Tire

Abstract

In a tire in which a direction of installation to a vehicle is designated, a cornering power endurance is improved. A tread portion (2) includes a plurality of circumferential grooves (3), and a plurality of land portions (9) divided by the plurality of circumferential grooves (3). The plurality of land portions (9) includes a crown land portion (10), a first intermediate land portion (11), and a second intermediate land portion (12). The crown land portion (10), the first intermediate land portion (11), and the second intermediate land portion (12) respectively have a crown profile (45) projecting to an outer side in a tire radial direction than a reference tread profile (44), a first intermediate profile (46), and a second intermediate profile (47). A maximum projection amount of the crown profile (45) is smaller than a maximum projection amount of the first intermediate profile (46). A maximum projection amount of the second intermediate profile (47) is smaller than the maximum projection amount of the crown profile (45).

Description

Technical Field

[0001] This invention relates to tires. Background Technology

[0002] Patent Document 1 describes a tire in which the tread of the middle land portion protrudes radially outward from the reference tread profile. By defining the tread of the middle land portion as described above, this tire mitigates the ground pressure acting on the longitudinal edges on both sides of the middle land portion, and is expected to improve fuel efficiency and braking performance on dry roads.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-111261

[0004] However, currently, in order to fully utilize the various performance characteristics of tires, tires with a specified orientation for installation on vehicles have been proposed. With such tires, if the tread of the land portion protrudes radially outward from the reference tread profile, as in the tire of Patent Document 1 mentioned above, there is a tendency for the land portion to experience uneven wear. Summary of the Invention

[0005] The present invention was made in view of the above problems, and its main objective is to improve the resistance to eccentric wear in tires with a specified orientation for installation on a vehicle.

[0006] This invention relates to a tire having a tread portion with a specified orientation for installation in a vehicle. The tread portion includes: a first tread end that becomes the inner side of the vehicle when installed; a second tread end that becomes the outer side of the vehicle when installed; a plurality of circumferential grooves extending continuously in the tire circumferential direction between the first tread end and the second tread end; and a plurality of land portions divided by the plurality of circumferential grooves, each land portion including: a crown land portion; a first intermediate land portion adjacent to the first tread end side of the crown land portion; and a second intermediate land portion adjacent to the second tread end side of the crown land portion. In a radial section including the tire's axis of rotation, under normal conditions where the tire is mounted on a normal rim with normal internal pressure and without load, the aforementioned crown land portion, the aforementioned first intermediate land portion, and the aforementioned second intermediate land portion each have a crown profile, a first intermediate profile, and a second intermediate profile that protrude radially outward from the reference tread profile. The maximum protrusion of the aforementioned crown profile from the reference tread profile is greater than the maximum protrusion of the aforementioned second intermediate profile from the reference tread profile, and the maximum protrusion of the aforementioned first intermediate profile from the reference tread profile is greater than the maximum protrusion of the aforementioned crown profile from the reference tread profile.

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

[0008] In the tire of the present invention, it is preferable that the maximum protrusion of the crown profile is 60% to 75% of the maximum protrusion of the first intermediate profile.

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

[0010] In the tire of the present invention, it is preferable that a plurality of transverse grooves extending along the tire axial direction are provided in the crown land portion, the first intermediate land portion and the second intermediate land portion respectively, and in each of the crown land portion, the first intermediate land portion and the second intermediate land portion, the number of pitches of the transverse grooves covering the entire circumference of the tire is 75 to 100.

[0011] In the tire of the present invention, preferably the plurality of circumferential grooves include: a first shoulder circumferential groove provided on the side closest to the first tread end; and a second shoulder circumferential groove provided on the side closest to the second tread end, wherein the maximum width of the second shoulder circumferential groove is smaller than the maximum width of the first shoulder circumferential groove.

[0012] In the tire of the present invention, it is preferable that the maximum groove width of the second shoulder circumferential groove is 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 a plurality of transverse grooves inclined at an angle of 10 to 30° relative to the tire axis are provided in the first intermediate land portion and the second intermediate land portion, respectively.

[0014] The tire of the present invention, by adopting the above-described structure, can improve its resistance to eccentric wear. Attached Figure Description

[0015] Figure 1 This is a unfolded view of the tread section of a tire according to one embodiment of the present invention.

