tire

Abstract

To provide a tire in which the steering stability on a dry road surface is improved.SOLUTION: A tire includes a tread portion 2 whose direction of attachment to a vehicle is designated. A land portion 4 of the tread portion 2 includes a crown land portion 13, a first middle land portion 12, and a second middle land portion 14. Under a 50% loaded condition of being rim-assembled to a normal rim at a normal inner pressure, loaded with 50% of the normal load, and grounded to the planar surface at a camber angle 0°, when widths of the ground contact surfaces in the tire axial direction of the first middle land portion 12, the crown land portion 13, and the second middle land portion 14 are respectively W1m, Wc, and W2m, the following formula (1) is satisfied, When the widths in the tire axial direction of an outer ground contact surface 36 and an inner ground contact surface 37 of the crown land portion 13 are respectively Wco and Wci, the following formula (2) is satisfied, W1m>Wc>W2m...(1). Wco>Wci...(2).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to tires. [Background technology]

[0002] Patent Document 1 below proposes a pneumatic tire whose tread is divided into a crown land portion and a pair of middle land portions. The crown land portion and the middle land portion are each formed as ribs that extend continuously in the tire circumferential direction. This feature of the pneumatic tire reduces noise during driving. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-132181 Summary of the Invention [Problem to be solved by the invention]

[0004] The crown land portion and middle land portion of a tire are subjected to high ground contact pressure not only when driving straight but also when cornering, and therefore contribute greatly to steering stability on dry roads. The developers discovered that the above performance could be further improved by reviewing the configuration of these land portions, leading to the completion of this disclosure.

[0005] The present disclosure has been made in consideration of the above problems, and has as its main object to provide a tire with improved steering stability on dry road surfaces. [Means for solving the problem]

[0006] The present disclosure relates to a tire having a tread portion whose orientation when mounted on a vehicle is specified, the tread portion including a first tread edge that is on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is on the inner side 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 by the circumferential grooves, the plurality of land portions including a crown land portion disposed on the tire equator, 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 is mounted on a regular rim. When the tire is mounted to a rim at normal internal pressure and is subjected to a load of 50% of the normal load with the tire in contact with a flat surface at a camber angle of 0°, and when the tire is in a 50% load state, the tire satisfies the following formula (1) when the axial widths of the contact surfaces of the first middle land portion, the crown land portion, and the second middle land portion are W1m, Wc, and W2m, respectively; the crown land portion includes an outer contact surface closer to the first tread edge than the tire equator, and an inner contact surface closer to the second tread edge than the tire equator; and when the axial widths of the outer contact surface and the inner contact surface are Wco and Wci, respectively, the tire satisfies the following formula (2). W1m>Wc>W2m…(1) Wco>Wci…(2) [Effects of the Invention]

[0007] By adopting the above-described configuration, the tire of the present disclosure can improve steering stability on dry road surfaces. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a development view of a tread portion showing an embodiment of the present disclosure. FIG. [Figure 2] FIG. 2 is an enlarged view showing the shape of the contact patch of the tread portion when in contact with the ground. [Figure 3] FIG. 2 is an enlarged view of a first shoulder land portion and a first middle land portion of FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 4 is a cross-sectional view taken along line CC in FIG. [Figure 6] FIG. 4 is a cross-sectional view taken along line BB in FIG. 3. [Figure 7] FIG. 4 is a cross-sectional view taken along line DD in FIG. 3. [Figure 8] 2 is an enlarged view of a first middle land portion, a crown land portion, and a second middle land portion of FIG. 1. FIG. [Figure 9] FIG. 2 is an enlarged view of the second shoulder land portion of FIG. 1. [Figure 10] FIG. 10 is a cross-sectional view taken along the line EE in FIG. 9. [Figure 11] FIG. 2 is a cross-sectional view taken along the line FF in FIG. 1. [Figure 12] FIG. 2 is a cross-sectional view taken along line GG in FIG. 1. [Figure 13] FIG. 10 is an enlarged view of a first middle land portion according to another embodiment. [Figure 14] FIG. 10 is an enlarged view of a first middle land portion according to another embodiment. [Figure 15] FIG. 4 is a development view of a tread portion of another embodiment of the present disclosure. [Figure 16] FIG. 16 is an enlarged view of the first middle land portion of FIG. [Figure 17] FIG. 17 is a cross-sectional view taken along line HH in FIG. 16. [Figure 18] FIG. 10 is an enlarged view of a first middle land portion according to another embodiment. [Figure 19] FIG. 2 is a development view of a tread portion of a reference tire. [Figure 20] FIG. 2 is a development view of a tread portion of a tire of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present disclosure will be described below with reference to the drawings. Fig. 1 is a development view of a tread portion 2 of a tire 1 showing an embodiment of the present disclosure. The tire 1 of this embodiment is suitably used, for example, as a pneumatic tire for passenger cars. However, the present disclosure is not limited to such an embodiment and may also be applied to pneumatic tires for heavy loads and non-pneumatic tires that are not filled with pressurized air inside the tire.

[0010] 1, a tire 1 of the present disclosure has a tread portion 2 whose mounting orientation on a vehicle is specified. The tread portion 2 has a first tread edge T1 intended to be located on the outer side of the vehicle when the tire 1 is mounted on the vehicle, and a second tread edge T2 intended to be located on the inner side 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 the sidewall portion (not shown).

[0011] The first tread edge T1 and the second tread edge T2 each correspond to the axially outermost contact points when the tire 1 in a normal state is loaded with 50% of the normal load and contacts the ground on a flat surface with a camber angle of 0°.

[0012] "Normal condition" means, in the case of a pneumatic tire for which various standards are established, that the tire is mounted on a normal rim, inflated to the normal internal pressure, and is in an unloaded state. In the case of a tire for which various standards are not established or a non-pneumatic tire, the normal condition means a standard use state according to the intended use of the tire, in which the tire is not mounted on a vehicle and is unloaded. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal condition.

[0013] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "design rim," and in the case of ETRTO, it is called a "measuring rim."

[0014] "Normal internal pressure" is the air pressure specified for each tire by each standard in the standard system, including the standard on which the tire 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."

[0015] For pneumatic tires for which various standards are established, the "normal load" refers to the load specified for each tire in the standard system, including the standard on which the tire is based. For example, in the case of JATMA, it is the "maximum load capacity," in the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and in the case of ETRTO, it is the "LOAD CAPACITY." For tires for which various standards are not established or non-pneumatic tires, the "normal load" refers to the load acting on a single tire in its standard mounted state. The "standard mounted state" refers to the 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 in a drivable state.

[0016] The tread portion 2 has a plurality of circumferential grooves 3 extending continuously in the tire circumferential direction between the first tread edge T1 and the second tread edge T2, and a plurality of land portions 4 divided by the circumferential grooves. The tire 1 of this embodiment is configured as a so-called five-rib tire in which the tread portion 2 includes five land portions 4 divided by four circumferential grooves 3.

[0017] The circumferential grooves 3 include, for example, a first shoulder circumferential groove 5, a second shoulder circumferential groove 8, a first crown circumferential groove 6, and a second crown circumferential groove 7. The first shoulder circumferential groove 5 is provided between a first tread edge T1 and the tire equator C. The second shoulder circumferential groove 8 is provided between a second tread edge T2 and the tire equator C. The first crown circumferential groove 6 is provided between the first shoulder circumferential groove 5 and the tire equator C. The second crown circumferential groove 7 is provided between the second shoulder circumferential groove 8 and the tire equator C.

[0018] The axial distance L1 from the tire equator C to the groove center line of the first shoulder circumferential groove 5 or the second shoulder circumferential groove 8 is preferably, for example, 25% to 35% of the tread width TW. The axial distance L2 from the tire equator C to the groove center line of the first crown circumferential groove 6 or the second crown circumferential groove 7 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.

[0019] Each circumferential groove 3 of this embodiment extends, for example, linearly in parallel to the tire circumferential direction. Each circumferential groove 3 may extend, for example, in a wavy shape.

[0020] The groove width W1 of each circumferential groove 3 is preferably, for example, 2.0% to 8.0% of the tread width TW. In this embodiment, the first shoulder circumferential groove 5 has the smallest groove width among the four circumferential grooves 3. However, the present disclosure is not limited to this embodiment. In the case of a pneumatic tire for a passenger car, the depth of each circumferential groove 3 is preferably, for example, 5 to 10 mm.

