JP4785490B2 - Inclined groove structure of tire tread - Google Patents

Description

  The present invention relates to an inclined groove structure of a tire tread, and in particular, proposes a technique for realizing excellent wet drainage performance while ensuring high land portion rigidity.

  In order to improve the wet drainage performance of tires, it has been widely used in the past to improve the drainage performance of the tread tread area by increasing the number of grooves arranged on the tread tread or increasing the groove width. Has been done.

  However, according to such a conventional technique, the rigidity of the land portion decreases as the groove volume increases, which contributes to the occurrence of large uneven wear on the tread surface, as well as maneuvering. There was a problem that it contributed to a decrease in stability.

  The present invention advantageously solves such problems of the prior art with an inclined groove, and the object of the invention is, in particular, the streamline of the drainage water flow in the contact area of the tread surface. By paying attention to the above, it is an object to provide an inclined groove structure for a tire tread that achieves both high land rigidity and excellent wet drainage performance at a high level.

The inclined groove structure of a tire tread according to the present invention is inclined with respect to the tread circumferential direction of a tire including a tread portion, a pair of sidewall portions, and a bead portion continuous on the inner peripheral side of each sidewall portion. In the inclined groove that extends from the center part of the tread surface to the side part and contributes to the formation of the tread pattern, for example, the formation of the directional pattern that specifies the rotation direction of the tire, the middle of the extending direction of the inclined groove An inclined wall portion inclined at an acute angle with respect to the surface of the adjacent land portion is provided in the groove wall on either side of the side portion from the portion position, and the tread pattern of the inclined wall portion is developed. Increasing the visual width gradually from the intermediate position toward the side ,
A part or all of the region on the central side from the intermediate position in the extending direction of the inclined groove is also inclined at an acute angle with respect to the adjacent land surface on the central groove wall on either side of the inclined groove. Providing an inclined wall portion that increases the width of the inclined wall portion in a developed view of the tread pattern toward the center side,
The respective inclined wall portions described above are formed on opposite sides of each other with the groove bottom of the inclined groove therebetween .

  Here, the “intermediate portion position” in the extending direction of the inclined groove refers to a position included in a range of 20 to 80% of the extending direction.

  Here, the “width” of the inclined wall portion means a width measured in a direction orthogonal to the groove bottom center line of the inclined groove, and when the width “increases gradually”, the inclined wall portion In addition to the case where the adjacent side portion with the land portion extends in a straight line, a curved line or the like and gradually increases, the case where it gradually increases is also included.

  Here, the area where the width of the inclined wall portion measured in the direction perpendicular to the groove bottom center line is defined as “a part or all” of the central portion side region from the intermediate portion position. At the end part closer to the center than the part position, the width measured in the direction perpendicular to the groove bottom center line may gradually decrease toward the end edge, and This is because the inclined wall portion may not be formed at all.

Preferably, the contour shape of the inclined wall portion in a developed view of the tread pattern is substantially triangular.
Here, “substantially triangular” means a curved triangle in which one or more sides are curved and extend along or not along the bottom of the groove in relation to the extended form of the inclined groove. It is intended to include shapes.

And in the above structure in which the inclined wall portions are provided in the respective regions on the side portion side and the central side with respect to the intermediate portion position in the extending direction of the inclined groove, the two inclined wall portions are mutually connected. It can arrange | position as an adjacent attitude | position in the extension direction of an inclination groove | channel which has a vertex in the said intermediate part position.

  In any of the inclined wall portions as described above, the inclination angle with respect to the surface of the adjacent land portion is reduced as the width of the unfolded view increases. Can also be formed in a band shape within a predetermined range in the tire radial direction.

Preferably, the widening depression angle of the inclined wall portion in the unfolded view is 45 ° or less, and more preferably 30 ° or less.
The “widening depression angle” herein means an angle between the line segment extending along the groove bottom edge of the inclined groove and the boundary line segment of the inclined wall portion with the surface of the adjacent land portion. When at least one of the line segments is curved and extends, a straight line connecting the apex position of the inclined wall portion and the widest position of the inclined wall portion existing on the normal line to the groove bottom center line and / or The curved line segment is substituted by a straight line connecting the position where the normal line intersects the groove bottom side edge of the inclined wall portion and the apex position of the inclined wall portion.

  Here, the inclined wall portion provided in the region on the side portion side from the intermediate position in the extending direction of the inclined groove is formed on the tread tread surface and is continuously provided in the circumferential groove or the grounding end in the circumferential direction, or It is preferable to extend to the position where the lateral groove extending in the tread width direction is reached, that is, to extend to the reaching position with respect to the groove bottom portion of the inclined groove, or to end at the reaching position.

