tire

Abstract

To provide a tire that can improve handling stability and drainage performance. [Solution] The tire 1 comprises a circumferential groove and a plurality of ribs, the plurality of circumferential grooves including a plurality of main grooves with a groove width of 3 mm or more, and having a first rib 210 which is located inward in the vehicle width direction from the outer main groove 130 which is located out main grooves, and which is offset outward in the vehicle width direction from the tire equator S2, and the groove width of the outer main groove 130 adjacent to the outer side of the first rib 210 in the vehicle width direction is greater than the groove width of the inner circumferential groove 140 adjacent to the inner side of the first rib 210 in the vehicle width direction from the circumferential groove.

Description

Technical Field

[0001] The present disclosure relates to a tire.

Background Art

[0002] In recent years, asymmetric pattern tires with different tread patterns on the outer side and the inner side in the vehicle width direction have been used (see, for example, Patent Document 1). Patent Document 1 discloses an asymmetric pattern tire having a plurality of ribs divided by a plurality of main grooves. Further, Patent Document 1 discloses a sipe with one side blocked.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, main grooves are arranged on both sides of the rib portion provided inside the outermost main groove in the vehicle width direction, and the width of the main groove on the outer side in the vehicle width direction is narrower than the width of the main groove on the inner side in the vehicle width direction. Therefore, there is a concern about a decrease in drainage performance on the outside of the vehicle.

[0005] An object of the present disclosure is to provide a tire capable of improving handling stability and drainage performance.

Means for Solving the Problems

[0006] The tire of this disclosure is a tire for which a mounting direction is specified, and comprises a plurality of circumferential grooves having a groove width of more than 2 mm and extending in the circumferential direction of the tire, and a plurality of ribs that are separated by the circumferential grooves and extend continuously in a rib shape over the entire circumference in the circumferential direction of the tire, wherein the plurality of circumferential grooves include a plurality of main grooves having a groove width of 3 mm or more, and has a first rib that is located inward in the vehicle width direction from the outer main groove which is located outward in the vehicle width direction of the main grooves, and is offset outward in the vehicle width direction from the tire equator, and the groove width of the outer main groove which is adjacent to the outer side of the first rib in the vehicle width direction is greater than the groove width of the inner circumferential groove which is adjacent to the inner side of the first rib in the vehicle width direction. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a tire that can improve handling stability and drainage performance. [Brief explanation of the drawing]

[0008] [Figure 1] This is a partial perspective view of tire 1 as shown in this disclosure, viewed from the outside in the vehicle width direction. [Figure 2] This is a partial perspective view of tire 1 as shown in this disclosure, viewed from the inside in the vehicle width direction. [Figure 3] This is a partial unfolded view showing the tread surface of tire 1 according to the present disclosure in a planar manner. [Figure 4] This is a partially enlarged unfolded view of Figure 3, which is a further partial enlargement. [Figure 5] This is a cross-sectional view of the tire axial direction, obtained by cutting tire 1 at the position indicated by arrow AA in Figure 3. [Figure 6] This figure shows the contact pattern when the tire 1 of this embodiment is placed on the ground under a normal load. [Figure 7] This is a cross-sectional view of the second rib closure slit 520, taken at the position of arrow EE in Figure 4, in a direction perpendicular to the extension direction of the second rib closure slit 520. [Figure 8]This is a cross-sectional view of the third rib closure slit 530, taken at the position indicated by arrow DD in Figure 4, in a direction perpendicular to the extension direction of the third rib closure slit 530. [Modes for carrying out the invention]

[0009] The following describes one embodiment for implementing this disclosure with reference to drawings and other documents.

[0010] (Embodiment) Figure 1 is a partial perspective view of the tire 1 according to this disclosure, viewed from the outside in the vehicle width direction. Figure 2 is a partial perspective view of the tire 1 according to this disclosure, viewed from the inside in the vehicle width direction. Figure 3 is a partial unfolded view showing the tread surface of the tire 1 according to this disclosure unfolded in a planar manner. Figure 4 is a partially enlarged unfolded view of Figure 3. Figure 5 is a cross-sectional view in the tire axis direction, obtained by cutting the tire 1 at the position of arrow AA in Figure 3. The tire 1 according to this embodiment is, for example, a tire for a passenger car. The configuration of the tire 1 according to this embodiment can be used for various vehicles other than passenger cars, such as light trucks, trucks, and buses. Furthermore, although the following description uses a pneumatic tire as an example, a non-pneumatic tire may also be used.

[0011] The cross-sectional shapes shown in Figures 1, 2, and 5 are axial cross-sectional views (tire meridian cross-sections) of the tire in an unloaded state, mounted on a standard rim (not shown) and filled with the standard internal pressure. The standard rim is the rim specified for each tire in the standard system, including the standard on which the tire is based. For example, it is the standard rim for JATMA, and the "Measuring Rim" for TRA and ETRTO. The standard internal pressure is the air pressure specified for each tire in the standard system, including the standard on which the tire is based. For truck and bus tires and light truck tires, it is the maximum air pressure for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and the "INFLATION PRESSURE" for ETRTO. For passenger car tires, it is usually 180 kPa, but for tires marked "Extra Load" or "Reinforced," it is 220 kPa.

[0012] In Figure 5, the symbol S1 represents the tire equatorial plane. The tire equatorial plane S1 is a plane perpendicular to the tire rotation axis and located at the center of the tire axial direction. The basic internal structure of tire 1 is symmetrical in the tire axial cross-section with respect to the tire equatorial plane S1. As will be described later, the tread pattern of tire 1 in this embodiment is asymmetrical in the tire axial direction, so the internal structure of tire 1 may also be asymmetrical.

[0013] Here, the tire axis direction is the direction parallel to the tire rotation axis, and in the cross-sectional view of Figure 5, it is the left-right direction on the paper. In Figures 1, 2, and 5, it is shown as the tire axis direction X. The inner direction in the tire axis direction is the direction approaching the tire equatorial plane S1, and in Figure 5, it is the center side of the paper. The outer direction in the tire axis direction is the direction away from the tire equatorial plane S1, and in Figure 5, it is the left and right sides of the paper. The tire radial direction is the direction perpendicular to the tire rotation axis, and in Figure 1, it is the up-down direction on the paper. In Figures 1, 2, and 5, it is shown as the tire radial direction Y. The outer direction in the tire radial direction is the direction away from the tire rotation axis, and in Figure 5, it is the top side of the paper. The inner direction in the tire radial direction is the direction approaching the tire rotation axis, and in Figure 5, it is the bottom side of the paper.

[0014] The tread pattern 38 provided on the tread surface 37 of the tire 1 in the embodiments shown in Figures 1 to 5 is asymmetrical in the tire axial direction, and the tire 1 has a designated mounting direction relative to the vehicle. That is, of the two sides in the tire axial direction when the tire 1 is mounted on the vehicle, the side that is positioned on the outside of the vehicle and the side that is positioned on the inside of the vehicle are designated. The mounting direction is based on the tread pattern 38. In Figures 1 to 5, the side of the tire 1 that is positioned on the outside of the vehicle is shown as the outside in the vehicle width direction, and the side that is positioned on the inside of the vehicle is shown as the inside in the vehicle width direction.

[0015] The tire 1 of the embodiment includes a pair of beads (not shown) provided on both sides in the tire axial direction, a pair of sidewalls (not shown) extending radially outward in the tire diameter direction from each of the pair of beads, a tread 30 disposed between the pair of sidewalls, a pair of shoulders 40 which are portions transitioning from each of the pair of sidewalls to the tread 30, a carcass ply (not shown) bridged and disposed between the pair of beads, and an inner liner (not shown) disposed on the tire inner cavity side of the carcass ply. Note that specific forms inside the tire such as beads, sidewalls, carcass plies, inner liners, etc. can use conventionally known configurations as appropriate, so detailed descriptions are omitted. Also, in addition to beads, sidewalls, carcass plies, inner liners, etc., additional configurations may be provided, or some of these may be omitted.