[0021] The land portion 4 of the present disclosure includes a crown land portion 13, a first middle land portion 12, and a second middle land portion 14. The crown land portion 13 is disposed on the tire equator C and is divided between the first crown circumferential groove 6 and the second crown circumferential groove 7. The first middle land portion 12 is adjacent to the crown land portion 13 on the first tread edge T1 side and is divided into the first shoulder circumferential groove 5 and the first crown circumferential groove 6. The second middle land portion 14 is adjacent to the crown land portion 13 on the second tread edge T2 side and is divided into the second shoulder circumferential groove 8 and the second crown circumferential groove 7.

[0022] The land portion 4 of this embodiment further includes a first shoulder land portion 11 and a second shoulder land portion 15. The first shoulder land portion 11 includes the first tread edge T1 and is adjacent to the first tread edge T1 side of the first middle land portion 12. The second shoulder land portion 15 includes the second tread edge T2 and is adjacent to the second middle land portion 14 on the second tread edge T2 side.

[0023] Figure 2 shows an enlarged view of the contact patch shape of the tread portion 2 when the tire is in contact with the ground. As shown in Figure 2, when the tire is mounted to a regular rim with a regular internal pressure, and is in a 50% load state with 50% of the regular load applied and the tire in contact with the ground flatly at a camber angle of 0°, the widths of the contact patches in the axial direction of the first shoulder land portion 11, the first middle land portion 12, the crown land portion 13, the second middle land portion 14, and the second shoulder land portion 15 are W1s, W1m, Wc, W2m, and W2s, respectively, and the following formula (1) is satisfied. W1m>Wc>W2m…(1)

[0024] 1, the crown land portion 13 includes an outer contact surface 36 located closer to the first tread edge T1 than the tire equator C, and an inner contact surface 37 located closer to the second tread edge than the tire equator C. In the present disclosure, when the axial widths of the outer contact surface 36 and the inner contact surface 37 are Wco and Wci, respectively, the following formula (2) is satisfied. Wco>Wci…(2)

[0025] By adopting the above configuration, the present disclosure can improve steering stability on dry roads while ensuring various tire performances, including wet performance. The following mechanism is presumed to be the reason for this.

[0026] With the above configuration, the tire 1 of the present disclosure has an increased rigidity of each land portion of the tread portion 2 toward the outer side of the vehicle, which causes the cornering force to increase linearly with an increase in the steering angle, improving steering stability on dry roads. In particular, the crown land portion 13 satisfies the above formula (2), so the above effect is reliably achieved. It is presumed that the tire of the present disclosure can improve steering stability on dry roads through the above mechanism.

[0027] The following describes the configuration of this embodiment in more detail. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that the present disclosure can achieve the above-described effects even if it does not include the configurations described below. Furthermore, even if any one of the configurations described below is applied alone to a tire of the present disclosure having the above-described characteristics, performance improvement corresponding to each configuration can be expected. Furthermore, when several of the configurations described below are applied in combination, combined performance improvement corresponding to each configuration can be expected.

[0028] It is desirable that the tire 1 of this embodiment satisfies the following formula (3) under a 50% load condition. In such a tire 1, the land portion close to the first tread edge T1 has greater rigidity. Therefore, even when the center of the contact patch moves toward the first tread edge T1 due to steering, the steering response is stable and cornering force is generated linearly with increasing steering angle. Therefore, the tire 1 of this embodiment can further improve handling stability on dry road surfaces (hereinafter sometimes simply referred to as "handling stability"). W1s>W1m>Wc>W2m≧W2s …(3)

[0029] Under a 50% load condition, the axial width W1s of the ground contact surface of the first shoulder land portion 11 is preferably 115% to 125% of the axial width Wc of the ground contact surface of the crown land portion 13. This optimizes the rigidity of the first shoulder land portion 11, and in addition to the above-mentioned effects, noise performance can also be improved.

[0030] From the same viewpoint, it is desirable that the axial width W1m of the ground contact surface of the first middle land portion 12 is 101% to 107% of the axial width Wc of the ground contact surface of the crown land portion 13 under a 50% load condition.

[0031] Under a 50% load condition, the axial width W2m of the ground contact surface of the second middle land portion 14 is preferably 90% to 99% of the axial width Wc of the ground contact surface of the crown land portion 13. This improves noise performance when traveling straight. It also reduces the transmission of tire vibrations to the vehicle body when traveling straight, improving ride comfort.

[0032] From the same viewpoint, it is desirable that the axial width W2s of the ground contact surface of the second shoulder land portion 15 is 90% to 99% of the axial width Wc of the ground contact surface of the crown land portion 13 under a 50% load condition.

[0033] As a more preferable aspect, in this embodiment, under a 50% load condition, the width W2m of the second middle land portion 14 is set to be the same as the width W2s of the second shoulder land portion 15. This makes the progression of wear between the second middle land portion 14 and the second shoulder land portion 15 uniform, improving uneven wear resistance.

[0034] As shown in FIG. 1 , each land portion 4 of the embodiment is provided with a sipe 16. In this specification, a "sipe" refers to a cut element having a small width, where the width between two sipe walls in the main body of the sipe 16 is 1.5 mm or less. The width of the sipe 16 is preferably 0.2 to 1.2 mm, and more preferably 0.5 to 1.0 mm. The sipe 16 may include a widened portion that opens with a width greater than the width, or a flask bottom that is wider than the width.

[0035] Fig. 3 shows an enlarged view of the first shoulder land portion 11 and the first middle land portion 12. As shown in Fig. 3, the first shoulder land portion 11 is provided with only sipes, which increases the rigidity of the first shoulder land portion 11. In this embodiment, the first shoulder land portion 11 is provided with a plurality of first shoulder sipes 21 extending in the tire axial direction.

[0036] The circumferential pitch length P1 of the first shoulder sipes 21 is, for example, 100% to 130% of the axial tread width W3 of the first shoulder land portion 11. The circumferential pitch length of two sipes is the distance parallel to the circumferential direction of the tire from the center position in the width direction of one sipe in a cross section to the center position of the other sipe. If the distance varies in the axial direction of the tire, the intermediate distance corresponds to the circumferential pitch length.

[0037] It is desirable that the first shoulder sipes 21 communicate with at least the first shoulder circumferential groove 5. In this embodiment, the first shoulder sipes 21 extend, for example, from the first shoulder circumferential groove 5 to the first tread edge T1 and completely cross the tread surface of the first shoulder land portion 11. However, the first shoulder sipes 21 are not limited to this form, and may have an interrupted end within the first shoulder land portion 11.

[0038] The first shoulder sipes 21 are inclined, for example, in a first direction (inclined upward to the right in each drawing of this specification) with respect to the tire axial direction. The angle of the first shoulder sipes 21 with respect to the tire axial direction is, for example, 5 to 35 degrees. In a more desirable embodiment, the first shoulder sipes 21 include a portion where the angle with respect to the tire axial direction increases toward the second tread edge T2. Such first shoulder sipes 21 can also exert frictional force in the tire axial direction.

[0039] The opening width W4 of the first shoulder sipes 21 at the tread surface is larger than the opening width W5 of the first middle sipes 30 at the tread surface, for example. Specifically, the opening width W4 of the first shoulder sipes 21 is, for example, 4.0 to 8.0 mm. The opening width W5 of the first middle sipes 30 is, for example, 2.0 to 6.0 mm. Furthermore, the opening width W5 of the first middle sipes 30 is 50% to 90% of the opening width W4 of the first shoulder sipes 21. Such first shoulder sipes 21 and first middle sipes 30 can improve uneven wear resistance.

[0040] Fig. 4 shows a cross section of the first shoulder sipe 21 taken along line AA in Fig. 3. As shown in Fig. 4, the first shoulder sipe 21 includes a main body portion 21a extending in the tire radial direction and a widened portion 21b that opens at the tread surface of the land portion and has a width greater than that of the main body portion 21a. In this embodiment, the width of the main body portion is, for example, 0.5 to 1.5 mm.