  Here, the “grounding end” means that the tire is mounted on the applicable rim, is filled with the specified air pressure, and the tire is placed on a flat plate in a vertical posture, and a load corresponding to the specified mass is applied. The side edge of the contact surface to the flat plate of the tire when it is worn.

In this case, “applicable rim” refers to the rim specified in the following standards according to the tire size, and “specified air pressure” refers to the air pressure specified in accordance with the maximum load capacity in the following standards. The maximum load capacity refers to the maximum mass allowed to be loaded on the tire according to the following standards. The “specified mass” refers to the above maximum load capacity.
The air here can be replaced with an inert gas such as nitrogen gas or the like.

  The standard is determined by an industrial standard that is valid for the region where the tire is produced or used. For example, the “THE TIRE AND RIM ASSOCIATION INC. YEAR BOOK” in the United States, and “THE” in Europe. “STANDARDS MANUAL” of European Tire and Rim Technical Organization, and “JATMA YEAR BOOK” of Japan Automobile Tire Association in Japan.

Further, the “trend” lateral groove extending in the tread width direction means a groove having a long extension length in the tread width direction as compared with the extension length in the tread circumferential direction.
Therefore, when the extension length in the tread circumferential direction is zero, it is naturally included in the lateral groove.

  On the other hand, the inclined wall provided on the side of the intermediate portion in the extending direction of the inclined groove, and thus the inclined groove itself can be terminated without opening any groove, in this case More preferably, the inclined groove is opened at the ground contact end with the inclined wall portion.

  In the inclined groove structure according to the present invention, an inclined wall portion that gradually becomes wider toward the side portion is provided in the groove wall on one side in the region on the side portion side from the intermediate position in the extending direction of the inclined groove. Thus, drainage water flowing in various directions within the contact area of the tread surface is efficiently collected into the inclined groove based on the substantial widening action of the groove width of the inclined groove by the inclined wall portion. On the other hand, the drainage stream can be drained smoothly and quickly and efficiently outside the tread area, with few restrictions on the direction of flow, and as a result Wet drainage performance can be realized.

  That is, the streamline of the drainage water flow that naturally flows in the contact area of the tread surface is usually indicated by a line segment FL when the contact area is viewed from the road surface side in FIG. 2 is formed on the tread tread surface CF with respect to such a drainage water flow, for example, as illustrated in FIG. When draining the outside of the contact area CT by the inclined groove ICG whose depth and width are almost uniform over the entire length, the inclined groove ICG is formed in the contact area CT according to the extending direction of the tire and the rotation of the tire. 2B, the maximum drainage function is exhibited only when the direction of extension of the drainage streamline FL that continuously changes within the groove is shown in FIG. 2B. In the direction in which the inclined groove ICG extends In the case where an inclined wall portion IW whose width in the developed view gradually increases toward the side portion side, in other words, toward the groove end side is provided on the side portion side from the portion position, the extension of the groove bottom portion of the inclined groove ICG Due to collision, bending, etc. of the drainage water flow for all of the drainage water flow having the streamline FL included in the range of the angle α sandwiched between the direction and the extending direction of the outer edge of the inclined wall portion IW Since the maximum discharge function can be exhibited without loss of drainage energy, the inclined groove of FIG. 2 (b) provided with the inclined wall portion IW is compared with the inclined groove shown in FIG. 2 (a). The drainage efficiency to the outside of the tread contact area CT can be greatly increased.

  On the other hand, since the inclined wall portion of the inclined groove is inclined at an acute angle with respect to the adjacent land surface, the groove width of the inclined groove is substantially increased. Since the decrease in the rigidity of the land portion is effectively suppressed, rather, the rigidity of the land portion adjacent to the inclined wall portion is increased as compared with the case where the inclined wall portion is not formed. Under such high rigidity, it is possible to effectively eliminate the fears of occurrence of large uneven wear and a decrease in steering stability.

In such an inclined groove structure, an inclination in which the width in the development view gradually increases toward the central portion side on the central groove wall on one side from the intermediate position in the extending direction of the inclined groove. By providing the wall, the drainage water stream with streamlines included in the spreading area of the inclined wall part can be smoothly, quickly and efficiently formed into an inclined groove without collision of those water streams, extreme bending, etc. Since it can be collected, the drainage efficiency to the outside of the tread contact area can be further enhanced in combination with the above-described action of the inclined wall portion on the side portion side from the central portion position.

  In this case, it is preferable that the developed contour shape of each inclined wall portion is substantially triangular to increase the strength of the adjacent land portion.

It is to be noted that the inclined wall portion in the side portion side region of the inclined groove and the inclined wall portion in the central portion side region are arranged adjacent to each other in the extending direction of the inclined groove with the apex at the middle position of the inclined groove. In the case of the posture, the narrow portion of the groove is generated at the intermediate position of the inclined groove, and the drainage flow rate can be increased at the intermediate position, so that the drainage efficiency toward the end of the inclined groove is improved. It can be improved further.