[0016] Figure 2 yes Figure 1 Meridional sectional view of a tire.

[0017] Figure 3 yes Figure 2 Enlarged sectional views of the crown land portion, the first intermediate land portion, and the second intermediate land portion of the tire.

[0018] Figure 4 yes Figure 1 Enlarged view of the crown land portion, the first intermediate land portion, and the second intermediate land portion of the tire.

[0019] Figure 5 yes Figure 1 Enlarged view of the first shoulder land area.

[0020] Figure 6 yes Figure 2 Enlarged view of the second fetal shoulder land area.

[0021] Explanation of reference numerals in the attached figures

[0022] 2…tread portion; 3…circumferential groove; 9…land portion; 10…crown land portion; 11…first intermediate land portion; 12…second intermediate land portion; 44…reference tread profile; 45…crown profile; 46…first intermediate profile; 47…second intermediate profile; T1…first tread end; T2…second tread end. Detailed Implementation

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a developed view showing the tread portion 2 of a tire 1 according to one embodiment of the present invention. The tire 1 of this embodiment is suitable, for example, for use as a pneumatic tire for passenger vehicles used in winter. However, the present invention is not limited to this embodiment.

[0024] like Figure 1 As shown, the tire 1 of the present invention, for example, has a tread portion 2 that specifies the orientation for installation in a vehicle. The tread portion 2 includes a first tread end T1 that becomes the inner side of the vehicle when the tire 1 is installed in the vehicle, and a second tread end T2 that becomes the outer side of the vehicle when installed in the vehicle. The orientation for installation in the vehicle is indicated, for example, by text or symbols on the sidewall portion (illustration omitted).

[0025] The first tread end T1 and the second tread end T2 are the outermost contact points along the tire's axial direction when a normal load is applied to the tire 1 in its normal condition and it contacts the ground at a camber angle of 0°. Normal condition refers to the state where the tire is assembled on a normal rim, inflated to the normal internal pressure, and without load. In this specification, unless otherwise stated, the dimensions of various parts of the tire are values ​​measured under the aforementioned normal condition.

[0026] For tires with specified sizes, a "standard rim" refers to a rim that is specifically designed for each tire within a size system, including the tire's base specifications. For example, JATMA means "standard rim," TRA means "Design Rim," and ETRTO means "Measuring Rim." For tires without specified sizes, a "standard rim" means a rim that allows the tire to perform optimally; for example, using a rim recommended by the manufacturer.

[0027] For tires with specified sizes, "standard tire pressure" refers to the pressure specified for each tire within the specification system, including the tire's underlying specification. For JATMA, it's the "maximum pressure"; for TRA, it's the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and for ETRTO, it's "INFLATION PRESSURE". For tires without specified sizes, "standard rim pressure" means the tire pressure that allows it to perform optimally, for example, using the manufacturer's recommended pressure.

[0028] For tires with specified specifications, "standard load" refers to the load specified for each tire within the specification system, including the specifications on which the tire is based. For JATMA, it is "maximum load capacity"; for TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and for ETRTO, it is "LOAD CAPACITY". For tires without specified specifications, "standard load" refers to the load acting on a tire under its standard mounting condition. The aforementioned "standard mounting condition" refers to the state where the tire is mounted on a standard vehicle corresponding to its intended use, and is stationary on a flat road surface in a condition that allows the vehicle to travel.

[0029] The tread portion 2 includes a plurality of circumferential grooves 3 extending continuously along the tire circumference between the first tread end T1 and the second tread end T2, and a plurality of land portions 9 divided by the plurality of circumferential grooves 3.

[0030] 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 located on the side closest to the first tread end T1 among the multiple circumferential grooves 3. The second shoulder circumferential groove 7 is located on the side closest to the second tread end T2 among the multiple circumferential grooves 3. The first crown circumferential groove 4 is located between the first shoulder circumferential groove 6 and the tire equator C. The second crown circumferential groove 5 is located between the second shoulder circumferential groove 7 and the tire equator C.

[0031] The tire axial distance L1 from the tire equator C to the center line 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 tire axial distance L2 from the tire equator C to the center line 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 tire axial distance from the first tread end T1 to the second tread end T2 under the above-described normal condition.