[0016] The tread 30 has a tread rubber 36. The tread rubber 36 is disposed radially outside the tire diameter of the cap ply (not shown). The tread rubber 36 constitutes the tread surface 37 which is the outer surface of the tread 30.

[0017] The shoulder 40 includes an inner shoulder 40A disposed on the inner side in the vehicle width direction and an outer shoulder 40B disposed on the outer side in the vehicle width direction when the tire 1 is mounted on a vehicle.

[0018] Next, the tread pattern 38 will be described. FIGS. 3 and 4 show the tire axial direction X, the outer side in the vehicle width direction, the inner side in the vehicle width direction, as well as the tire circumferential direction C and the tire equator S2. The tire equator S2 is a virtual line extending along the tire circumferential direction at the center in the tire axial direction.

[0019] As shown in FIGS. 1 to 5, the tread surface 37 of the tire 1 of the present embodiment is provided with grooves extending in the tire circumferential direction and grooves having a component extending in the tire axial direction. On the tread surface 37 of the tire 1 of the present embodiment, as grooves extending in the tire circumferential direction, circumferential grooves (main grooves 100 (110, 120, 130) and inner circumferential grooves 140) and circumferential sipes 150 are provided. Further, the tread pattern 38 includes a plurality of ribs 200 (210, 220, 230, 240, 250) divided by a plurality of circumferential grooves (main grooves 100 (110, 120, 130) and inner circumferential grooves 140).

[0020] The plurality of circumferential grooves (main grooves 100 (110, 120, 130) and inner circumferential grooves 140) are grooves having a groove width opening to the tread surface 37 exceeding 2 mm and extending in the tire circumferential direction. In the tire 1 of the present embodiment, as circumferential grooves, it has main grooves 100 (110, 120, 130) and inner circumferential grooves 140 which are narrow grooves, but it may further include other circumferential grooves or the number of main grooves may be reduced.

[0021] The main groove refers to a groove having a groove width of 3 mm or more and extending in the tire circumferential direction. On the tread surface 37 of the present embodiment, main grooves 100 (110, 120, 130) are provided as main grooves.

[0022] In the present specification, when an inclined surface provided in a chamfered shape at the edge of the groove extends along the extending direction of the groove, the width including the end portion of this inclined surface is regarded as the groove width. Further, in the case of a groove whose groove width changes depending on the position in the extending direction of the groove, the groove width (maximum groove width) of the portion where the width is maximum is regarded as the groove width of the groove.

[0023] A narrow groove is a groove that extends in the circumferential direction and includes a portion with a groove width exceeding 2 mm but less than 3 mm. In this embodiment, the tread surface 37 is provided with an inner circumferential groove 140 as a narrow groove. In this embodiment, the inner circumferential groove 140 has a groove width of 1.00 mm at its narrowest point (minimum groove width) and a maximum groove width of 3.58 mm. The main groove 100 and the inner circumferential groove 140 are collectively referred to as a "circumferential groove". That is, a "circumferential groove" is a groove with a groove width (maximum groove width) exceeding 2 mm that extends in the circumferential direction of the tire, and in this embodiment, it includes the main groove 100 and the inner circumferential groove 140.

[0024] In relation to the circumferential grooves described above, the circumferential sipes 150 are grooves with a groove width of 2 mm or less. In other words, the circumferential sipes 150 are not included in the circumferential grooves.

[0025] Here, grooves with a width of 2 mm or less, called sipes, are very narrow, and the effect they have on the tire 1 is different from that of other grooves, so it is desirable to treat them separately. Therefore, in this specification, sipes are treated separately from other grooves (main grooves, narrow grooves, slits). Accordingly, circumferential sipes 150 are not included in circumferential grooves.

[0026] In this specification, sipes are classified as grooves with a width of 2 mm or less, regardless of the direction in which they extend. However, for the sake of explanation, sipes extending in the circumferential direction are referred to as "circumferential sipes." In this embodiment, the tread surface 37 is provided with circumferential sipes 150, as well as a first sipe 310, a second sipe 320, a third sipe 330, a fourth sipe (closed sipe) 350, a fifth sipe 380, and a sixth sipe 390, which will be described later.

[0027] Furthermore, the tread surface 37 of this embodiment is provided with grooves referred to as "slits," which have a groove width exceeding 2 mm and a component that extends in a direction intersecting the circumferential grooves. The tread surface 37 of this embodiment is provided with a second rib closing slit 520 and a third rib closing slit 530 as slits.

[0028] The tread pattern 38 of the tread surface 37 of this embodiment will be described in more detail below, for each circumferential groove (110, 120, 130, 140) and rib 200.

[0029] Multiple ribs 200 are separated by circumferential grooves (110, 120, 130, 140) and extend continuously in a rib-like manner around the entire circumference in the circumferential direction of the tire. Multiple ribs 200 are partitioned in the axial direction of the tire, and each of the circumferential grooves (110, 120, 130, 140) is positioned between the ribs 200. That is, both the multiple ribs 200 and the circumferential grooves (110, 120, 130, 140) extend in an annular shape along the circumferential direction of the tire. In the following description, the width direction of the circumferential grooves (110, 120, 130, 140) and ribs 200 is the same direction as the axial direction of the tire, and the width of the circumferential grooves (110, 120, 130, 140) and ribs 200 refers to the dimension in the axial direction of the tire.

[0030] In this embodiment, the main grooves 100 extend along the tire circumferential direction C, in parallel to each other in the order of inner main groove 110, intermediate main groove 120, and outer main groove 130, from the inside in the vehicle width direction to the outside in the vehicle width direction, in the axial direction of the tire.

[0031] The inner main groove 110 is positioned inward in the vehicle width direction from the tire equator S2 and the intermediate main groove 120 when the tire 1 is mounted on the vehicle. The inner main groove 110 is the innermost main groove in the vehicle width direction.

[0032] An inner circumferential sloped portion 111 is provided on the edge of the inner main groove 110. The inner circumferential sloped portion 111 is provided in a chamfered manner on the edge of the groove wall on the inner side in the vehicle width direction of the inner main groove 110, that is, on the edge of the connection portion between the inner main groove 110 and the fifth rib 250. The inner circumferential sloped portion 111 is a slope inclined with respect to the tire radial direction, where the groove width widens toward the outer side in the tire radial direction, and extends in the tire circumferential direction C. The depth of the inner circumferential sloped portion 111 in the tire radial direction (depth from the surface of the fifth rib 250) can be, for example, 0.5 mm or more and 2.0 mm or less. The width of the inner circumferential sloped portion 111 in the tire axial direction can be 0.5 mm or more and 2.0 mm or less. The depth of the inner circumferential sloped portion 111 in the tire radial direction and the width in the tire axial direction are constant regardless of location. Note that "constant" does not mean strictly identical values; dimensional variations due to manufacturing tolerances, etc., are acceptable.

[0033] Since the inner main groove 110 is provided with the inner circumferential slope portion 111 described above, as shown in Figure 3, the groove width B110 of the inner main groove 110 is the width including the width of the inner circumferential slope portion 111.

[0034] The intermediate main groove 120 is positioned slightly inward in the vehicle width direction from the tire equator S2 when the tire 1 is mounted on the vehicle. The intermediate main groove 120 may also be positioned in a position that overlaps with the tire equator S2, or it may be positioned slightly outward in the vehicle width direction from the tire equator S2.

