire pressure: front wheel 230kPa, rear wheel 210kPa Test vehicle: 1600cc, front-wheel drive Tire mounting position: All wheels

[0082] <Resistant to uneven wear> After the test vehicle was driven a certain distance, the wear of the tread (particularly the wear around the first middle land portion) was visually evaluated. The results were scored based on the wear of the comparative example being 100, with a higher score indicating better resistance to uneven wear.

[0083] <Noise performance> The noise performance of the test vehicle when it was driven on a dry road surface was evaluated by the driver. The results are expressed as an index with the noise performance of the comparative example being 100, and the higher the value, the better the noise performance. The test results are shown in Table 1.

[0084] [Table 1]

[0085] As a result of the test, it was confirmed that the tires of the examples exhibited excellent uneven wear resistance performance. It was also confirmed that the tires of the examples were excellent in noise performance. [Explanation of symbols]

[0086] 2 Tread section 3 Circumferential groove 9 Land 10 Crown Land Division 11 First Middle Track Division 12 Second Middle Track 44 Reference tread profile 45 Crown Profile 46 First Middle Profile 47 Second Middle Profile T1 First tread edge T2 Second tread edge

Claims

1. A tire having a tread portion with a specified mounting direction on a vehicle, the tread portion includes a first tread edge that is on the vehicle inner side when mounted on a vehicle, a second tread edge that is on the vehicle outer side when mounted on a vehicle, a plurality of circumferential grooves that extend continuously in the tire circumferential direction between the first tread edge and the second tread edge, and a plurality of land portions that are divided into the plurality of circumferential grooves, the plurality of land portions include a crown land portion, a first middle land portion adjacent to the first tread end side of the crown land portion, and a second middle land portion adjacent to the second tread end side of the crown land portion, In a meridian cross section including a tire rotation axis in a normal state in which the tire is mounted on a normal rim with normal internal pressure and is unloaded, the crown land portion, the first middle land portion and the second middle land portion each have a crown profile, a first middle profile and a second middle profile which protrude radially outward from a reference tread profile, a maximum protrusion amount of the crown profile from the reference tread profile is greater than a maximum protrusion amount of the second middle profile from the reference tread profile, a maximum protrusion amount of the first middle profile from the reference tread profile is greater than a maximum protrusion amount of the crown profile from the reference tread profile, The crown land portion is provided with a crown lateral groove, The crown lateral groove includes a first end portion and a second end portion in a tire axial direction, and a central portion disposed between the first end portion and the second end portion, The groove width of the central portion is smaller than the groove width of the first end portion and the groove width of the second end portion. tire.

2. 2. The tire of claim 1, wherein the maximum protrusion amount of each of the crown profile, the first middle profile, and the second middle profile is 0.15 mm or less.

3. 3. The tire according to claim 1, wherein the maximum protrusion amount of the crown profile is 60% to 75% of the maximum protrusion amount of the first middle profile.

4. 4. The tire according to claim 1, wherein the maximum protrusion amount of the second middle profile is 25% to 40% of the maximum protrusion amount of the first middle profile.

5. Each of the crown land portion, the first middle land portion, and the second middle land portion is provided with a plurality of lateral grooves extending in a tire axial direction, 5. The tire according to claim 1, wherein the number of pitches of the lateral grooves around the entire circumference of the tire is 75 to 100 in each of the crown land portion, the first middle land portion, and the second middle land portion.

6. The plurality of circumferential grooves include a first shoulder circumferential groove provided closest to the first tread end and a second shoulder circumferential groove provided closest to the second tread end, The tire according to claim 1 , wherein a maximum groove width of the second shoulder circumferential groove is smaller than a maximum groove width of the first shoulder circumferential groove.

7. The tire according to claim 6, wherein a maximum groove width of the second shoulder circumferential groove is 55% to 65% of a maximum groove width of the first shoulder circumferential groove.

8. 8. The tire according to claim 1, wherein each of the first middle land portion and the second middle land portion is provided with a plurality of lateral grooves inclined at an angle of 10 to 30 degrees with respect to the tire axial direction.

9. The second middle land portion is provided with a second middle narrow groove crossing the second middle land portion, 9. The tire according to claim 1, wherein the second middle narrow groove has a groove width of 1.5 mm or less.

10. The plurality of land portions include a second shoulder land portion adjacent to the second tread end side of the second middle land portion, the second shoulder land portion includes a second shoulder lateral groove, the second shoulder lateral groove includes a main body portion on the second tread edge side, and an inner end portion that is continuous with the main body portion on an axially inner side of the tire and has a groove width smaller than that of the main body portion, The tire according to claim 1 , wherein the inner end portion is terminated within the second shoulder land portion.

11. A tire as described in any one of claims 1 to 10, wherein the circumferential pitch length of the crown lateral groove is 60% to 90% of the axial width of the crown land portion.

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