[0032] In this embodiment, each circumferential groove 3 extends in a straight line along the tire circumference, or in a wavy shape with a slight amplitude along the center line of the groove.

[0033] The width W1 of each circumferential groove 3 is 3.0 mm or more, preferably 3.0% to 7.0% of the tread width TW. In this specification, the width of the circumferential groove 3 refers to the distance between the groove edges on both sides in the above-described normal state, in a direction orthogonal to the groove centerline. Furthermore, the groove edge is the boundary between the groove and the tread surface of the land portion in the above-described normal state.

[0034] The plurality of land portions 9 include a crown land portion 10, a first intermediate land portion 11, and a second intermediate land portion 12. In addition to these, the plurality of land portions 9 in this embodiment also include a first shoulder land portion 13 and a second shoulder land portion 14. The crown land portion 10 is divided between a first crown circumferential groove 4 and a second crown circumferential groove 5, and in this embodiment is disposed on the tire equator C. The first intermediate land portion 11 is adjacent to the first tread end 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 intermediate land portion 12 is adjacent to the second tread end 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.

[0035] The first shoulder land portion 13 is located on the outer side of the tire axial direction of the first shoulder circumferential groove 6 and includes the first tread end T1. The second shoulder land portion 14 is located on the outer side of the tire axial direction of the second shoulder circumferential groove 7 and includes the second tread end T2.

[0036] Figure 2 The diagram shows a meridional sectional view of the tire 1 of this embodiment in the aforementioned normal state. Figure 2 As shown, the tread portion 2 is formed by a curved profile that protrudes radially outward from the tire.

[0037] Figure 3 It shows Figure 2 Enlarged cross-sectional views of the crown land portion 10, the first intermediate land portion 11, and the second intermediate land portion 12. (See attached image.) Figure 3 As shown, the crown land portion 10, the first intermediate land portion 11, and the second intermediate land portion 12 each have a crown profile 45, a first intermediate profile 46, and a second intermediate profile 47 that protrude radially outward from the reference tread profile 44. Furthermore, in Figure 3 In order to facilitate understanding of the features of the invention, the curvature of each crown profile 45, the first intermediate profile 46 and the second intermediate profile 47 is shown in a manner that is greater than that of the actual object.

[0038] The aforementioned reference tread profile 44 at the first intermediate land portion 11 corresponds to an arc with a single radius of curvature passing through the edges of the circumferential grooves (in this embodiment, the first crown circumferential groove 4) adjacent to the inner side of the tire axial direction of the land portion 11 at both ends of the tread and the tire equator C side. The aforementioned reference tread profile 44 at the second intermediate land portion 12 is defined similarly.

[0039] The reference tread profile 44 at the land portion 10 of the tread corresponds to the arc with the larger radius of curvature among the first arc passing through the groove edge of the first tread end T1 side of the first circumferential groove 4 at both ends of the tread surface of the land portion 10 of the tread, and the second arc passing through the groove edge of the second tread end T2 side of the second circumferential groove 5 at both ends of the tread surface of the land portion 10 of the tread. In this embodiment, the first arc and the second arc are configured with the same radius of curvature.

[0040] In this invention, the maximum protrusion d3 of the crown profile 45 from the reference tread profile 44 is greater than the maximum protrusion d2 of the second intermediate profile 47 from the reference tread profile 44. Furthermore, the maximum protrusion d1 of the first intermediate profile 46 from the reference tread profile 44 is greater than the maximum protrusion d3 of the crown profile 45 from the reference tread profile 44. By employing the above-described structure, the tire 1 of this invention can improve its resistance to uneven wear. The following mechanism is hypothesized as a reason for this.

[0041] In this invention, by making the contour of each land portion 9 protrude beyond the reference tread contour 44, the ground pressure acting on the longitudinal edge of the land portion 9 can be mitigated, and the uneven wear near the longitudinal edge can be suppressed.

[0042] On the other hand, when the above-described profile is used in the tread portion 2, which is specified to be installed on the vehicle, there is a tendency for uneven wear to occur in the land portion (which corresponds to the first intermediate land portion 11 in this embodiment) that is slightly inside the vehicle than the tire equator. The reason for this is presumably that in a typical vehicle, due to the slight negative camber angle, the aforementioned land portion experiences a relatively large ground contact pressure.