[0035] An intermediate circumferential sloped portion 121 is provided on the edge of the intermediate main groove 120. The intermediate circumferential sloped portion 121 is provided in a chamfered manner on the edge of the groove wall on the inner side in the vehicle width direction of the intermediate main groove 120, that is, on the edge of the connection portion between the intermediate main groove 120 and the fourth rib 240. The intermediate circumferential sloped portion 121 is a slope inclined with respect to the tire radial direction, where the groove width widens toward the outer side in the tire radial direction, and extends in the tire circumferential direction C. The depth of the intermediate circumferential sloped portion 121 in the tire radial direction (depth from the surface of the fourth rib 240) can be, for example, 0.5 mm or more and 2.0 mm or less. The width of the intermediate circumferential sloped portion 121 in the tire axial direction can be 0.5 mm or more and 2.0 mm or less. The depth of the intermediate circumferential sloped portion 121 in the tire radial direction and the width in the tire axial direction are constant regardless of location. Note that "constant" does not mean strictly identical values; dimensional variations due to manufacturing tolerances, etc., are acceptable.

[0036] Since the intermediate main groove 120 is provided with the intermediate circumferential slope portion 121, as shown in Figure 3, the groove width B120 of the intermediate main groove 120 is the width including the width of the intermediate circumferential slope portion 121.

[0037] The outer main groove 130 is positioned outside the tire equator S2 and the intermediate main groove 120 in the vehicle width direction when the tire 1 is mounted on the vehicle. The outer main groove 130 is the outermost main groove in the vehicle width direction. In this embodiment, the outer main groove 130 is adjacent to the outer side of the first rib 210 in the vehicle width direction.

[0038] An outer width-decreasing circumferential slope portion 450 is provided on the edge of the outer main groove 130. The outer width-decreasing circumferential slope portion 450 is provided in a chamfered manner on the edge of the groove wall on the outer side in the vehicle width direction of the outer main groove 130, that is, on the edge of the connection portion between the outer main groove 130 and the second rib 220. The outer width-decreasing circumferential slope portion 450 is a slope inclined with respect to the tire radial direction, where the groove width widens toward the outer side in the tire radial direction, and extends in the tire circumferential direction C. The width in the tire axial direction and the depth in the tire radial direction of the outer width-decreasing circumferential slope portion 450 change depending on the position in the tire circumferential direction C.

[0039] The depth of the outer width-decreasing circumferential slope portion 450 in the tire radial direction (depth from the surface of the second rib 220) can be, for example, 0.3 mm to 1.0 mm at the point of minimum depth, and 3.5 mm to 6.0 mm at the point of maximum depth. However, it is desirable that the maximum depth of the outer width-decreasing circumferential slope portion 450 in the tire radial direction be shallower than the depth of the second rib closing slit 520 in the tire radial direction, as described later. This is because a shallower outer width-decreasing circumferential slope portion 450 than the second rib closing slit 520 increases the block rigidity of the second rib 220, suppressing movement in that part, which in turn enables uniform contact and contributes to suppressing uneven wear. Furthermore, the width of the outer width-decreasing circumferential slope portion 450 in the direction perpendicular to its extension can be, for example, 0.5 mm to 1.5 mm at the point of minimum width, and 2.5 mm to 7.0 mm at the point of maximum depth.

[0040] Since the outer main groove 130 is provided with the outer width-decreasing circumferential slope portion 450 described above, as shown in Figures 3 and 4, the groove width B130 of the outer main groove 130 is the width including the width of the outer width-decreasing circumferential slope portion 450. As mentioned earlier, in the case of a groove whose groove width changes with position, the groove width at the part with the maximum width is treated as the groove width of that groove. Therefore, the groove width B130 of the outer main groove 130 is the width at the position where the width of the outer width-decreasing circumferential slope portion 450 in the tire axial direction is maximum.

[0041] By providing slopes on the edges of each of the main grooves, drainage is improved, and uneven wear of the corresponding ribs 200 (fifth rib 250, fourth rib 240, second rib 220) can be suppressed. Furthermore, for the outer width-variable circumferential slope section 450, the design is improved and drainage is enhanced by providing sections with relatively large width and depth, and by gradually decreasing the width and depth (hereinafter also referred to as "gradual change"), the effect of suppressing uneven wear is maintained, and the contact area is prevented from decreasing. Thus, it is possible to achieve both handling stability on dry roads and handling stability on wet roads.

[0042] Furthermore, it is desirable that the ratio of the depth of the inner circumferential slope portion 111 to the maximum depth of the outer width-decreasing circumferential slope portion 450 be between 5% and 40%. By setting the ratio of the depth of the inner circumferential slope portion 111 to the maximum depth of the outer width-decreasing circumferential slope portion 450 within the above range, drainage on the outer side in the vehicle width direction can be improved.

[0043] The groove width B110 of the inner main groove 110, the groove width B120 of the intermediate main groove 120, and the groove width B130 of the outer main groove 130 can each be set as appropriate, but their widths are, for example, about 5 mm to 15 mm and their depths are about 6 mm to 18 mm, but are not limited to these. The groove widths B110, B120, and B130 may all have different widths and depths, or some may be the same. In this embodiment, the groove width B120 of the intermediate main groove 120 is wider than the groove width B110 of the inner main groove 110, and the groove width B130 of the outer main groove 130 is even wider than the groove width B120 of the intermediate main groove 120. Specifically, in this implemented diameter configuration, the groove width B110 of the inner main groove 110 is 7.8 mm, the groove width B120 of the intermediate main groove 120 is 8.3 mm, and the groove width B130 of the outer main groove 130 is 11.62 mm. This improves drainage on the outer side in the vehicle width direction, where drainage tends to be poor in asymmetrical tires. In addition, since the groove width B120 of the intermediate main groove 120 is wider than the groove width B110 of the inner main groove 110, drainage in the center is improved, contributing to improved handling stability.

[0044] Here, we will explain why drainage performance tends to be poor on the outer side in the vehicle width direction in asymmetrical tires. Generally, the camber angle of a vehicle is set to negative camber, so the contact length on the inner side in the vehicle width direction is longer. Therefore, in asymmetrical pattern tires, more grooves are provided on the inner side in the vehicle width direction to improve drainage performance, and fewer grooves are provided on the outer side in the vehicle width direction to increase rigidity and improve handling stability. For this reason, it is expected that drainage performance will be poor on the outer side in the vehicle width direction in asymmetrical tires. Therefore, in tire 1 of this embodiment, the groove width of the circumferential groove on the outer side in the vehicle width direction, where the contact length is shortened due to the negative camber of the vehicle, is made larger than the groove width of the circumferential groove on the inner side in the vehicle width direction, thereby improving drainage performance on the outer side, where it is expected that drainage performance will be poor.

[0045] The inner circumferential groove 140 is adjacent to the inner side in the vehicle width direction of the first rib 210 (described later) and adjacent to the outer side in the vehicle width direction of the third rib 230 (described later). The inner circumferential groove 140 is formed by a slope inclined with respect to the tire radial direction, with the groove width widening toward the outer side in the tire radial direction, and extends in the tire circumferential direction C. The width in the tire axial direction and the depth in the tire radial direction of the inner circumferential groove 140 change depending on the position in the tire circumferential direction C. The third rib closing slit 530 (described later) is arranged overlapping the inner circumferential groove 140, but since its shape is recessed toward the inner side in the tire radial direction and extends continuously along the tire circumferential direction, it is treated as a circumferential groove.