[0041] The widened portion 21b of the first shoulder sipe 21 includes an inclined surface 22 extending from the main body portion 21a to the tread surface. In this embodiment, the inclined surface 22 is flat and inclined at an angle θ1 of 50 to 70° relative to the tire radial direction. This widened portion 21b allows the entire inclined surface 22 to come into contact with the ground when a large ground pressure acts on the land portion, thereby reliably expanding the effective contact area of ​​the tread portion. This further improves steering stability.

[0042] The depth d1 of the widened portion 21b of the first shoulder sipe 21 is 10% to 30% of the maximum depth d3 of the first shoulder sipe 21, and in a desirable embodiment, is 0.5 to 2.0 mm. The maximum depth d3 of the first shoulder sipe 21 is, for example, 70% to 100% of the depth of the circumferential groove 3.

[0043] The width W6 of the widened portion 21b of the first shoulder sipe 21 (the width along the tread surface in the cross section of the sipe) is, for example, 2.0 to 4.0 mm.

[0044] FIG. 5 shows a cross-sectional view taken along line CC in FIG. 3. As shown in FIG. 5, the first shoulder sipe 21 includes a shallow bottom portion 23 whose bottom portion is locally raised. The shallow bottom portion 23 in this embodiment is provided, for example, at the connecting portion with the first shoulder circumferential groove 5. The minimum depth d4 of the shallow bottom portion 23 of the first shoulder sipe 21 is 40% to 60% of the maximum depth d3 of the first shoulder sipe 21. The axial length L3 of the shallow bottom portion 23 is 10% to 30% of the axial width W3 (shown in FIG. 3) of the first shoulder land portion 11. The length L3 of the shallow bottom portion 23 is measured, for example, at the center position in the height direction of the shallow bottom portion 23. The first shoulder sipe 21 having such a shallow bottom portion 23 maintains the rigidity of the first shoulder land portion 11 and improves steering stability.

[0045] As shown in Fig. 3, the first middle land portion 12 includes a first longitudinal edge 12a on the first tread edge T1 side, a second longitudinal edge 12b on the second tread edge T2 side, and a tread surface between the first longitudinal edge 12a and the second longitudinal edge 12b. The first middle land portion 12 is provided with only sipes, thereby increasing the rigidity of the first middle land portion 12. In this embodiment, the first middle land portion 12 is provided with a plurality of first middle sipes 30 extending in the tire axial direction.

[0046] Fig. 6 shows a cross section of the first middle sipe 30 taken along line BB in Fig. 3. As shown in Fig. 6, the first middle sipe 30 includes a main body portion 30a extending in the tire radial direction and a widened portion 30b that opens at the tread surface of the land portion and has a width greater than that of the main body portion 30a. In this embodiment, the width of the main body portion is, for example, 0.5 to 1.5 mm.

[0047] The widened portion 30b of the first middle sipe 30 includes an inclined surface 25 extending from the main body portion 30a to the tread surface. The inclined surface 25 in this embodiment is flat and inclined at an angle θ2 of 30 to 60° with respect to the tire radial direction.

[0048] The depth d2 of the widened portion 30b of the first middle sipe 30 is 15% to 30% of the maximum depth d5 ​​of the first middle sipe 30. The depth d2 of the widened portion 30b of the first middle sipe 30 is, for example, 1.0 to 3.0 mm. In a more desirable embodiment, the depth d1 of the widened portion 21b of the first shoulder sipe 21 is smaller than the depth d2 of the widened portion 30b of the first middle sipe 30. The depth d1 of the widened portion 21b of the first shoulder sipe 21 is 50% to 90% of the depth d2 of the widened portion 30b of the first middle sipe 30, and preferably 60% to 80%.

[0049] The width W8 of the widened portion 30b of the first middle sipe 30 (the width along the tread surface in the cross section of the sipe) is, for example, 1.0 to 3.0 mm.

[0050] The first middle sipes 30 include an outer first middle sipe 31 extending from the first longitudinal edge 12a and having an interrupted end 31a within the first middle land portion 12, and an inner first middle sipe 32 extending from the second longitudinal edge 12b and having an interrupted end 32a within the first middle land portion 12.

[0051] The first middle sipes 30 extend linearly in a tread plan view. The first middle sipes 30 are inclined in a first direction relative to the tire axial direction. More specifically, the outer first middle sipes 31 and the inner first middle sipes 32 each extend linearly in a tread plan view and are inclined in a first direction relative to the tire axial direction.

[0052] The angle of the outer first middle sipes 31 relative to the tire axial direction and the angle of the inner first middle sipes 32 relative to the tire axial direction are each preferably 20° or more, more preferably 25° or more, and preferably 45° or less, more preferably 40° or less. Such outer first middle sipes 31 and inner first middle sipes 32 provide balanced frictional forces in the tire axial and circumferential directions.

[0053] The angle difference between the outer first middle sipes 31 and the inner first middle sipes 32 is preferably 10° or less, more preferably 5° or less, and in this embodiment, they are arranged parallel to each other. Such outer first middle sipes 31 and inner first middle sipes 32 can suppress uneven wear of the first middle land portion 12.

[0054] The outer first middle sipes 31 and the inner first middle sipes 32 are each discontinued without crossing the axial center of the first middle land portion 12. The axial length La of the outer first middle sipes 31 is 20% or more, more preferably 25% or more, and preferably 45% or less, and more preferably 40% or less, of the axial width W7 of the first middle land portion 12. Similarly, the axial length Lc of the inner first middle sipes 32 is 20% or more, more preferably 25% or more, and preferably 45% or less, and more preferably 40% or less, of the axial width W7 of the first middle land portion 12. Such outer first middle sipes 31 and inner first middle sipes 32 can improve ride comfort and noise performance while maintaining steering stability.

[0055] The discontinuous end 31a of the outer first middle sipe 31 and the discontinuous end 32a of the inner first middle sipe 32 are misaligned in the tire circumferential direction. The distance Lb in the tire circumferential direction between the discontinuous end 31a of the outer first middle sipe 31 and the discontinuous end 32a of the inner first middle sipe 32 is, for example, 50% or less of the tire circumferential pitch length P2 of the first middle sipe 30, and preferably 25% to 40%. In a more desirable embodiment, the distance Lb is in the range of the following equation (4). This makes it easier for the pitch sound of each sipe to become white noise, improving noise performance. Lb=2La±1(mm)…(4)

[0056] The pitch length P2 of the first middle sipes 30 is set to, for example, 80% to 120% of the pitch length P1 of the first shoulder sipes 21, and in a more desirable embodiment, these are set to be the same.

[0057] In this embodiment, the outer first middle sipes 31 communicate with the first shoulder circumferential grooves 5. In addition, in a plan view of the tread, the widened portions of the outer first middle sipes 31 overlap with regions obtained by extending the widened portions 21b of the first shoulder sipes 21 along their length. This allows the outer first middle sipes 31 and the first shoulder sipes 21 to cooperate to further improve wet performance.

[0058] The first middle sipes 30 have a constant depth in their length direction. More specifically, the outer first middle sipes 31 and the inner first middle sipes 32 each have a constant depth in their length direction. The depth of the inner first middle sipes 32 is, for example, 70% to 100% of the depth of the circumferential groove 3. The maximum depth of the outer first middle sipes 31 is smaller than the maximum depth of the inner first middle sipes 32. The maximum depth of the outer first middle sipes 31 is 30% to 70% of the maximum depth of the inner first middle sipes 32, and in a desirable embodiment, is 1.0 to 2.5 mm.

[0059] 6 can be applied to the outer first middle sipes 31 and the inner first middle sipes 32. Such outer first middle sipes 31 and inner first middle sipes 32 improve noise performance by converting the pitch noise of each sipe into white noise, and also improve ride comfort and handling stability in a balanced manner.

[0060] As shown in FIG. 3, the first middle land portion 12 is provided with, for example, first longitudinal sipes 33 extending in the tire circumferential direction. In this embodiment, the first longitudinal sipes 33 extend continuously in the tire circumferential direction. Such first longitudinal sipes 33 provide axial friction force during wet driving. Further embodiments of the first longitudinal sipes 33 will be described later.

[0061] The first longitudinal sipes 33 are provided, for example, in the central region when the first middle land portion 12 is divided into three equal parts in the axial direction. The axial distance from the first longitudinal sipes 33 to the axial center position of the first middle land portion 12 is preferably 10% or less of the axial width W7 of the first middle land portion 12, and more preferably 5% or less. Such an arrangement of the first longitudinal sipes 33 can suppress uneven wear of the first middle land portion 12.