[0043] In this invention, by setting the maximum protrusion of the contour of each land portion 9 to the aforementioned relationship, the ground pressure acting on the longitudinal edge of each land portion 9 can be evenly mitigated, and in particular, the uneven wear of the first intermediate land portion 11 is effectively suppressed. It is believed that the tire 1 of this invention can exhibit excellent resistance to uneven wear through this mechanism.

[0044] The structure of this embodiment will now be described in more detail. Furthermore, each structure described below represents a specific embodiment. Therefore, the present invention can achieve the aforementioned effects even without the structures described below. Additionally, even when any one of the structures described below is applied individually to the tire of the present invention possessing the above features, an improvement in the performance corresponding to each structure can be expected. Furthermore, when several structures of each of the structures described below are combined, an improvement in the combined performance corresponding to each structure can be expected.

[0045] like Figure 1 As shown, the maximum groove width W7 of the second tire shoulder groove 7 is preferably smaller than the maximum groove width W6 of the first tire shoulder groove 6. Specifically, the groove width W7 of the second tire shoulder groove 7 is 55% to 65% of the groove width W6 of the first tire shoulder groove 6. As a result, the air column resonance sound of the second tire shoulder groove 7, which has a significant impact on noise performance, is reduced.

[0046] like Figure 3 As shown, the maximum protrusion d3 of the crown profile 45, the maximum protrusion d1 of the first intermediate profile 46, and the maximum protrusion d2 of the second intermediate profile are all less than 0.15 mm. This suppresses uneven wear on the central portion of the tire's axial direction in the land section.

[0047] The maximum protrusion d3 of the crown profile 45 is preferably 60% to 75% of the maximum protrusion d1 of the first intermediate profile 46. Furthermore, the maximum protrusion d2 of the second intermediate profile 47 is preferably 25% to 40% of the maximum protrusion d1 of the first intermediate profile 46. This results in a more uniform ground pressure acting on each land segment, suppressing uneven wear.

[0048] Figure 4 Enlarged views of the tire crown land portion 10, the first intermediate land portion 11, and the second intermediate land portion 12 are shown. Figure 4 As shown, transverse grooves extending along the tire axial direction are provided in the crown land portion 10, the first intermediate land portion 11, and the second intermediate land portion 12. In each of the crown land portion 10, the first intermediate land portion 11, and the second intermediate land portion 12, the number of pitches of the transverse grooves covering the entire circumference of the tire is, for example, 75 to 100, preferably 80 to 90. As a result, the resistance to uneven wear and noise performance are improved in a balanced manner.

[0049] A plurality of tread grooves 15 are provided on the land portion 10 of the tread. The tread grooves 15 are inclined relative to the tire axial direction in a first direction (lower right in the figures of this specification) and completely cross the land portion 10 of the tread along the tire axial direction.

[0050] Additionally, the tread groove 15 includes a first end 16 and a second end 17 along the tire axial direction, and a central portion 18 disposed between the first end 16 and the second end 17. The width of the central portion 18 of the tread groove 15 is smaller than the width of the groove at the first end 16 and the second end 17.

[0051] The maximum width of the central portion 18 of the tread groove 15 is, for example, less than 15% of the maximum width of the first end 16 and the second end 17, preferably 3% to 15%. As a further preferred embodiment, the central portion 18 of the tread groove 15 in this embodiment is configured as a narrow groove with a width of 1.5 mm or less. This maintains the rigidity of the tread land portion 10 and improves handling stability (hereinafter, sometimes simply referred to as "handling stability") on dry roads. Hereinafter, unless otherwise stated, "narrow groove" refers to a portion of the groove with a width of 1.5 mm or less. "Narrow groove" refers to a groove with a width of 1.5 mm or less throughout. Grooves not marked as narrow grooves have a width greater than 1.5 mm. In each tread groove of this embodiment, the portion not marked as a narrow groove has a width of, for example, 2.0 to 4.0 mm.

[0052] The central portion 18 is located at the center of the tire axial direction, for example, across the land portion 10 of the tread. The axial length L3 of the central portion 18 is, for example, 40% to 60% of the axial width W2 of the land portion 10 of the tread. This central portion 18 improves both snow performance and noise performance in a balanced way.