[0046] The inner circumferential groove 140 has a shape obtained by rotating the outer width-decreasing circumferential slope portion 450 by 180 degrees when viewed from the normal direction of the tread surface 37 in the tire-unfolded state. That is, the direction in which the width and depth are from the wider side to the narrower side is reversed between the inner circumferential groove 140 and the outer width-decreasing circumferential slope portion 450. In the state shown in Figure 3, the side with the wider width and depth is the lower side of the paper for the inner circumferential groove 140, but the upper side of the paper for the outer width-decreasing circumferential slope portion 450. As described above, the tread pattern 38 of the tire 1 of this embodiment is asymmetrical, and the direction of rotation during driving differs depending on the mounting position on the vehicle. However, since the direction in which the width and depth are from the wider side to the narrower side is reversed between the inner circumferential groove 140 and the outer width-decreasing circumferential slope portion 450, no matter which direction the tire 1 rotates, there will be no significant change in the drainage characteristics, and stable drainage performance can be obtained.

[0047] The radial depth of the inner circumferential groove 140 (depth from the surface of the first rib 210) can be, for example, 0.3 mm to 1.0 mm at the point of minimum depth, and 3.5 mm to 6.0 mm at the point of maximum depth. However, it is desirable that the maximum radial depth of the inner circumferential groove 140 be shallower than the radial depth of the third rib closing slit 530, which will be described later. This is because a shallower inner circumferential groove 140 than the third rib closing slit 530 increases the rigidity of the third rib 230, enables uniform contact with the ground, and contributes to suppressing uneven wear. Furthermore, the width of the inner circumferential groove 140 in the direction perpendicular to its extension can be, for example, 0.5 mm to 1.5 mm at the point of minimum width, and 2.5 mm to 7.0 mm at the point of maximum width. In this embodiment, the width of the inner circumferential groove 140 in the direction perpendicular to its extension is 1.00 mm at its narrowest point and 3.58 mm at its widest point. Since the width of the inner circumferential groove 140 in the direction perpendicular to its extension varies depending on the position C in the tire circumferential direction, the width B140 of the inner circumferential groove 140 (see Figure 4) is defined as the portion with the widest width, as shown in Figure 4. Therefore, in this embodiment, the width B140 of the inner circumferential groove 140 is 3.58 mm. The reason for making the width of the inner circumferential groove 140 narrower than the width of the outer main groove 130 is to increase the rigidity near the center (center portion) in the tire axial direction and improve initial response.

[0048] Furthermore, the inner circumferential groove 140 is a narrow groove with a narrower groove width than any of the main grooves 100 (110, 120, 130). In this embodiment, as mentioned above, the groove width B110 of the inner main groove 110 is 7.8 mm, the groove width B120 of the intermediate main groove 120 is 8.3 mm, and the groove width B130 of the outer main groove 130 is 11.62 mm, whereas the width B140 of the inner circumferential groove 140 is 3.58 mm, meaning that the inner circumferential groove 140 has a narrower groove width than any of the main grooves 100.

[0049] In this embodiment, the ribs 200 include a first rib 210, a second rib 220, a third rib 230, a fourth rib 240, and a fifth rib 250. These ribs 200 are arranged in parallel in the tire circumferential direction C, from the inside in the vehicle width direction to the outside in the vehicle width direction, in the order of fifth rib 250, fourth rib 240, third rib 230, first rib 210, and second rib 220, in the tire axial direction.

[0050] The first rib 210 is positioned inward in the vehicle width direction from the outer main groove 130 and offset outward in the vehicle width direction from the tire equator S2. In this embodiment, the first rib 210 is positioned between the outer main groove 130 and the inner circumferential groove 140. In this embodiment, the first rib 210 is positioned outward in the vehicle width direction from the tire equator S2, but this is not the only case. For example, even if the first rib is positioned in a position that coincides with the tire equator S2, it is sufficient if its center in the tire width direction is offset outward in the vehicle width direction. By positioning the first rib 210, which is inward in the vehicle width direction from the outer main groove 130, and offset outward in the vehicle width direction from the tire equator S2, only the outer main groove 130 and the second rib 220 (described later) are positioned outward from the first rib 210 in the vehicle width direction. This improves drainage on the outer side in the vehicle width direction, where drainage tends to be poor in asymmetrical tires, with the outer main groove 130, and ensures rigidity with the wide second rib 220, thereby improving handling stability.

[0051] Furthermore, it is desirable that the center of the first rib 210 (the center of the width of the first rib 210 in the tire axial direction) be offset by 10% to 20% outward in the vehicle width direction relative to the contact width of the tread surface from the tire equator S2. Here, the contact width shall be determined from the contact pattern when tire 1 is in contact with the ground under normal load. If the amount by which the center of the first rib 210 is offset outward in the vehicle width direction relative to the contact width of the tread surface from the tire equator S2 is less than 10%, the effect of improving handling stability will be reduced, and the second rib 220 (the outermost rib in the vehicle width direction) will become too large, resulting in higher impact noise. Also, if the amount by which the center of the first rib 210 is offset outward in the vehicle width direction relative to the contact width of the tread surface from the tire equator S2 is 20% or more, the contact area on the outer side in the width direction will decrease, resulting in reduced rigidity.

[0052] Figure 6 shows the contact pattern when the tire 1 of this embodiment is placed on the ground under a normal load. In the figure, the line S2 indicates the tire equator S2, and the line C210 indicates the center of the first rib 210. The position of the center of the first rib 210 (C210), determined from the contact pattern shown in Figure 6, is located at a position shifted 15% to 35% outward in the vehicle width direction relative to the contact width of the tread surface from the tire equator S2.

[0053] Furthermore, among the circumferential grooves, it is desirable that the groove width of the outer main groove 130 adjacent to the outer side in the vehicle width direction of the first rib 210 is greater than the groove width of the inner circumferential groove 140 adjacent to the inner side in the vehicle width direction of the first rib 210. This makes it possible to improve the drainage performance on the outer side in the vehicle width direction, which tends to have poor drainage performance in asymmetrical tires. In this embodiment, the groove width of the outer main groove 130 is greater than the groove width of the inner circumferential groove 140.

[0054] Furthermore, the groove width B130 of the outer main groove 130 is preferably between 6.0 mm and 18.0 mm. By ensuring a wide outer width-variable circumferential slope 450, the contact pressure can be distributed, contributing to the suppression of uneven wear on the shoulder.

[0055] Furthermore, the first rib 210 is provided with a fourth sipe (closing sipe) 350. In the unfolded view shown in Figures 3 and 4, the fourth sipe 350 is a sipe with a groove width of 2 mm or less that extends diagonally in a straight line at an angle to the intermediate main groove 120. The fourth sipe 350 is a closing sipe in which one end on the side closer to the inner circumferential groove 140 terminates and closes without reaching the inner circumferential groove 140. The other end of the fourth sipe 350 on the side of the outer main groove 130 is connected to and communicates with the outer main groove 130. The fourth sipe 350 is also positioned on the extension of the second rib closing slit 520 and the third rib closing slit 530, which will be described later. The groove width and groove depth of the fourth sipe 350 do not need to be more than 2.0 mm, but for manufacturing reasons, it is desirable that they be 1.0 mm or more. The groove depth of the fourth sipe 350 can be, for example, 4.5 mm or more and 7.0 mm or less.

[0056] The second rib 220 is positioned outside the outer main groove 130 in the vehicle width direction and is located between the outer main groove 130 and the outer shoulder 40B. When the tire 1 is mounted on the vehicle, the second rib 220 is positioned outside in the vehicle width direction. The outer end of the second rib 220 in the vehicle width direction smoothly continues to the outer shoulder 40B. The inner end of the second rib 220 in the vehicle width direction is adjacent to the outer main groove 130. The width of the second rib 220 is the widest of the multiple ribs 200. That is, the width of the second rib 220 is wider than the width of the first rib 210, the third rib 230, the fourth rib 240, and the fifth rib 250. This increases the rigidity on the outer side in the vehicle width direction and improves handling stability.