[0062] Fig. 7 shows a cross-sectional view taken along line DD in Fig. 2. As shown in Fig. 7, the first longitudinal sipe 33 is configured to have, for example, a constant width from the open end to the bottom.

[0063] Fig. 8 shows an enlarged view of the first middle land portion 12, the crown land portion 13, and the second middle land portion 14. As shown in Fig. 8, the crown land portion 13 includes a first longitudinal edge 13a on the first tread edge T1 side, a second longitudinal edge 13b on the second tread edge T2 side, and a tread surface between the first longitudinal edge 13a and the second longitudinal edge 13b. Similarly, the second middle land portion 14 includes a first longitudinal edge 14a on the first tread edge T1 side, a second longitudinal edge 14b on the second tread edge T2 side, and a tread surface between the first longitudinal edge 14a and the second longitudinal edge 14b.

[0064] The axial width Wco of the outer ground contact surface 36 is, for example, 51% to 60%, and preferably 51% to 55%, of the axial width W9 of the ground contact surface of the crown land portion 13. This suppresses uneven wear of the crown land portion 13 and improves steering stability.

[0065] Only sipes are provided in the crown land portion 13. This increases the rigidity of the crown land portion 13.

[0066] The crown land portion 13 is provided with a plurality of crown sipes 40 inclined in a second direction (downward to the right in each drawing of this specification) that is opposite to the first direction with respect to the tire axial direction. The crown sipes 40 of this embodiment extend linearly and inclined in the second direction. These crown sipes 40 cooperate with the first middle sipes 30 to provide frictional forces in multiple directions, improving wet performance.

[0067] The circumferential pitch length P3 of the crown sipes 40 is, for example, 80% to 120% of the circumferential pitch length P2 (shown in FIG. 3) of the first middle sipes 30, and in this embodiment, these lengths are set to be the same. Such a sipe arrangement improves uneven wear resistance.

[0068] The angle of the crown sipes 40 with respect to the tire axial direction is preferably 20° or more, more preferably 25° or more, and is preferably 45° or less, more preferably 40° or less. The crown sipes 40 provide a well-balanced friction force in the tire circumferential direction and the tire axial direction.

[0069] The crown sipes 40 include outer crown sipes 41 extending from the first longitudinal edge 40a and having an interrupted end 41a within the crown land portion 13, and inner crown sipes 42 extending from the second longitudinal edge 40b and having an interrupted end 42a within the crown land portion 13.

[0070] The angle difference between the outer crown sipes 41 and the inner crown sipes 42 is preferably 10° or less, more preferably 5° or less, and in this embodiment, they are arranged parallel to each other. Such outer crown sipes 41 and inner crown sipes 42 suppress uneven wear of the crown land portion 13.

[0071] The outer crown sipes 41 and the inner crown sipes 42 are each discontinued without crossing the axial center position of the crown land portion 13. The axial length L4 of the outer crown sipes 41 and the axial length L5 of the inner crown sipes 42 are, for example, 20% to 35% of the axial width W9 of the crown land portion 13. Such outer crown sipes 41 and inner crown sipes 42 improve steering stability and ride comfort in a well-balanced manner.

[0072] The end 41a of the outer crown sipe 41 and the end 42a of the inner crown sipe 42 are misaligned in the tire circumferential direction. The distance L6 between the end 41a of the outer crown sipe 41 and the end 42a of the inner crown sipe 42 in the tire circumferential direction is preferably smaller than the distance Lb between the end 31a of the outer first middle sipe 31 and the end 32a of the inner first middle sipe 32 in the tire circumferential direction. Specifically, the distance L6 is preferably 70% or less, more preferably 60% or less, and preferably 30% or more, more preferably 40% or more of the distance Lb. This sipe arrangement converts the pitch noise of each sipe into white noise, improving noise performance.

[0073] The outer crown sipes 41 and the inner crown sipes 42 each have a constant depth in the length direction. The depth of the inner crown sipes 42 is, for example, 70% to 100% of the depth of the circumferential grooves 3. The maximum depth of the outer crown sipes 41 is smaller than the maximum depth of the inner crown sipes 42. The maximum depth of the outer crown sipes 41 is 30% to 70% of the maximum depth of the inner crown sipes 42, and in a desirable embodiment, is 1.0 to 2.5 mm.

[0074] The cross-sectional shape configuration of the first middle sipe 30 described in Fig. 6 can be applied to each of the outer crown sipe 41 and the inner crown sipe 42. Therefore, a description thereof will be omitted here.

[0075] Only sipes are provided in the second middle land portion 14. This increases the rigidity of the second middle land portion 14.

[0076] A plurality of second middle sipes 45 inclined in the second direction with respect to the tire axial direction are provided in the second middle land portion 14. The second middle sipes 45 of the present embodiment extend linearly and inclined in the second direction.

[0077] The circumferential pitch length P4 of the second middle sipes 45 is, for example, 80% to 120% of the circumferential pitch length P3 of the crown sipes 40, and in this embodiment, these lengths are set to be the same. Such a sipe arrangement improves uneven wear resistance.

[0078] The angle of the second middle sipes 45 with respect to the tire axial direction is preferably 20° or more, more preferably 25° or more, and is preferably 45° or less, more preferably 40° or less. The crown sipes 40 provide balanced frictional forces in the tire circumferential and axial directions.

[0079] The second middle sipes 45 include an outer second middle sipe 46 extending from the first longitudinal edge 14a and having an interrupted end 46a within the crown land portion 13, and an inner second middle sipe 47 extending from the second longitudinal edge 14b and having an interrupted end 47a within the crown land portion 13.

[0080] The angle difference between the outer second middle sipes 46 and the inner second middle sipes 47 is preferably 10° or less, more preferably 5° or less, and in this embodiment, they are arranged parallel to each other. Such outer second middle sipes 46 and inner second middle sipes 47 suppress uneven wear of the second middle land portion 14.

[0081] The outer second middle sipes 46 and the inner second middle sipes 47 are each discontinued without crossing the axial center position of the second middle land portion 14. The axial length L7 of the outer second middle sipes 46 and the axial length L8 of the inner second middle sipes 47 are, for example, greater than the length L4 of the outer crown sipes 41 and the length L5 of the inner crown sipes 42. The axial length L7 of the outer second middle sipes 46 and the axial length L8 of the inner second middle sipes 47 are preferably greater than the axial length of the first middle sipes 30. Specifically, the length L7 of the outer second middle sipes 46 and the length L8 of the inner second middle sipes 47 are 25% to 35% of the axial width W10 of the second middle land portion 14. Such outer second middle sipes 46 and inner second middle sipes 47 are useful for improving wet performance and ride comfort.

[0082] The end 46a of the outer second middle sipe 46 and the end 47a of the inner second middle sipe 47 are offset in the tire circumferential direction. The tire circumferential distance L9 between the end 46a of the outer second middle sipe 46 and the end 47a of the inner second middle sipe 47 is, for example, smaller than the tire circumferential distance Lb between the end 31a of the outer first middle sipe 31 and the end 32a of the inner first middle sipe 32, and preferably smaller than the tire circumferential distance L6 between the end 41a of the outer crown sipe 41 and the end 42a of the inner crown sipe 42. Specifically, the distance L9 is preferably 80% or less, more preferably 70% or less, and preferably 40% or more, more preferably 50% or more of the distance L6. Such a sipe arrangement optimizes the rigidity balance of each land portion, improving steering stability and ride comfort in a balanced manner.

[0083] The outer second middle sipes 46 and the inner second middle sipes 47 each have a constant depth in the length direction. The depth of the inner second middle sipes 47 is, for example, 70% to 100% of the depth of the circumferential groove 3. The maximum depth of the outer second middle sipes 46 is smaller than the maximum depth of the inner second middle sipes 47. The maximum depth of the outer second middle sipes 46 is 30% to 70% of the maximum depth of the inner second middle sipes 47, and in a desirable embodiment, is 1.0 to 2.5 mm. Such outer crown sipes 41 and inner crown sipes 42 convert the pitch noise of each sipe into white noise, improving noise performance and improving ride comfort and handling stability in a balanced manner.