[0053] The central portion 18 is inclined in the first direction relative to the tire axis. The angle θ2 of the central portion 18 relative to the tire axis is, for example, 45° or less, preferably 35 to 45°.

[0054] The axial length of the tire at the first end 16 and the axial length of the tire at the second end 17 are smaller than the axial length L3 of the tire at the central part 18, and are set to be 20% to 30% of the axial width W2 of the tire crown land part 10.

[0055] The first end portion 16 and the second end portion 17 are inclined relative to the tire axial direction in the first direction. Furthermore, the angles of the first end portion 16 and the second end portion 17 relative to the tire axial direction are smaller than the angle of the central portion 18 relative to the tire axial direction, for example, 10 to 25°. Therefore, the tread groove 15 preferably includes: a portion formed by the first end portion 16 and the central portion 18 that slightly protrudes to one side in the tire circumferential direction, and a portion formed by the second end portion 17 and the central portion 18 that slightly protrudes to the other side in the tire circumferential direction. The first end portion 16 and the second end portion 17 of such a tread groove 15, together with the circumferential groove, form a strong snow column, which improves traction performance on snow.

[0056] By giving the tread groove 15 the structure described above, the angle of the straight line connecting the two ends of the tread groove 15 with respect to the tire axis is, for example, 45° or less, preferably 20 to 40°.

[0057] The circumferential pitch length P1 of the multiple tread grooves 15 is, for example, 60% to 90% of the axial width W2 of the tread land portion 10. As a result, snow performance and noise performance are improved in a balanced manner.

[0058] A first crown groove 23 and a second crown groove 24 are provided between two adjacent crown grooves 15 in the circumferential direction of the tire. The first crown groove 23 extends from the circumference of the first crown towards groove 4 and is interrupted within the crown land portion 10. The second crown groove 24 extends from the circumference of the second crown towards groove 5 and is interrupted within the crown land portion 10.

[0059] The axial length of the first crown groove 23 is, for example, 80% to 120% of the axial length of the first end 16 of the crown transverse groove 15. Furthermore, the second crown groove 24 is interrupted, for example, at a position closer to the first crown circumferential groove 4 than the second end 17 of the crown transverse groove 15. Such first crown grooves 23 and second crown grooves 24 disperse the frequency of noise when the crown land portion 10 touches the ground, thereby improving noise performance.

[0060] The first crown groove 23 and the second crown groove 24 are inclined in a first direction relative to the tire axial direction. The angles of the first crown groove 23 and the second crown groove 24 relative to the tire axial direction are smaller than the angle of the central portion 18 of the crown lateral groove 15 relative to the tire axial direction. On the other hand, the angle difference between the first crown groove 23 and the second crown groove 24 and the aforementioned central portion 18 is, for example, 15° or less, preferably 10° or less. Specifically, the first crown groove 23 and the second crown groove 24 are inclined at an angle of 30 to 40° relative to the tire axial direction.

[0061] A plurality of first intermediate transverse grooves 20 are provided in the first intermediate land portion 11. The first intermediate transverse grooves 20 are inclined relative to the tire axis in a second direction opposite to the first direction (in the figures of this specification, they are in the upper right direction), and completely transversely cut through the first intermediate land portion 11 along the tire axis.

[0062] The first intermediate lateral groove 20 is configured at a different angle relative to the tire axial direction than the crown groove 15. This reliably prevents resonance caused by noise generated by the various grooves. The angle of the first intermediate lateral groove 20 relative to the tire axial direction is, for example, 10–30°. Such a first intermediate lateral groove 20 helps to further improve noise performance.

[0063] In this embodiment, by making the tread lateral groove 15 and the first intermediate lateral groove 20 adjacent to each other along the tire axial direction, when viewed from above, the straight line connecting the two ends of the tread lateral groove 15 intersects the straight line connecting the two ends of the first intermediate lateral groove 20 within the first circumferential tread groove 4. In a more preferred embodiment, the area obtained by projecting the connection between the tread lateral groove 15 and the first circumferential tread groove 4 parallel to the tire axial direction overlaps with the connection between the first intermediate lateral groove 20 and the first circumferential tread groove 4. Therefore, the tread lateral groove 15 and the first intermediate lateral groove 20 can form a solid snow column at the connection between themselves and the first circumferential tread groove 4, thereby achieving excellent snow performance.