[0057] In this embodiment, the outer end and inner end of the tire 1 in the tire width direction are gently curved in the tire axial cross-section along the shape of the shoulder. Therefore, the width of the second rib 220 and the width of the fifth rib 250 vary depending on whether the outer end or the inner end in the tire width direction is located. Accordingly, the width of the second rib 220 and the width of the fifth rib 250 are determined based on the contact pattern when the tire 1 shown in Figure 6 is placed on the ground under a normal load.

[0058] The second rib 220 is provided with a second rib closing slit 520, a circumferential sipe 150, a fifth sipe 380, and a sixth sipe 390.

[0059] Figure 7 is a cross-sectional view of the second rib closure slit 520, cut at the position of arrow EE in Figure 4, in a direction perpendicular to the extension direction of the second rib closure slit 520. The second rib closure slit 520 has a groove bottom 521, a first wall surface 522, and a second wall surface 523, and extends in a direction intersecting the tire circumferential direction C. More specifically, in the unfolded views shown in Figures 3 and 4, the second rib closure slit 520 extends diagonally and linearly at an angle to the outer main groove 130.

[0060] The groove bottom 521 is recessed inward in the tire radial direction from the second rib 220, forming the bottom of the second rib closing slit 520, and has a shape that offsets the second rib 220. The width B521 of the groove bottom 521 is greater than 2.0 mm and less than 4.0 mm. The depth of the groove bottom 521 is equal to the depth D520 of the second rib closing slit 520, and this depth D520 can be exemplified as being between 4.5 mm and 7.0 mm, but is shallower than the groove depth of the main groove 100 (inner main groove 110, intermediate main groove 120, outer main groove 130).

[0061] The first wall surface 522 extends radially outward from the groove bottom 521. In the cross-section oriented perpendicular to the extension direction of the second rib closing slit 520 shown in Figure 7, in this embodiment, the first wall surface 522 is approximately perpendicular to the groove bottom 521.

[0062] The second wall surface 523 extends radially outward from the opposite side of the groove bottom 521 from the first wall surface 522. Furthermore, the second wall surface 523 is composed of a more inclined surface than the first wall surface 522. That is, with respect to the groove bottom 521, the angle between the groove bottom 521 and the first wall surface 522 is approximately 90 degrees, while the angle between the groove bottom 521 and the second wall surface 523 is greater than 90 degrees. As shown in Figure 7, the second wall surface inclination angle θ520 is defined in a cross-section obtained by cutting the second rib closing slit 520 in a direction perpendicular to the extension direction of the second rib closing slit 520. The second wall inclination angle θ520 is the angle between the line segment connecting the intersection of the second wall surface 523 with the groove bottom 521 to the end of the second wall surface 523 on the radially outer side of the tire, and the line segment connecting the intersection of the first wall surface 522 with the groove bottom 521 to the end of the first wall surface 522 on the radially outer side of the tire. This second wall inclination angle θ520 is preferably between 25 degrees and 60 degrees. That is, the angle between the line segment connecting the intersection of the second wall surface 523 with the groove bottom 521 to the end of the second wall surface 523 on the radially outer side of the tire, and the groove bottom 521 is preferably between 115 degrees and 150 degrees. Because the angle θ520 is a relatively small angle as described above, the second rib closing slit 520 can effectively function as a groove. Therefore, it has a larger groove width than conventional sipes or grooves alone that do not have an inclined surface like the second wall surface 523, and it can secure a water flow path until the end of wear, improving drainage.

[0063] The width B523 of the second wall surface 523 can be, for example, 0.5 mm or more and 1.5 mm or less at the narrowest part, and 2.5 mm or more and 7.0 mm or less at the widest part.

[0064] The second wall surface 523 has a constant depth, and when viewed from the outside in the tire radial direction, its width B523 gradually changes along the direction in which the second rib closing slit 520 extends. Specifically, when viewed from the inside in the vehicle width direction toward the outside in the vehicle width direction, the width of the second wall surface 523 gradually narrows along the direction in which the second rib closing slit 520 extends. Also, when viewed from the outside in the tire radial direction, the width B523 of the second wall surface 523 includes a portion that is wider than the width of the groove bottom 521. The inside end of the second rib closing slit 520 in the vehicle width direction is connected to and communicates with the outer main groove 130.

[0065] In other words, the groove width on one end of the second rib closure slit 520 that communicates with the outer main groove 130 is larger than the groove width on the other end that is closed. By increasing the width on the side connected to the outer main groove 130, water that has entered the outer main groove 130 can be easily discharged into the second rib closure slit 520. The groove width of the second rib closure slit 520 does not have to be any particular shape as long as it increases toward the open end (outer main groove 130 side), it may increase in a stepped manner, gradually increase, or the groove wall may curve as it gradually increases. In addition, the orientation of the first wall surface 522 and the second wall surface 523 of the second rib closure slit 520 is aligned in the circumferential direction of the tire.

[0066] One end of the second rib closure slit 520 on the inside in the vehicle width direction is connected to and communicates with the outer main groove 130, but the other end on the outside in the vehicle width direction terminates and closes off before reaching the outer shoulder 40B. This ensures drainage while suppressing a decrease in the rigidity of the second rib 220 on the outside in the vehicle width direction, thereby improving handling stability.

[0067] The circumferential sipe 150 is a groove with a width of 2 mm or less that extends along the circumferential direction of the tire. The circumferential sipe 150 intersects with the second rib closing slit 520. The depth of the circumferential sipe 150 can be, for example, shallower than the main groove. Also, the width of the circumferential sipe 150 in the tire axial direction can be, for example, between 0.5 mm and 2.0 mm.

[0068] Furthermore, in the tire 1 of this embodiment, the width of the groove bottom 521 of the second rib closing slit 520, which is located circumferentially outward from the circumferential sipe 150, is narrower than the width of the groove bottom 521 of the second rib closing slit 520, which is located circumferentially inward from the circumferential sipe 150. This suppresses a decrease in the rigidity of the second rib 220 on the outer side in the vehicle width direction, thereby improving handling stability. In addition, the width of the groove bottom 521 of the second rib closing slit 520 is narrower than the groove width of the circumferential sipe 150 when it is circumferentially outward from the circumferential sipe 150, and wider than the groove width of the circumferential sipe 150 when it is circumferentially inward from the circumferential sipe 150.

[0069] In the unfolded view shown in Figures 3 and 4, the fifth sipe 380 extends approximately in the direction of the tire axis, but is slightly inclined with respect to the tire axis and extends in a straight line. The inner end of the fifth sipe 380 in the vehicle width direction communicates with the circumferential sipe 150, and the outer end in the vehicle width direction communicates with the outer end in the tire axis direction via the end groove 381. The end groove 381 communicates with the fifth sipe 380 and the outer end in the tire axis direction, has a depth of 1 mm or less, and is wider toward the outer side in the tire axis direction.

[0070] The groove width of the fifth sipe 380 may be 2.0 mm or less, but it is preferable that it be 1.0 mm or more. The groove depth of the fifth sipe 380 can be, for example, 3.0 mm to 7.0 mm.