[0084] 6 can be applied to the outer second middle sipes 46 and the inner second middle sipes 47. Therefore, the description here will be omitted.

[0085] The second middle land portion 14 is provided with, for example, second longitudinal sipes 48 extending in the tire circumferential direction. In this embodiment, the second longitudinal sipes 48 extend continuously in the tire circumferential direction. The second longitudinal sipes 48 have a cross-sectional shape similar to that of the above-described first longitudinal sipes 33. Such second longitudinal sipes 48 provide frictional force in the tire axial direction.

[0086] The second longitudinal sipes 48 are provided, for example, in the central region when the second middle land portion 14 is divided into three equal parts in the axial direction. The axial distance from the second longitudinal sipes 48 to the axial center position of the second middle land portion 14 is preferably 10% or less of the axial width W10 of the second middle land portion 14, and more preferably 5% or less.

[0087] Fig. 9 shows an enlarged view of the second shoulder land portion 15 of Fig. 1. As shown in Fig. 9, only sipes are provided in the second shoulder land portion 15. This increases the rigidity of the second middle land portion 14.

[0088] The second shoulder land portion 15 is provided with, for example, a plurality of second shoulder sipes 50 extending in the tire axial direction. In this embodiment, the total number of second shoulder sipes 50 is greater than the total number of first shoulder sipes 21 (shown in FIG. 3 , and the same applies hereinafter). Such a sipe arrangement improves noise performance and wet performance.

[0089] In order to improve noise performance and wet performance while maintaining steering stability, the total number of second shoulder sipes 50 is preferably 1.3 times or more, more preferably 1.5 times or more, and even more preferably 1.8 times or more, the total number of first shoulder sipes 21 (shown in FIG. 3), and is preferably 2.8 times or less, more preferably 2.5 times or less, and even more preferably 2.2 times or less.

[0090] The one-pitch length P5 of the second shoulder sipes 50 in the tire circumferential direction is, for example, 30% to 70% of the one-pitch length P4 (shown in FIG. 8) of the second middle sipes 45 in the tire circumferential direction.

[0091] The second shoulder sipes 50 are inclined, for example, in a first direction. That is, the first shoulder sipes 21 and the second shoulder sipes 50 are inclined in the same direction relative to the tire axial direction. The second shoulder sipes 50 of this embodiment extend linearly and inclined in the first direction.

[0092] The angle of the second shoulder sipes 50 relative to the tire axial direction is, for example, 20° or less, preferably 15° or less, and more preferably 10° or less. As a result, in this embodiment, the maximum angle of the first shoulder sipes 21 relative to the tire axial direction is greater than the maximum angle of the second shoulder sipes 50 relative to the tire axial direction. This sipe arrangement further improves noise performance.

[0093] The cross-sectional shape configuration of the first shoulder sipes 21 described in Fig. 4 can be applied to the second shoulder sipes 50. Therefore, the description here will be omitted.

[0094] The second shoulder sipes 50 include, for example, transverse second shoulder sipes 51 that completely cross the second shoulder land portion 15 in the tire axial direction, and interrupted second shoulder sipes 52 that extend in the tire axial direction from at least the second tread edge T2 and have interrupted ends within the second shoulder land portion 15.

[0095] The interrupted second shoulder sipes 52 have a longer axial length than any of the first middle sipes 30, crown sipes 40, and second middle sipes 45. The axial length L10 of the second shoulder sipes 50 is preferably 50% or more, more preferably 60% or more, and preferably 90% or less, more preferably 80% or less of the axial width W11 of the second shoulder land portion 15. Such interrupted second shoulder sipes 52 improve ride comfort and handling stability in a well-balanced manner.

[0096] FIG. 10 shows a cross-sectional view taken along line EE in FIG. 9. As shown in FIG. 10, the transverse second shoulder sipe 51 includes a shallow bottom portion 53 whose bottom portion is locally raised. The shallow bottom portion 53 in this embodiment is provided, for example, at a communicating portion with the second shoulder circumferential groove 8. The shallow bottom portion 53 of the second shoulder sipe 50 can have the same configuration as the shallow bottom portion 23 of the first shoulder sipe 21 (shown in FIG. 6), and a description thereof will be omitted here. The transverse second shoulder sipe 51 including such a shallow bottom portion 53 maintains the rigidity of the second shoulder land portion 15 and improves driving stability.

[0097] 1, in this embodiment, only sipes 16 are provided in each of the five land portions 4, and no lateral drainage grooves are provided. This maintains the rigidity of each land portion, and is expected to improve noise performance because pumping noise from the lateral grooves is not generated.

[0098] As a further desirable aspect, in this embodiment, the circumferential groove 3 includes a first groove wall 3a and a second groove wall 3b facing each other, and the first groove wall 3a is provided with a plurality of first recesses 56 recessed outward in the groove width direction from the groove edge of the circumferential groove 3 where the tread surface of the tread portion 2 appears. Also, the second groove wall 3b is provided with a plurality of second recesses 57 recessed outward in the groove width direction from the groove edge of the circumferential groove 3 where the tread surface of the tread portion 2 appears. Such first recesses 56 and second recesses 57 improve the drainage performance of the circumferential groove 3 and can effectively suppress hydroplaning. Furthermore, the first recesses 56 and second recesses 57 are expected to have the effect of attenuating the sound pressure of noise generated by the circumferential groove 3, and are also useful for improving noise performance.

[0099] It is desirable that the first recessed portion 56 gradually decreases in depth from the groove edge toward both sides in the tire circumferential direction from the deepest portion recessed furthest outward in the groove width direction. Similarly, it is desirable that the second recessed portion 57 gradually decreases in depth from the groove edge toward both sides in the tire circumferential direction from the deepest portion recessed furthest outward in the groove width direction. Such first recessed portion 56 and second recessed portion 57 can prevent the formation of portions in the land portion where rigidity is locally reduced, and suppress uneven wear of the land portion.

[0100] In order to further enhance the above-mentioned effect, it is desirable that the first recessed portions 56 and the second recessed portions 57 be provided alternately in the tire circumferential direction.

[0101] In this embodiment, the land portion is provided with a plurality of sipes that communicate with the circumferential grooves 3, and one first recessed portion 56 and one second recessed portion 57 are provided within a length that is 1.0 to 3.0 times the length of one sipe pitch. In other words, the tire circumferential length of each pair of first recessed portion 56 and second recessed portion 57 is 1.0 to 3.0 times the length of one sipe pitch. This improves noise performance while maintaining the rigidity of the land portion.

[0102] FIG. 11 shows a cross-sectional view taken along line FF in FIG. 1. FIG. 12 shows a cross-sectional view taken along line GG in FIG. 1. As shown in FIGS. 11 and 12, the first groove wall 3a and the second groove wall 3b have substantially the same shape. Furthermore, the first recess 56 and the second recess 57 have substantially the same shape. Therefore, the configuration of the first groove wall 3a described below can be applied to the second groove wall 3b. Furthermore, the configuration of the first recess 56 can be applied to the second recess 57.

[0103] The first groove wall 3a includes an outer portion 18 that extends from the groove edge of the circumferential groove 3 toward the radially inner side of the tire at an inclination such that the groove width decreases. The first groove wall 3a also includes an inner portion 19 that extends from the outer portion 18 toward the radially inner side of the tire at an inclination such that the groove width increases and is continuous with the groove bottom. This inner portion 19 forms the bottom surface of the first recess 56.

[0104] The height h1 of the first recessed portion 56 in the tire radial direction is, for example, 30% to 70%, and preferably 40% to 60%, of the total depth d6 of the circumferential groove 3. Such a first recessed portion 56 can improve wet performance and noise performance while suppressing uneven wear of the land portion.

[0105] From the same viewpoint, the depth d7 of the first recess 56 is, for example, 1.0 to 3.0 mm, and preferably 1.5 to 2.5 mm. Note that the depth d7 corresponds to the distance in the groove width direction (the direction parallel to the tread surface) from the first groove wall 3a where the first recess 56 is not provided to the deepest part of the first recess 56. Note that, needless to say, the height h1 and depth d7 of the first recess 56 described above can also be applied to the second recess 57.

[0106] Other embodiments of the present disclosure will be described below. In the drawings showing the other embodiments, the elements already described are assigned the same reference numerals as those described above, and the above-described configurations can be applied.