[0064] In this embodiment, the first intermediate land portion 11 is provided with a plurality of first intermediate grooves 26. The first intermediate grooves 26 completely bisect the first intermediate land portion 11 along the tire axis and are alternately provided with the first intermediate transverse grooves 20 along the tire circumference.

[0065] The first intermediate groove 26 is inclined, for example, in the second direction relative to the tire axial direction. In this embodiment, the first intermediate groove 26 extends along the first intermediate transverse groove 20, and the angle difference between them is 5° or less. In addition, the first intermediate groove 26 is arranged at an angle smaller than that of the first crown groove 23 and the second crown groove 24 relative to the tire axial direction. Specifically, the angle of the first intermediate groove 26 relative to the tire axial direction is 10 to 30°.

[0066] In the second intermediate land portion 12, a plurality of second intermediate transverse grooves 30 and second intermediate fine grooves 31 are alternately provided along the tire circumference.

[0067] The second intermediate lateral groove 30 is inclined in a second direction relative to the tire axial direction, and completely transverses the second intermediate land portion 12 along the tire axial direction. The second intermediate lateral groove 30 is preferably positioned relative to the tire axial direction at a distance greater than the central portion 18 of the crown groove 15 (e.g., Figure 2 (As shown) a small angle configuration. The angle of the second intermediate lateral groove 30 relative to the tire axial direction is, for example, 10 to 30°. As a result, resonance of noise generated by the second intermediate lateral groove 30 and the crown lateral groove 15 can be suppressed.

[0068] The second intermediate transverse groove 30 includes, for example, an inner groove portion 30a extending from the second crown circumferential groove 5, and an outer fine groove portion 30b extending from the outer end of the inner groove portion 30a to the second shoulder circumferential groove 7.

[0069] The inner groove 30a, for example, intersects the center position of the tire axial direction of the second intermediate land portion 12. The tire axial length L4 of the inner groove 30a is, for example, 60% to 90% of the tire axial width W3 of the second intermediate land portion 12. Such an inner groove 30a improves snow performance and resistance to eccentric wear in a balanced way.

[0070] In this embodiment, it is preferable that the projected area obtained by extending the inner groove 30a along its length direction overlaps with the connecting portion of the second circumferential groove 5 and the transverse groove 15 of the tire crown. As a result, snow performance is further improved.

[0071] The outer groove 30b extends in a straight line from the inner groove 30a to the second shoulder groove 7 in a second direction.

[0072] The second intermediate groove 31, for example, is inclined in the second direction relative to the tire axis and completely bisects the second intermediate land portion 12 along the tire axis. In this embodiment, the second intermediate groove 31 extends along the second intermediate transverse groove 30, for example, and their angle difference is less than 5°. Such a second intermediate groove 31 can improve snow performance while suppressing uneven wear of the second intermediate land portion 12.

[0073] Figure 5 An enlarged view of the first tire shoulder land portion 13 is shown. (See attached image.) Figure 5 As shown, on the first shoulder land portion 13, a first shoulder transverse groove 35 and a first shoulder fine groove 36 are alternately provided along the tire circumference.

[0074] The first shoulder lateral groove 35 extends, for example, at least from the first tread end T1 to the first shoulder circumferential groove 6. The first shoulder lateral groove 35 curves, for example, protruding to one side of the tire circumferentially.

[0075] The first shoulder lateral groove 35 includes, for example, a main body portion 35a on the side of the first tread end T1, and an inner end portion 35b extending from the inner end of the main body portion 35a in the tire axial direction to the inner end portion 35b of the first shoulder circumferential groove 6.

[0076] The main body 35a of the first shoulder lateral groove 35 is, for example, transversely intersecting the center position of the tire axial direction of the first shoulder land portion 13. The tire axial length L5 of the main body 35a is, for example, 60% to 80% of the tire axial width W4 of the first shoulder land portion 13. As a result, snow performance and noise performance are improved in a balanced way.

[0077] The inner end portion 35b of the first shoulder transverse groove 35 has a groove width smaller than that of the main body portion 35a. The groove width of the inner end portion 35b is preferably 3% to 15% of the groove width of the main body portion 35a. In this embodiment, the inner end portion 35b of the first shoulder transverse groove 35 is configured as a narrow groove with a groove width of 1.5 mm or less. This reduces the amount of air passing through the first shoulder transverse groove 35, thus improving noise performance.