[0071] In the unfolded views shown in Figures 3 and 4, the sixth sipe 390 extends approximately in the direction of the tire axis, but is slightly inclined with respect to the tire axis and extends in a straight line. The inner end of the sixth sipe 390 in the vehicle width direction is located near the second rib closing slit 520, and the outer end in the vehicle width direction communicates with the outer end in the tire axis direction via the end groove 391. The end groove 391 communicates with the sixth sipe 390 and the outer end in the tire axis direction, has a depth of 1 mm or less, and is wider in the direction of the outer end in the tire axis direction.

[0072] The groove width of the sixth sipe 390 may be less than 2.0 mm, but it is preferable that it be 1.0 mm or larger. The groove depth of the sixth sipe 390 can be, for example, between 3.0 mm and 7.0 mm.

[0073] The third rib 230 is located outside the inner main groove 110 in the vehicle width direction, and is adjacent to the inner side of the inner circumferential groove 140 in the vehicle width direction, and is located where the tire equator S2 passes. The third rib 230 is provided with a third rib closing slit 530.

[0074] Figure 8 is a cross-sectional view of the third rib closure slit 530, cut at the position indicated by arrow DD in Figure 4, in a direction perpendicular to the extension direction of the third rib closure slit 530. The third rib closure slit 530 has a groove bottom 531, a first wall surface 532, and a second wall surface 533, and extends in a direction intersecting the tire circumferential direction C. More specifically, in the unfolded views shown in Figures 3 and 4, the third rib closure slit 530 extends diagonally and linearly at an angle to the intermediate main groove 120.

[0075] The groove bottom 531 is recessed inward in the tire radial direction from the third rib 230, forming the bottom of the third rib closing slit 530, and has a shape that offsets the third rib 230. The groove bottom 531 has a width B531 of 2.0 mm or less, more preferably less than 1.5 mm, but it is desirable that it be 0.8 mm or more. The depth of the groove bottom 531 is the same as the depth D530 of the third rib closing slit 530, and this depth D530 can be exemplified as 4.5 mm to 7.0 mm, but is shallower than the groove depth of the main groove 100 (inner main groove 110, intermediate main groove 120, outer main groove 130).

[0076] The first wall surface 532 extends radially outward from the groove bottom 531. In the cross-section perpendicular to the extension direction of the third rib closing slit 530 shown in Figure 8, in this embodiment, the first wall surface 532 is approximately perpendicular to the groove bottom 531.

[0077] The second wall surface 533 extends radially outward from the opposite side of the groove bottom 531 from the first wall surface 532. Furthermore, the second wall surface 533 is composed of a more inclined surface than the first wall surface 532. That is, with respect to the groove bottom 531, the angle between the groove bottom 531 and the first wall surface 532 is approximately 90 degrees, while the angle between the groove bottom 531 and the second wall surface 533 is greater than 90 degrees. As shown in Figure 8, the inclination angle θ530 of the second wall surface is defined in a cross-section obtained by cutting the third rib closing slit 530 in a direction perpendicular to the extension direction of the third rib closing slit 530. The second wall inclination angle θ530 is the angle between the line segment connecting the intersection of the second wall 533 with the groove bottom 531 to the end of the second wall 533 on the radially outer side of the tire, and the line segment connecting the intersection of the first wall 532 with the groove bottom 531 to the end of the first wall 532 on the radially outer side of the tire. This second wall inclination angle θ530 is preferably between 10 degrees and 40 degrees. That is, the angle between the line segment connecting the intersection of the second wall 533 with the groove bottom 531 to the end of the second wall 533 on the radially outer side of the tire, and the groove bottom 531, is preferably between 100 degrees and 130 degrees. Because the angle θ530 is a relatively small angle as described above, the third rib closing slit 530 can effectively function as a groove. Therefore, it has a larger groove width than conventional sipes or grooves alone that do not have an inclined surface like the second wall 533, and it can secure a water flow path until the end of wear, improving drainage.

[0078] The width B533 of the second wall surface 533 can be, for example, 0.5 mm or more and 1.5 mm or less at the narrowest part, and 2.5 mm or more and 7.0 mm or less at the widest part.

[0079] The second wall surface 533 has a constant depth, and when viewed from the outside in the tire radial direction, its width B533 gradually changes along the direction in which the third rib closing slit 530 extends. Specifically, when viewed from the inside in the vehicle width direction toward the outside in the vehicle width direction, the width of the second wall surface 533 gradually widens along the direction in which the third rib closing slit 530 extends. Also, when viewed from the outside in the tire radial direction, the width B533 of the second wall surface 533 includes a portion that is wider than the width of the groove bottom 531. The outer end of the third rib closing slit 530 in the vehicle width direction is connected to and communicates with the inner circumferential groove 140.

[0080] In other words, the groove width on one end of the third rib closure slit 530 that communicates with the inner circumferential groove 140 is larger than the groove width on the other end that is closed. By increasing the width on the side connected to the inner circumferential groove 140, water that has entered the inner circumferential groove 140 can be easily discharged into the third rib closure slit 530. The groove width of the third rib closure slit 530 does not have to be any particular shape as long as it increases toward the open end (the side with the inner circumferential groove 140), and it may increase in a stepped manner, gradually increase, or gradually increase while the groove wall curves.

[0081] Furthermore, the orientation of the first wall surface 532 and the second wall surface 533 of the third rib closure slit 530 is aligned in the circumferential direction of the tire. The orientation of the first wall surface 522 and the second wall surface 523 of the second rib closure slit 520 is opposite to the orientation of the first wall surface 532 and the second wall surface 533 of the third rib closure slit 530. This suppresses changes in drainage characteristics and traction characteristics depending on the direction of tire rotation.

[0082] One end of the third rib closure slit 530, on the outer side in the vehicle width direction, is connected to and communicates with the inner circumferential groove 140, but the other end, on the inner side in the vehicle width direction, terminates and closes off before reaching the intermediate main groove 120. Since the third rib closure slit 530 does not communicate with the intermediate main groove 120, the collapse of the block due to wiping is suppressed, and the rigidity of the third rib 230 can be ensured. Therefore, while ensuring drainage performance, the reduction in rigidity of the third rib 230 can be suppressed, and steering stability can be improved.

[0083] Furthermore, if we consider the third rib closure slit 530 and the second rib closure slit 520 as width-expanding grooves having similar functions, the multiple width-expanding grooves are arranged such that the direction in which the second wall surface (inclined surface) is positioned alternates in the circumferential direction of the tire. This arrangement suppresses changes in drainage characteristics and traction characteristics depending on the direction of tire rotation.

[0084] Furthermore, by providing the third rib closure slit 530 in the third rib 230, the straight-line response can be improved.

[0085] The second rib closure slit 520 and the third rib closure slit 530 are positioned on their respective extensions, and the fourth sipe 350 is also positioned on the extensions of the second rib closure slit 520 and the third rib closure slit 530. This allows deep, widthwise grooves to remain until the end of wear, scratching the road surface and contributing to improved traction.

[0086] In the tire 1 of this embodiment, the second wall surface 523 of the second rib closing slit 520 and the second wall surface 533 of the third rib closing slit 530 are both linear, i.e., substantially planar, in a cross-section perpendicular to the direction of groove extension, as illustrated in Figures 7 and 8. However, the specific shape of the second wall surface 523 of the second rib closing slit 520 and the second wall surface 533 of the third rib closing slit 530 is not limited to a flat inclined surface. For example, the second wall surface (second wall surface 523, 533) may be a curved surface with a convex shape directed outward in the tire radial direction. Alternatively, the second wall surface (second wall surface 523, 523) may be a curved surface with a concave shape directed inward in the tire radial direction.

[0087] The fourth rib 240 is positioned between the intermediate main groove 120 and the inner main groove 110. The fourth rib 240 is provided with a third sipe 330 and third sipe slopes 410 and 420.