[0107] FIG. 13 shows an enlarged view of a first middle land portion 12 according to another embodiment. As shown in FIG. 13, the first longitudinal sipes 33 provided in the first middle land portion 12 extend in a zigzag pattern in the tire circumferential direction. The first longitudinal sipes 33 may extend in a wavy pattern with a smooth curve, for example. The axial amplitude A1 (peak-to-peak value) of the first longitudinal sipes 33 is, for example, 1.0% to 8.0% of the axial width W7 of the first middle land portion 12. The first longitudinal sipes 33 extend in a zigzag pattern so that one cycle corresponds to two pitches of the first middle sipes 30. Such first longitudinal sipes 33 can also provide friction in the tire circumferential direction.

[0108] Fig. 14 shows an enlarged view of a first middle land portion 12 according to yet another embodiment. As shown in Fig. 14, the first longitudinal sipes 33 provided in this first middle land portion 12 extend intermittently in the tire circumferential direction. That is, the first longitudinal sipes 33 are composed of a plurality of longitudinal sipe pieces 54 arranged in the tire circumferential direction. The tire circumferential length L11 of one longitudinal sipe piece 54 is, for example, 20% to 60% of the tire circumferential pitch length P2 of the first middle sipes 30. Such first longitudinal sipes 33 can provide axial friction while maintaining the rigidity of the first middle land portion 12.

[0109] The configuration of the first longitudinal sipes 33 shown in FIGS. 13 and 14 can also be applied to the second longitudinal sipes 48 provided in the second middle land portion 14.

[0110] FIG. 15 shows a developed view of the tread portion 2 of yet another embodiment. This embodiment also has the above-described contact patch configuration, and therefore, a description thereof will be omitted here. FIG. 16 shows an enlarged view of the first middle land portion 12 of the embodiment shown in FIG. 15. As shown in FIG. 16, the first middle land portion 12 of this embodiment is provided with, in addition to the above-described first longitudinal sipes 33, a plurality of first middle sipes 30 that completely cross the first middle land portion 12 in the tire axial direction. Such first middle sipes 30 can provide high friction on wet roads while maintaining steering stability.

[0111] The circumferential pitch length P1 of the plurality of first middle sipes 30 is, for example, 100% to 150% of the width W7 of the contact patch of the first middle land portion 12. This can improve the steering stability and wet performance in a well-balanced manner.

[0112] The first middle sipes 30 of this embodiment extend linearly and inclined in the first direction (upward and to the right) relative to the tire axial direction. The angle of the first middle sipes 30 relative to the tire axial direction is, for example, 30 to 50 degrees. Such first middle sipes 30 can also provide frictional force in the tire axial direction when traveling on wet roads.

[0113] The first middle sipe 30 has a cross-sectional shape similar to that shown in Fig. 6, for example. That is, the first middle sipe 30 shown in Fig. 16 includes a main body portion 30a and an expanded portion 30b that opens at the tread surface of the land portion and has a width greater than that of the main body portion 30a. In a more preferred embodiment, the width of the expanded portion 30b of the first middle sipe 30 in this embodiment desirably increases continuously from the first shoulder circumferential groove 5 to the first crown circumferential groove 6. Such a first middle sipe 30 helps to uniform the ground pressure acting on the tread surface of the first middle land portion 12 and suppress uneven wear.

[0114] FIG. 17 shows a cross section taken along line HH in FIG. 16. As shown in FIG. 17, the first middle sipe 30 includes, for example, a first middle tie bar 34 whose bottom is locally raised. The first middle tie bar 34 is disposed, for example, in the central region when the first middle sipe 30 is divided into thirds in the axial direction. The axial length L12 of the first middle tie bar 34 is 30% to 50% of the axial width W7 (shown in FIG. 16) of the contact patch of the first middle land portion 12. Note that, if the axial length of the first middle tie bar 34 varies in the radial direction of the tire, the length is measured at the center position in the radial direction of the tire. The depth d9 from the contact patch of the first middle land portion 12 to the outer surface of the first middle tie bar 34 is 50% to 70% of the maximum depth d8 of the first middle sipe 30. Such a first middle tie bar 34 can maintain the rigidity of the first middle land portion 12, and can further improve the steering stability.

[0115] As shown in FIG. 16, the first middle land portion 12 of this embodiment is provided with first longitudinal sipes 33. The first longitudinal sipes 33 of this embodiment extend linearly, for example, parallel to the tire circumferential direction. The opening width of the first longitudinal sipes 33 is, for example, 0.5 to 2.0 mm, and the depth is 1.0 to 4.0 mm. The configuration of the first longitudinal sipes 33 already described can be applied to the first longitudinal sipes 33. Therefore, the configuration of the first longitudinal sipes 33 already described may be applied to the embodiment shown in FIGS. 15 and 16.

[0116] Therefore, the first middle land portion 12 of this embodiment may be provided with a plurality of first longitudinal sipes 33 extending intermittently in the tire circumferential direction (not shown). In this case, it is desirable that the plurality of first longitudinal sipes 33 are arranged without communicating with the first middle sipes 30. In other words, it is desirable that the first middle sipes 30 do not intersect with the first longitudinal sipes 33, and that both ends of the first middle sipes 30 in the tire circumferential direction are discontinued within the blocks between the two first middle sipes 30. Furthermore, in this case, it is desirable that the length of one first longitudinal sipe 33 in the tire circumferential direction is 70% or more of the one pitch length P1 of the first middle sipes 30. In this embodiment, since the first middle sipes 30 and the first longitudinal sipes 33 do not communicate with each other, uneven wear of the first middle land portion 12 can be suppressed.

[0117] FIG. 18 shows a modified example of the first longitudinal sipes 33 in the embodiment shown in FIG. 15. As shown in FIG. 18, the first longitudinal sipes 33 extend axially in a wave-like manner with amplitude. The first longitudinal sipes 33 preferably extend, for example, in a sinusoidal manner. The axial amplitude A2 (peak-to-peak value) of the first longitudinal sipes 33 is, for example, 1.0% to 8.0% of the axial width W7 of the tread surface of the first middle land portion 12. The wavelength L13 of the first longitudinal sipes 33 is 150% to 250%, and preferably 180% to 220%, of the one-pitch length P1 of the first middle sipes 30. Such first longitudinal sipes 33 can improve wet performance while maintaining the rigidity of the first middle land portion 12.

[0118] As shown in FIG. 15 , the second middle land portion 14 of this embodiment is provided with a plurality of second middle sipes 45 similar to the first middle sipes 30 described above. That is, the second middle sipes 45 are inclined in the same direction as the first middle sipes 30 relative to the tire axial direction. These second middle sipes 45 can cooperate with the first middle sipes 30 to improve steering stability and wet performance. The second middle land portion 14 is also provided with second longitudinal sipes 48 similar to the first longitudinal sipes 33 described above. The configuration of the first longitudinal sipes 33 can be applied to these second longitudinal sipes 48.

[0119] The crown land portion 13 of this embodiment is provided with a plurality of crown sipes 40 that are inclined in the same direction as the first middle sipes with respect to the tire axial direction. The width of the widened portions of these crown sipes 40 decreases toward the tire equator C. These crown sipes 40 ensure a large contact area of ​​the crown land portion 13 near the tire equator C, thereby enhancing excellent steering stability. The various configurations already described can be applied to the crown sipes 40 of the embodiment of FIG. 15 .

[0120] In this embodiment, the first shoulder sipe 21 provided in the first shoulder land portion 11 includes an inclined portion 26 extending from the first shoulder circumferential groove 5 at an angle with respect to the tire axial direction, and an axial portion 27 continuing from the inclined portion 26 and extending along the tire axial direction. A similar sipe is also provided in the second shoulder land portion 15. Such a sipe can also provide friction force in the tire axial direction on wet road surfaces.

[0121] The first shoulder land portion 11 is also provided with interrupted sipes 28 that extend from the first shoulder circumferential groove 5 and terminate without reaching the first tread edge T1. Such interrupted sipes 28 can improve wet performance while maintaining the rigidity of the first shoulder land portion 11.

[0122] Although a tire according to one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the above-described specific embodiment and can be modified and implemented in various aspects. [Example]

[0123] A tire of size 235 / 55R19 having the basic pattern of Fig. 1 was prototyped based on the specifications of Tables 1 to 3. In addition, a tire having the pattern shown in Fig. 19 was prototyped as a reference tire (reference tire) for comparing noise performance.