[0078] The tire axial length L6 of the inner end 35b of the first shoulder groove 35 is preferably longer than the tire axial length L3 of the central portion 18 of the crown groove 15 (e.g., Figure 4(As shown) Small. Specifically, the length L6 of the inner end portion 35b is 40% to 60% of the length L3 of the central portion 18. As a result, the resonance of noise generated by the crown groove 15 and the first shoulder groove 35 can be suppressed.

[0079] The first shoulder groove 36, for example, completely bisects the first shoulder land portion 13 along the tire axial direction. In this embodiment, the first shoulder groove 36 is curved in a manner that protrudes to one side in the tire circumferential direction. In a further preferred embodiment, the first shoulder groove 36 and the first shoulder transverse groove 35 extend along each other, and their angle difference is less than 5°. Such a first shoulder groove 36 can improve snow performance while suppressing uneven wear of the first shoulder land portion 13.

[0080] Figure 6 An enlarged view of the second shoulder land portion 14 is shown. (See attached image.) Figure 6 As shown, on the land portion 14 of the second shoulder, a second shoulder transverse groove 40 and a second shoulder fine groove 41 are alternately provided along the tire circumference.

[0081] The second shoulder lateral groove 40 extends, for example, at least from the second tread end T2 toward the axial inner side of the tire and is interrupted within the second shoulder land portion 14. The axial length L7 of the second shoulder lateral groove 40 is, for example, 75% to 90% of the axial width W5 of the second shoulder land portion 14. This prevents air from escaping from the second shoulder circumferential groove 7 toward the second tread end T2 side, thus suppressing noise performance degradation.

[0082] The second shoulder lateral groove 40 includes, for example, a main body portion 40a on the second tread end T2 side and an inner end portion 40b connected to the inner side of the tire axial direction of the main body portion 40a and having a groove width smaller than that of the main body portion 40a.

[0083] The main body 40a of the second shoulder lateral groove 40, for example, intersects the center position of the tire axial direction of the second shoulder land portion 14. The tire axial length L8 of the main body 40a is, for example, 60% to 70% of the tire axial width W5 of the second shoulder land portion 14. As a result, snow performance and noise performance are improved in a balanced way.

[0084] The inner end portion 40b of the second shoulder lateral groove 40 extends from the main body portion 40a and is interrupted within the second shoulder land portion 14. The tire axial length L9 of the inner end portion 40b is, for example, 15% to 25% of the tire axial width W5 of the second shoulder land portion 14. In a further preferred embodiment, the length L9 of the inner end portion 40b is smaller than the tire axial length L3 of the central portion 18 of the crown lateral groove 15. This suppresses resonance of noise generated by each lateral groove.

[0085] The groove width of the inner end portion 40b of the second shoulder transverse groove 40 is preferably 3% to 15% of the groove width of the main body portion 40a of the second shoulder transverse groove 40. In this embodiment, the inner end portion 40b of the second shoulder transverse groove 40 is configured as a narrow groove with a groove width of 1.5 mm or less. As a result, excellent handling stability is obtained.

[0086] The second shoulder groove 41, for example, completely bisects the second shoulder land portion 14 along the tire axial direction. In this embodiment, the second shoulder groove 41 and the second shoulder transverse groove 40 extend along each other, and their angular difference is less than 5°.

[0087] The tire according to one embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment described above, and can be implemented in various ways.

[0088]

Example

[0089] Based on the specifications in Table 1, a prototype with... Figure 1 The tire has a basic tread size of 225 / 65R17. As a comparative example, a tire with the same maximum protrusion of the crown land portion, the first intermediate land portion, and the second intermediate land portion was prototyped. The comparative example tire, except for the aforementioned aspects, is similar to... Figure 1 The tires shown are actually identical. The uneven wear resistance and noise performance of each test tire were tested. The common specifications and test methods for all test tires are as follows.

[0090] Wheel rim installation: 17×7.0J

[0091] Tire internal pressure: 230 kPa for front tires and 210 kPa for rear tires

[0092] Test vehicle: 1600cc engine, front-wheel drive

[0093] Tire mounting location: All wheels

[0094] <Resistance to eccentric wear>

[0095] After the test vehicle traveled a certain distance, the wear condition of the tire tread (especially the wear condition around the first intermediate land area) was visually evaluated. The results were expressed as a score of 100 for the wear condition of the comparative example; the higher the score, the better the resistance to uneven wear.