[0088] In the unfolded view shown in Figure 3, the third sipe 330 extends diagonally at an angle to the inner main groove 110 and the intermediate main groove 120. Furthermore, the third sipe 330 is formed in a slightly curved arc shape.

[0089] The groove width of the third sipe 330 may be less than 2.0 mm, but it is preferable that it be 0.8 mm or more. The groove depth of the third sipe 330 can be, for example, 4.0 mm to 7.0 mm.

[0090] The inner end of the third sipe 330 in the vehicle width direction is in communication with the inner main groove 110. On the other hand, the outer end of the third sipe 330 in the vehicle width direction is a closed sipe that terminates and closes without communicating with the intermediate main groove 120. Therefore, the fourth rib 240 has a structure that is continuously connected around the entire circumference in the tire circumferential direction C. As a result, the intermediate main groove 120 is not connected, which suppresses block deformation due to wiping and ensures rigidity as a circumferential rib. Wiping refers to the deformation of the tread rubber along the tire width direction due to in-plane contraction force generated toward the center in the tire width direction as the tire makes contact with the road surface.

[0091] The third sipe bevels 410 and 420 are formed in a substantially chamfered shape on one edge of the third sipe 330, that is, on the edge of the connection portion between the third sipe 330 and the fourth rib 240. The third sipe bevels 410 and 420 are slopes inclined with respect to the tire radial direction, with the groove width widening toward the radially outward direction of the tire, and partially extend along the third sipe 330.

[0092] The inner ends of the third sipe slopes 410 and 420 in the vehicle width direction are in communication with the inner main groove 110. On the other hand, the outer ends of the third sipe slopes 410 and 420 in the vehicle width direction do not reach the intermediate main groove 120 and are not in communication with it.

[0093] The third sipe slope 410 and the third sipe slope 420 have different lengths. The outer end of the third sipe slope 410 in the vehicle width direction is located near the center of the fourth rib 240 in the tire axial direction. On the other hand, the outer end of the third sipe slope 420 in the vehicle width direction is located further outward in the vehicle width direction than the center of the fourth rib 240 in the tire axial direction, that is, further outward in the vehicle width direction than the outer end of the third sipe slope 410. Furthermore, the third sipe slope 410 and the third sipe slope 420 are arranged alternately in the tire circumferential direction C.

[0094] The depth of the third sipe slopes 410 and 420 in the tire radial direction (depth from the surface of the fourth rib 240) can be, for example, 2.0 mm or more and 3.5 mm or less. The width of the third sipe slopes 410 and 420 in the direction perpendicular to the extension direction can be 1.5 mm or more and 3.5 mm or less. The depth of the third sipe slopes 410 and 420 in the tire radial direction and the width perpendicular to the extension direction are constant regardless of location. However, "constant" does not mean strictly identical values; dimensional variations due to manufacturing tolerances, etc., are permitted.

[0095] Furthermore, as described above, the third sipe 330 is partially provided with third sipe slopes 410 and 420. In the portion where these third sipe slopes 410 and 420 are provided, the groove width, including the width of the third sipe slopes 410 and 420, may exceed 2.0 mm. Therefore, if we classify the groove type by groove width as mentioned earlier, this portion could also be considered a slit. However, for the sake of ease of understanding, the entire portion is referred to here as the third sipe 330.

[0096] The fifth rib 250 is positioned between the inner main groove 110 and the inner shoulder 40A. When the tire 1 is mounted on the vehicle, the fifth rib 250 is positioned on the inner side in the vehicle width direction. The inner end of the fifth rib 250 in the vehicle width direction smoothly continues to the inner shoulder 40A. The fifth rib 250 is provided with a first sipe 310 and a second sipe 320.

[0097] In the unfolded view shown in Figure 3, the first sipe 310 extends approximately in the direction of the tire axis, but is slightly inclined relative to the tire axis. Furthermore, the first sipe 310 is formed in a slightly curved arc shape. The inner end of the first sipe 310 in the vehicle width direction is near the inner shoulder 40A, and the outer end in the vehicle width direction communicates with the inner main groove 110. The groove width of the first sipe 310 may be less than 2.0 mm, but for manufacturing reasons, it is desirable to have a groove width of 1.0 mm or more. The groove depth of the first sipe 310 can be, for example, 4.5 mm to 7.0 mm.

[0098] In the unfolded view shown in Figure 3, the second sipe 320 appears to have a shape similar to the first sipe 310. That is, in the unfolded view shown in Figure 3, the second sipe 320 extends roughly in the direction of the tire axis, but it extends with a slight inclination relative to the tire axis. Furthermore, the second sipe 320 is formed in a slightly curved arc shape.

[0099] The second sipe 320 has its inner end in the vehicle width direction near the inner shoulder 40A and communicates with the outer end in the tire axial direction via the end groove 321. The end groove 321 communicates with the second sipe 320 and the outer end in the tire axial direction, has a depth of 1 mm or less, and is wider toward the outer side in the tire axial direction.

[0100] Furthermore, although the outer end of the second sipe 320 in the vehicle width direction does not reach the inner main groove 110, it communicates with the inner main groove 110 via the end groove 322. The end groove 322 communicates with the second sipe 320 and the inner main groove 110, has a depth of 1.8 mm to 3.0 mm, and is wider toward the inner side in the tire axial direction.

[0101] The groove width of the second sipe 320 may be less than 2.0 mm, but it is preferable that it be 0.8 mm or more. The groove depth of the second sipe 320 can be, for example, between 4.0 mm and 7.0 mm.

[0102] As described above, the inner side of the second sipe 320 in the vehicle width direction does not directly communicate with the outside, nor does the outer side of the second sipe 320 in the vehicle width direction directly communicate with the inner main groove 110. This prevents the fifth rib 250 from becoming unnecessarily rigid. On the other hand, the inner side of the second sipe 320 in the vehicle width direction communicates with the outside via the end groove 321, and communicates with the inner main groove 110 via the end groove 322. This ensures sufficient drainage and suppresses air pumping noise by ensuring an air passage.

[0103] Furthermore, as shown in Figure 3, the first sipe 310 and the second sipe 320 are arranged alternately in the tire circumferential direction C. This allows for uniform rigidity.

[0104] In this embodiment, the widths of the fifth rib 250 and the second rib 220 (the distance from the end of the design of each rib shape to the edge of the main groove) are greater than those of the first rib 210, the third rib 230, and the fourth rib 240, with the width of the fifth rib 250 being slightly smaller than that of the second rib 220. The width of the fifth rib 250 is, for example, about 30 mm to 60 mm, and the width of the second rib 220 is, for example, about 40 mm to 70 mm, but is not limited to these. The width of the fifth rib 250 may be greater than that of the second rib 220, or their widths may be the same.

[0105] The tire 1 according to the embodiment described above provides the following effects.

[0106] (1) The tire 1 according to this embodiment is a tire 1 for which the mounting direction is specified, and comprises a plurality of circumferential grooves (110, 120, 130, 140) having a groove width exceeding 2 mm and extending in the circumferential direction of the tire, and a plurality of ribs (210, 220, 230, 240, 250) that are separated by the circumferential grooves (110, 120, 130, 140) and extend continuously in a rib-like manner around the entire circumference in the circumferential direction of the tire, wherein the plurality of circumferential grooves (110, 120, 130, 140) have a groove width of 3 mm or less The tire has a plurality of main grooves (110, 120, 130) on top, and a first rib 210 which is located inward in the vehicle width direction from the outer main groove 130, which is the outermost of the main grooves (110, 120, 130) in the vehicle width direction, and which is offset outward in the vehicle width direction from the tire equator S2, and the groove width of the outer main groove 130 adjacent to the outer side of the first rib 210 in the vehicle width direction from the circumferential grooves (110, 120, 130, 140) is greater than the groove width of the inner circumferential groove 140 adjacent to the inner side of the first rib 210 in the vehicle width direction.