By the way, in the present invention, by forming the respective inclined wall portions as described above on the opposite sides across the groove bottom of the inclined groove, between the central portion side region and the side portion side region, A suitable land portion reinforcing function can be exhibited in response to demands for different uneven wear characteristics.
Incidentally contrast, those of the inclined wall portion, be formed on the same side relative to the groove bottom of the inclined groove, under the context of the rotation direction of the tire, it suppresses kickout wear, road crash This is effective in reducing sound.

  Further, when the widening depression angle in the developed view of the inclined wall portion is 1 ° or more and 45 ° or less, more preferably 2 ° or more and 30 ° or less, the inclined wall portion is sufficiently provided with the functions described above. Even if it is made to exhibit, the road surface collision noise of the land part which generate | occur | produces at the time of load rolling of a tire resulting from the fact that the groove width of an inclination groove | channel is substantially expanded by an inclination wall part can be suppressed advantageously.

  Here, when the inclined wall portion provided in the region on the side portion side from the intermediate position in the extending direction of the inclined groove is extended to a position reaching the circumferential groove, the grounding end or the lateral groove, the inclined wall portion is inclined. The drainage efficiency can be further improved by causing the drainage water flow that has passed through the wall portion to be discharged more quickly into any one of the grooves.

On the other hand, when the inclined wall provided in the region on the side of the intermediate position in the extending direction of the inclined groove is terminated without opening any of the grooves, The drainage that has flowed into the inclined groove through the kick-out side contour line of the tread surface area can be quickly discharged to the front side and the side side of the tire under the action of the inclined wall portion.
This is more effective when the inclined wall portion is opened at the ground contact end to make the drainage to the side of the tire smoother.

  FIG. 3 is a development view of a tread pattern showing an embodiment of the present invention. The tread pattern is formed in a straight line at the center of the tread surface and extends in an annular shape, and a central circumferential groove 1. Each of the side circumferential grooves 2 is formed on each side portion that is equally spaced from the groove 1 to the respective grounding end CE side, and also extends linearly and continues in the tread circumferential direction. In addition, each narrow groove 3 formed between the central circumferential groove 1 and each side circumferential groove 2 and linearly continuing in the circumferential direction, and an inclined posture with respect to the tread circumferential direction, Each of the inclined grooves 4 extends from the center portion to the side portion and has the extending directions opposite to each other across the central circumferential groove 1.

  Here, each inclined groove 4 that contributes to the formation of a directional pattern that specifies the rotational direction of the tire is curved from the center position somewhat spaced from the central circumferential groove 1, and in a curved shape that protrudes upward in the figure The side circumferential groove 2 and the tread grounding end CE are provided so as to extend to a position in the vicinity of the tread end. With respect to the position where the inclined groove 4 intersects the narrow groove 3, the side circumferential groove 2 On the side, the groove wall on one side of the inclined groove 4, in the figure, on the groove wall on the lower side, is inclined at an acute angle with respect to the surface of the adjacent land portion 5 as will be described later, and the developed view of the tread pattern An inclined wall portion 6 that gradually increases in width toward the side of the tread surface is provided, and the inclined wall portion 6 is extended to a position that intersects the side circumferential groove 2, and the contour thereof The shape is a substantially triangular shape with two sides forming a curved shape in the figure.

  On the other hand, in the extended portion of the inclined groove 4 closer to the center than the narrow groove 3, it is on either side, in the figure, on the groove wall on the upper side, with respect to the surface of the land portion 7 adjacent thereto. Also, as will be described later, there is provided an inclined wall portion 8 which is inclined at an acute angle and gradually increases the width of the illustrated unfolded view toward the central portion side of the tread surface, and this inclined wall portion 8 is formed in the central circumferential groove 1. The process is terminated without intersecting, and the outline shape thereof is made substantially triangular as described above.

Here, each inclination wall part 6 and 8 can be made into the inclination aspect as shown in an expanded sectional view in FIG. 4 with respect to each surface of the adjacent land part 5 and 7, and in the case of illustration, it is inclined. The inclination angles β ₁ , β ₂ , γ ₁ and γ ₂ with respect to the adjacent land surface of the walls 6 and 8 are all set to the same angle.

  Here, the width of each of the inclined wall portions 6 and 8 is defined as a width measured in a normal direction orthogonal to the groove bottom center line of the inclined groove 4. The maximum width is inherently generated at the opening position to the side circumferential groove 2 in the groove bottom portion of the inclined groove 4 as shown by the phantom line in the enlarged view of the main part in FIG. Since the formation of the inclined wall portion 6 in the side circumferential groove 2 is meaningless, the inclined wall portion 6 is terminated at a position where it reaches the circumferential groove 2.