[0124] Each land portion of this reference tire is a sipe similar to that shown in FIG. 1, with the widened portion removed. The reference tire has the same width Wa of the first shoulder land portion a and the same width We of the second shoulder land portion e. The same width Wb of the first middle land portion b, the same width Wc of the crown land portion c, and the same width Wd of the second middle land portion d. The widths Wa and We are greater than the widths Wc, Wd, and We. As a result, the reference tire satisfies the following formula (5) under a 50% load condition, when the axial widths of the ground contact patches of the first shoulder land portion a, the first middle land portion b, the crown land portion c, the second middle land portion d, and the second shoulder land portion e are W1s, W1m, Wc, W2m, and W2s, respectively. The same width Wco of the outer ground contact patch and the same width Wci of the inner ground contact patch of the crown land portion c are also used. W1s=W2s>W1m=Wc=W2m…(5)

[0125] Additionally, a tire having the pattern shown in Figure 20 was produced as a comparative example. The comparative tire has the same land width distribution as the reference tire, and each sipe has a widened portion as in Figure 1. Except for the above-mentioned features, the comparative tire is substantially the same as the tire shown in Figure 1. Each test tire was tested for steering stability and noise performance on dry roads. The common specifications and test methods for each test tire are as follows: Rim: 19 x 7.0J Tire pressure: 230kPa Test vehicle: 2000cc, four-wheel drive Tire mounting position: All wheels

[0126] <Steering stability on dry roads> The test vehicle was driven on a public road and the handling stability on dry roads was evaluated by the driver. The results were evaluated as a score based on the handling stability of the comparative example being 100, with a higher score indicating better handling stability on dry roads.

[0127] <Noise performance> The test vehicle was driven on a dry road at a speed of 40 to 100 km / h, and the maximum sound pressure of noise inside the vehicle was measured. The results are expressed as an index where the reduction in sound pressure, which is the difference from the sound pressure of the reference tire, is set to the reduction in sound pressure of the comparative tire as 100. The larger this index, the smaller the maximum sound pressure of the noise, indicating excellent noise performance. The test results are shown in Tables 1-3.

[0128] [Table 1]

[0129] [Table 2]

[0130] [Table 3]

[0131] As a result of the test, it was confirmed that the tires of the examples had improved steering stability on dry roads. It was also confirmed that the tires of the examples had improved noise performance.

[0132] [Note] The present disclosure includes the following aspects.

[0133] [Disclosure 1] A tire having a tread portion whose mounting direction on a vehicle is specified, the tread portion includes a first tread edge that is on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is on the inner side 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 that are divided by the circumferential grooves, the plurality of land portions include a crown land portion disposed on the tire equator, a first middle land portion adjacent to the crown land portion on the first tread edge side, and a second middle land portion adjacent to the crown land portion on the second tread edge side, When the tire is mounted on a regular rim with a regular internal pressure, and is placed on a flat surface with a camber angle of 0° and a load of 50% of the regular load is applied, the widths of the contact patches in the tire axial direction of the first middle land portion, the crown land portion, and the second middle land portion are W1m, Wc, and W2m, respectively, and the following formula (1) is satisfied: the crown land portion includes an outer ground contact surface located closer to a first tread edge than the tire equator and an inner ground contact surface located closer to a second tread edge than the tire equator, When the widths of the outer contact surface and the inner contact surface in the tire axial direction are Wco and Wci, respectively, the following formula (2) is satisfied: tire. W1m>Wc>W2m…(1) Wco>Wci…(2) [Disclosure 2] The tire according to any one of the first disclosures, wherein the width of the outer ground contact surface in the tire axial direction is 51% to 55% of the width of the ground contact surface of the crown land portion in the tire axial direction. [Disclosure 3] The tire according to Disclosure 1 or 2, wherein the first middle land portion is provided with a first longitudinal sipe extending in the tire circumferential direction. [Disclosure 4] The tire according to Disclosure 3, wherein the first longitudinal sipe extends continuously in the tire circumferential direction. [Disclosure 5] The tire according to Disclosure 4, wherein the first longitudinal sipe extends in a zigzag pattern. [Disclosure 6] The tire according to Disclosure 3, wherein the first longitudinal sipes extend discontinuously in the tire circumferential direction. [Disclosure 7] the first middle land portion includes a first longitudinal edge on the first tread end side, a second longitudinal edge on the second tread end side, and a tread surface between the first longitudinal edge and the second longitudinal edge, A tire described in any one of Disclosures 1 to 6, wherein the first middle land portion is provided with an outer first middle sipe that is connected to the first longitudinal edge and has an interrupted end within the first middle land portion, and an inner first middle sipe that is connected to the second longitudinal edge and has an interrupted end within the first middle land portion. [Disclosure 8] The tire according to Disclosure 7, wherein the axial length of the outer first middle sipe is 20% to 45% of the axial width of the first middle land portion. [Disclosure 9] The tire according to Disclosure 7 or 8, wherein the axial length of the inner first middle sipe is 20% to 45% of the axial width of the first middle land portion. [Disclosure 10] The tire according to any one of Present Disclosures 1 to 6, wherein the first middle land portion is provided with a plurality of first middle sipes that completely cross the first middle land portion in the tire axial direction. [Disclosure 11] The first middle sipe is inclined with respect to the tire axial direction, The tire according to Disclosure 10, wherein the second middle land portion is provided with a plurality of second middle sipes inclined in the same direction as the first middle sipes with respect to the tire axial direction. [Disclosure 12] The first middle sipe is inclined with respect to the tire axial direction, The tire according to Disclosure 10 or 11, wherein the crown land portion is provided with a plurality of crown sipes inclined in the same direction as the first middle sipes with respect to the tire axial direction. [Disclosure 13] the circumferential groove includes a first groove wall and a second groove wall facing each other, The first groove wall is provided with a plurality of first recesses recessed outward in a groove width direction from a groove edge of the circumferential groove where a tread surface of the tread portion appears, The second groove wall is provided with a plurality of second recesses recessed outward in a groove width direction from a groove edge of the circumferential groove where a tread surface of the tread portion appears, The first recessed portion and the second recessed portion have a recession amount from the groove edge gradually decreasing from a deepest portion recessed furthest outward in the groove width direction to both sides in the tire circumferential direction, a plurality of sipes communicating with the circumferential grooves are provided in the tire circumferential direction in the land portion adjacent to the circumferential groove; The tire according to any one of Disclosures 1 to 12, wherein one of the first recessed portions and one of the second recessed portions are provided within a length that is 1.0 to 3.0 times the pitch length of the sipe. [Explanation of symbols]

[0134] 2 Tread section 3 Circumferential groove 4 Land 12 First Middle Track Division 13 Crown Land Division 14 Second Middle Track Division 36 Outer ground plane 37 Inner ground plane T1 First tread edge T2 Second tread edge

Claims

1. A tire having a tread portion whose mounting direction on a vehicle is specified, the tread portion includes a first tread edge that is on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is on the inner side 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 that are divided by the circumferential grooves, the plurality of land portions include a crown land portion disposed on the tire equator, a first middle land portion adjacent to the crown land portion on the first tread edge side, and a second middle land portion adjacent to the crown land portion on the second tread edge side, When the tire is mounted on a regular rim with a regular internal pressure, and is placed on a flat surface with a camber angle of 0° and a load of 50% of the regular load is applied, the tire axial widths of the contact patches of the first middle land portion, the crown land portion, and the second middle land portion are W1m, Wc, and W2m, respectively, and the following formula (1) is satisfied: the crown land portion includes an outer ground contact surface located closer to a first tread edge than the tire equator and an inner ground contact surface located closer to a second tread edge than the tire equator, When the widths of the outer and inner ground contact surfaces in the tire axial direction are Wco and Wci, respectively, the following formula (2) is satisfied: The width of the outer ground contact surface in the tire axial direction is 51% to 55% of the width of the ground contact surface of the crown land portion in the tire axial direction. tire. W1m>Wc>W2m...(1) Wco>Wci…(2)