[0107] As a result, only the outer main groove 130 and a wider rib (second rib 220 in the embodiment) are arranged on the outer side in the vehicle width direction beyond the first rib 210, thereby improving handling stability and drainage.

[0108] (2) The tire described in (1) further comprises a second rib 220 positioned outside the outer main groove (130) in the vehicle width direction, and a third rib 230 adjacent to the inner side of the inner circumferential groove 140 in the vehicle width direction.

[0109] This improves initial responsiveness (primarily due to the effects of the first rib 210 and the third rib 230) and handling stability (primarily due to the effects of the second rib 220).

[0110] (3) A tire as described in (1) or (2), wherein the inner circumferential groove 140 has a groove width narrower than the main grooves (110, 120, 130).

[0111] This improves drainage performance on the outer side of asymmetrical tires, where drainage is typically expected to be inferior.

[0112] (4) In the tire described in (2), the third rib 230 is located on the tire equator S2.

[0113] This allows for a highly rigid rib configuration at the tire equator S2, and because the distance to the first rib 210 is also short, initial response performance can be improved.

[0114] In the tire described in (5)(2), the width of the second rib 220 is the widest of the multiple ribs (210, 220, 230, 240, 250).

[0115] This increases the rigidity on the outer side in the vehicle width direction, thereby improving handling stability.

[0116] In the tire described in (6)(2), the second rib 220 has a second rib closure slit 520 which extends in a direction intersecting the circumferential grooves (110, 120, 130, 140), with one end communicating with the circumferential groove (130) and the other end being closed. The third rib 230 has a third rib closure slit 530 which extends in a direction intersecting the circumferential grooves (110, 120, 130, 140), with one end communicating with the circumferential groove (140) and the other end being closed.

[0117] This allows for improved drainage while maintaining rib rigidity, thereby enhancing handling stability.

[0118] In the tire described in (7)(6), the second rib closure slit 520 and the third rib closure slit 530 are such that the groove width on one end communicating with the circumferential groove (130, 140) is greater than the groove width on the other end which is closed.

[0119] This makes it easier to discharge water that has entered the circumferential grooves into the second rib closure slit 520 and the third rib closure slit 530.

[0120] In the tire described in (8), (6), or (7), the second rib 220 has a circumferential sipe 150 with a groove width of 2 mm or less that extends in the circumferential direction, and the circumferential sipe 150 intersects with the second rib closing slit 520.

[0121] This makes it possible to improve drainage performance while suppressing a decrease in the rigidity of the second rib 220.

[0122] In the tire described in any of (9)(6) to (8), the second rib closure slit 520 and the third rib closure slit 530 are arranged on their respective extensions, and the first rib 210 is provided with a closure sipe with a groove width of 2 mm or less, which is closed at one end, on the extensions of the second rib closure slit 520 and the third rib closure slit 530.

[0123] By providing a closed sipe with one side closed, the blocks of the first rib 210 can be made more uniform, improving ground contact.

[0124] (10) In any of the tires described in (1) through (9), the groove width B130 of the outer main groove 130 is preferably 6.0 mm or more and 18.0 mm or less.

[0125] This allows for a wider outer width-variable circumferential slope 450 to be secured, distributing the ground pressure and contributing to the suppression of uneven wear on the shoulder.

[0126] (11) In the tire described in any of (1) to (9), the center of the first rib 210 is positioned offset from the tire equator S2 by 15% to 35% outward in the vehicle width direction with respect to the contact width of the tread surface.

[0127] This enhances the effectiveness of improving handling stability and drainage, while also reducing impact noise.

[0128] The present invention is not limited to the embodiments described above, and various modifications and changes are possible, all of which fall within the scope of this disclosure. [Explanation of symbols]

[0129] 1 tire 30 tread 36 Tread Rubber 37 Tread surface 38 Tread Pattern 40 Shoulder 40A Inner Shoulder 40B External Shoulder 100 Main groove 110 Inner main groove 111 Inner circumferential slope section 120 Intermediate main groove 121 Intermediate circumferential slope section 130 Outer main groove 140 Inner circumferential groove 150 circumferential sipes 200 ribs 210 First Rib 220 Second Rib 230 Third Rib 240 Fourth Rib 250 Fifth Rib 310 First Sipe 320 Second Sipe 321 End groove 322 End groove 330 Third Sipe 350 Fourth Sipe 380 Fifth Sipe 381 End groove 390 Sixth Sipe 391 End groove 410 Third sipe slope 420 Third sipe slope 450 Outside width deviation circumferential slope section 520 Second rib closure slit 521 Groove bottom 522 First Wall 523 Second Wall 530 Third rib occlusion slit 531 Groove bottom 532 First Wall 533 Second Wall

Claims

1. A tire for which the mounting direction is specified, A groove with a width exceeding 2 mm, comprising multiple circumferential grooves extending in the circumferential direction of the tire, A land area separated by the aforementioned circumferential grooves, comprising a plurality of ribs that extend continuously in a rib-like manner around the entire circumference in the tire circumferential direction, Equipped with, The aforementioned plurality of circumferential grooves include a plurality of main grooves with a groove width of 3 mm or more. It has a first rib that is located inward in the vehicle width direction from the outermost main groove of the main grooves, and is offset outward in the vehicle width direction from the tire equator, A tire in which, among the circumferential grooves, the groove width of the outer main groove adjacent to the outer side in the vehicle width direction of the first rib is greater than the groove width of the inner circumferential groove adjacent to the inner side in the vehicle width direction of the first rib.

2. In the tire according to claim 1, A second rib is positioned further outward in the vehicle width direction than the aforementioned outer main groove, A third rib adjacent to the inner side in the vehicle width direction of the aforementioned inner circumferential groove, A tire equipped with [a specific feature / feature].

3. In the tire according to claim 1 or claim 2, The inner circumferential groove is narrower in width than the main groove of the tire.

4. In the tire according to claim 2, The aforementioned third rib is located on the tire where the tire equator passes through.

5. In the tire according to claim 2, The width of the second rib is the widest of the multiple ribs in the tire.

6. In the tire according to claim 2, The second rib extends in a direction intersecting the circumferential groove, and has a second rib closing slit, which is a groove formed by one end communicating with the circumferential groove and the other end being closed. A tire having a third rib closing slit, which is a groove formed by the third rib extending in a direction intersecting the circumferential groove, with one end communicating with the circumferential groove and the other end being closed.

7. In the tire according to claim 6, In both the second rib closure slit and the third rib closure slit, the groove width on one end communicating with the circumferential groove is greater than the groove width on the other end that is closed.

8. In the tire according to claim 6 or claim 7, The second rib has circumferential sipes with a groove width of 2 mm or less that extend in the circumferential direction, and the circumferential sipes intersect with the closure slit of the second rib, in a tire.

9. In the tire according to claim 6 or claim 7, The second rib closure slit and the third rib closure slit are positioned on their respective extensions. The first rib is provided with a closed sipe with a groove width of 2 mm or less, which is closed at one end, on the extension of the second rib closing slit and the third rib closing slit.

10. In the tire according to claim 1 or claim 2, A tire in which the groove width of the outer main groove is 6.0 mm or more and 18.0 mm or less.

11. In the tire according to claim 1 or claim 2, A tire in which the center of the first rib is positioned offset from the tire equator by 15% to 35% outward in the vehicle width direction relative to the contact width of the tread surface.

Images