[0096] <Noise Performance>

[0097] The noise performance of the tested vehicles on dry roads was evaluated by the drivers' senses. The results are expressed as an index with the noise performance of the comparative examples set at 100; the higher the value, the better the noise performance.

[0098] The test results are shown in Table 1.

[0099] [Table 1]

[0100]

[0101] The test results confirmed that the tire of the embodiment exhibited excellent resistance to uneven wear. Furthermore, the tire of the embodiment also demonstrated excellent noise performance.

Claims

1. A tire having a tread pattern specifying an orientation for mounting on a vehicle, wherein, The tread portion includes: a first tread end that becomes the inner side of the vehicle when mounted on the vehicle; a second tread end that becomes the outer side of the vehicle when mounted on the vehicle; a plurality of circumferential grooves extending continuously in the tire circumferential direction between the first tread end and the second tread end; and a plurality of land portions divided by the plurality of circumferential grooves. The plurality of land portions include: a crown land portion; a first intermediate land portion adjacent to the first tread end side of the crown land portion; a first shoulder land portion adjacent to the first tread end side of the first intermediate land portion and including the first tread end; a second intermediate land portion adjacent to the second tread end side of the crown land portion; and a second shoulder land portion adjacent to the second tread end side of the second intermediate land portion and including the second tread end. In a normal, unloaded state, within a radial cross-section including the tire's axis of rotation, the crown land portion, the first intermediate land portion, and the second intermediate land portion each have a crown profile, a first intermediate profile, and a second intermediate profile that protrude radially outward from the reference tread profile. The maximum protrusion of the crown profile from the reference tread profile is greater than the maximum protrusion of the second intermediate profile from the reference tread profile. The maximum protrusion of the first intermediate profile from the reference tread profile is greater than the maximum protrusion of the crown profile from the reference tread profile. A second shoulder lateral groove is provided in the second shoulder land portion, extending at least from the second tread end toward the axial inward side of the tire and interrupted within the second shoulder land portion. The second shoulder lateral groove includes a main body portion on the end side of the second tread and an inner end portion that is connected to the inner side of the main body portion along the tire axial direction and has a groove width smaller than that of the main body portion. The land portion of the tire crown has a first end and a second end along the tire axial direction, and a lateral groove in the center portion disposed between the first end and the second end. The lateral grooves of the tire crown are inclined in a first direction relative to the tire axial direction and completely bisect the land portion of the tire crown along the tire axial direction. The width of the central portion of the transverse groove of the tread is smaller than the width of the groove at the first end and the width of the groove at the second end. The tire axial length L9 at the inner end of the second shoulder groove is less than the tire axial length L3 at the central part of the crown groove.

2. The tire according to claim 1, wherein, The maximum protrusion of each of the crown contour, the first intermediate contour, and the second intermediate contour is less than 0.15 mm.

3. The tire according to claim 1 or 2, wherein, The maximum protrusion of the crown profile is 60% to 75% of the maximum protrusion of the first intermediate profile.

4. The tire according to claim 1 or 2, wherein, The maximum protrusion of the second intermediate contour is 25% to 40% of the maximum protrusion of the first intermediate contour.

5. The tire according to claim 1 or 2, wherein, Multiple transverse grooves extending along the tire axial direction are respectively provided on the land portion of the tread, the first intermediate land portion, and the second intermediate land portion. In each of the crown land portion, the first intermediate land portion, and the second intermediate land portion, the number of pitches of the lateral grooves covering the entire circumference of the tire is 75 to 100.

6. The tire according to claim 1 or 2, wherein, The plurality of circumferential grooves include: a first shoulder circumferential groove located on the side closest to the first tread end; and a second shoulder circumferential groove located on the side closest to the second tread end. The maximum width of the second shoulder groove is smaller than the maximum width of the first shoulder groove.

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

8. The tire according to any one of claims 1, 2, and 7, wherein, The first intermediate land portion and the second intermediate land portion are respectively provided with a plurality of transverse grooves inclined at an angle of 10 to 30° relative to the tire axis.

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