2. A tire having a tread portion whose mounting direction on a vehicle is specified, the tread portion includes a first tread edge that is on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is on the inner side 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 that are divided by the circumferential grooves, the plurality of land portions include a crown land portion disposed on the tire equator, a first middle land portion adjacent to the crown land portion on the first tread edge side, and a second middle land portion adjacent to the crown land portion on the second tread edge side, When the tire is mounted on a regular rim with a regular internal pressure, and is placed on a flat surface with a camber angle of 0° and a load of 50% of the regular load is applied, the tire axial widths of the contact patches of the first middle land portion, the crown land portion, and the second middle land portion are W1m, Wc, and W2m, respectively, and the following formula (1) is satisfied: the crown land portion includes an outer ground contact surface located closer to a first tread edge than the tire equator and an inner ground contact surface located closer to a second tread edge than the tire equator, When the widths of the outer and inner ground contact surfaces in the tire axial direction are Wco and Wci, respectively, the following formula (2) is satisfied: The first middle land portion is provided with a first longitudinal sipe extending in the tire circumferential direction, The first longitudinal sipe extends continuously in the tire circumferential direction. tire. W1m>Wc>W2m...(1) Wco>Wci…(2)

3. A tire having a tread portion whose orientation when mounted on a vehicle is specified, the tread portion includes a first tread edge that is on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is on the inner side 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 that are divided by the circumferential grooves, the plurality of land portions include a crown land portion disposed on the tire equator, a first middle land portion adjacent to the crown land portion on the first tread edge side, and a second middle land portion adjacent to the crown land portion on the second tread edge side, When the tire is mounted on a regular rim with a regular internal pressure, and is placed on a flat surface with a camber angle of 0° and a load of 50% of the regular load is applied, the tire axial widths of the contact patches of the first middle land portion, the crown land portion, and the second middle land portion are W1m, Wc, and W2m, respectively, and the following formula (1) is satisfied: the crown land portion includes an outer ground contact surface located closer to a first tread edge than the tire equator and an inner ground contact surface located closer to a second tread edge than the tire equator, When the widths of the outer and inner ground contact surfaces in the tire axial direction are Wco and Wci, respectively, the following formula (2) is satisfied: the first middle land portion includes a first longitudinal edge on the first tread end side, a second longitudinal edge on the second tread end side, and a tread surface between the first longitudinal edge and the second longitudinal edge, The first middle land portion is provided with an outer first middle sipe that is connected to the first longitudinal edge and has an end that is disconnected within the first middle land portion, and an inner first middle sipe that is connected to the second longitudinal edge and has an end that is disconnected within the first middle land portion, The length of the outer first middle sipe in the tire axial direction is 20% to 45% of the width of the first middle land portion in the tire axial direction. tire. W1m>Wc>W2m...(1) Wco>Wci…(2)

4. A tire having a tread portion whose mounting direction on a vehicle is specified, the tread portion includes a first tread edge that is on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is on the inner side 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 that are divided by the circumferential grooves, the plurality of land portions include a crown land portion disposed on the tire equator, a first middle land portion adjacent to the crown land portion on the first tread edge side, and a second middle land portion adjacent to the crown land portion on the second tread edge side, When the tire is mounted on a regular rim with a regular internal pressure, and is placed on a flat surface with a camber angle of 0° and a load of 50% of the regular load is applied, the tire axial widths of the contact patches of the first middle land portion, the crown land portion, and the second middle land portion are W1m, Wc, and W2m, respectively, and the following formula (1) is satisfied: the crown land portion includes an outer ground contact surface located closer to a first tread edge than the tire equator and an inner ground contact surface located closer to a second tread edge than the tire equator, When the widths of the outer and inner ground contact surfaces in the tire axial direction are Wco and Wci, respectively, the following formula (2) is satisfied: the first middle land portion includes a first longitudinal edge on the first tread end side, a second longitudinal edge on the second tread end side, and a tread surface between the first longitudinal edge and the second longitudinal edge, The first middle land portion is provided with an outer first middle sipe that is connected to the first longitudinal edge and has an end that is disconnected within the first middle land portion, and an inner first middle sipe that is connected to the second longitudinal edge and has an end that is disconnected within the first middle land portion, The length of the inner first middle sipe in the tire axial direction is 20% to 45% of the width of the first middle land portion in the tire axial direction. tire. W1m>Wc>W2m...(1) Wco>Wci…(2)

5. A tire having a tread portion whose orientation when mounted on a vehicle is specified, the tread portion includes a first tread edge that is on the outer side of the vehicle when mounted on the vehicle, a second tread edge that is on the inner side 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 that are divided by the circumferential grooves, the plurality of land portions include a crown land portion disposed on the tire equator, a first middle land portion adjacent to the crown land portion on the first tread edge side, and a second middle land portion adjacent to the crown land portion on the second tread edge side, When the tire is mounted on a regular rim with a regular internal pressure, and is placed on a flat surface with a camber angle of 0° and a load of 50% of the regular load is applied, the tire axial widths of the contact patches of the first middle land portion, the crown land portion, and the second middle land portion are W1m, Wc, and W2m, respectively, and the following formula (1) is satisfied: the crown land portion includes an outer ground contact surface located closer to a first tread edge than the tire equator and an inner ground contact surface located closer to a second tread edge than the tire equator, When the widths of the outer and inner ground contact surfaces in the tire axial direction are Wco and Wci, respectively, the following formula (2) is satisfied: The first middle land portion is provided with a plurality of first middle sipes that completely cross the first middle land portion in the tire axial direction. tire. W1m>Wc>W2m...(1) Wco>Wci…(2)

6. A tire described in any one of claims 2 to 5, wherein the axial width of the outer contact surface is 51% to 55% of the axial width of the contact surface of the crown land portion.

7. A tire as described in any one of claims 1, 3, 4, and 5, wherein the first middle land portion is provided with a first longitudinal sipe extending circumferentially around the tire.

8. A tire as described in claim 7, wherein the first longitudinal sipe extends continuously in the circumferential direction of the tire.

9. A tire as described in claim 8, wherein the first longitudinal sipe extends in a zigzag pattern.

10. A tire as described in claim 7, wherein the first longitudinal sipes extend intermittently in the circumferential direction of the tire.

11. The first middle land portion includes a first vertical edge on the first tread end side, a second vertical edge on the second tread end side, and a tread surface between the first vertical edge and the second vertical edge, 6. The tire according to claim 1, wherein the first middle land portion is provided with an outer first middle sipe that is connected to the first longitudinal edge and has an end that is disconnected within the first middle land portion, and an inner first middle sipe that is connected to the second longitudinal edge and has an end that is disconnected within the first middle land portion.

12. A tire as described in claim 11, wherein the axial length of the outer first middle sipe is 20% to 45% of the axial width of the first middle land portion.

13. A tire as described in claim 11 or 12, wherein the axial length of the inner first middle sipe is 20% to 45% of the axial width of the first middle land portion.

14. A tire as described in any one of claims 1 to 4, wherein the first middle land portion is provided with a plurality of first middle sipes that completely traverse the first middle land portion in the tire axial direction.

15. The first middle sipe is inclined with respect to the tire axial direction, The tire according to claim 14, wherein the second middle land portion is provided with a plurality of second middle sipes inclined in the same direction as the first middle sipes with respect to the tire axial direction.

16. The first middle sipe is inclined with respect to the tire axial direction, The tire according to claim 14 or 15, wherein the crown land portion is provided with a plurality of crown sipes inclined in the same direction as the first middle sipes with respect to the tire axial direction.

17. The circumferential groove includes a first groove wall and a second groove wall facing each other, the first groove wall is provided with a plurality of first recesses recessed outward in a groove width direction from a groove edge of the circumferential groove where a tread surface of the tread portion appears, the second groove wall is provided with a plurality of second recesses recessed outward in a groove width direction from a groove edge of the circumferential groove where a tread surface of the tread portion appears, The first recess and the second recess have a recess amount from the groove edge gradually decreasing from a deepest portion recessed furthest outward in the groove width direction to both sides in the tire circumferential direction, a plurality of sipes communicating with the circumferential grooves are provided in the tire circumferential direction in the land portion adjacent to the circumferential groove; The tire according to any one of claims 1 to 16, wherein one each of the first recessed portion and the second recessed portion is provided within a length that is 1.0 to 3.0 times a pitch length of the sipe.

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