In addition, as for the inclined wall portion 8, the maximum width of the inclined wall portion 8 is originally generated at the inner end of the groove bottom portion on the tread tread surface side as shown by the phantom line in FIG. In order to prevent the inclined wall portion 8 from crossing the central circumferential groove 1, the width of the inclined wall portion 8 is gradually reduced from the vicinity of the inner end to the inner end position.
Therefore, in this case, the inclined wall portion that satisfies the requirements in the present invention is formed between the position where the development width is minimum and the position where the development width is minimum. It becomes the wall portion 9. Therefore, in this embodiment, a predetermined inclined wall portion is provided only in a part of the inclined groove 4 in the region closer to the center than the intermediate position in the extending direction.

And further, in each such inclined walls 6 and 8, preferably less 45 ° 1 ° or more widened included angle of definitive deployment view, more preferably, to 30 ° inclusive 2 °. Here, when the apex of the inclined wall portion is an intersection of straight lines, this widening angle is defined by the straight line extending along the groove bottom edge of the inclined groove and the adjacent land of the inclined wall portion when the tread pattern is developed. Is defined as an angle between the straight line and the boundary line with the part surface, but when the apex of the inclined wall part is the intersection of the curves as shown in the figure, as shown in FIG. Straight lines 13 and 14 connecting the apex position and the maximum width position of the inclined wall portions 6 and 8 existing on the normal lines 11 and 12 with respect to the groove bottom center line 10 and the normal lines 11 and 12 are inclined walls. The above-mentioned widening angle is defined by the included angles A and B ° between the straight lines 15 and 16 that connect the positions of the portions 6 and 8 that intersect the groove bottom side edge and the vertex positions of the inclined wall portions 6 and 8.

According to the embodiment as described above, the inclined groove 4 is configured so that the lowering of the rigidity of the land portions 5 and 7 is effectively suppressed under the action of the inclined wall portions 6 and 8 provided on the inclined grooves 4, respectively. Combined with the action of the grooves 1 and 2 and the narrow groove 3, excellent wet drainage performance can be exhibited.

  FIG. 6 is a developed view of a tread pattern showing another embodiment. This is a central circumferential groove 21 slightly to the left of the tread tread surface from the center position of the tread, and each side on each tread side. The part circumferential grooves 22 are both linearly extended to form an annular shape, and in the figure, in the right half of the tread surface, from the center side thereof, through the side circumferential grooves 22 and the tread grounding end CE, the tread A plurality of inclined grooves 23 extending in the upper right direction are formed at a predetermined pitch in a curved form that protrudes upward to a position near the end, and in the left half of the tread surface, the central circumferential groove 21 is opened. In addition, the side circumferential groove 22 is provided with a plurality of short inclined grooves 24 that do not open and end in a curved form that protrudes downward in the drawing, and the side circumferential groove 22. Of the width direction groove 26 opened in both the tread end circumferential groove 25 and Several are formed in a form that protrudes downward, and each of the inclined grooves 23 has an extension portion between the central circumferential groove 21 and the side circumferential groove 22 that is similar to that described above. Inclined wall portions 27 and 28 are provided.

  In this embodiment, in which the basic groove arrangement of the tread pattern is different from the previous embodiment, each inclined groove 23 itself is curved and extended as in the previous case. An inclined wall portion 27 that is formed on the side of the intermediate portion and intersects the side circumferential groove 22 and an inclined wall portion 28 that is formed on the intermediate portion of the intermediate portion and adjacent to each other. In the point which makes the boundary line with the surface of the land parts 29 and 30 the straight line, and the point which makes the ring part line by the side of the central circumferential groove of the central part side inclined wall part 28 the straight line parallel to the circumferential groove 21 The configuration is somewhat different from the inclined wall portions 6 and 8 described above.

  In addition, the inclined groove 23 of this embodiment can also achieve excellent wet drainage performance while effectively suppressing a decrease in rigidity of the land portions 29 and 30 in the presence of the respective inclined wall portions 27 and 28. it can.

  FIG. 7 is a developed view showing still another embodiment of the right half portion of the tread pattern. This is shown in the side circumferential groove 32 formed at a distance from the central circumferential groove 31 to the periphery thereof. One straight inclined groove 34 that extends to the right is formed in each horizontal groove 33 that is open at one end of the horizontal groove 33 that extends to the upper right between the grooves and that has the other end terminated in the land portion. When the upper end of the groove is opened, the groove walls on the opposite sides of the inclined groove 34 whose lower end ends in the land portion are opposite to each other in the side portion side region and the central portion side region from the intermediate position in the extending direction. In the figure, the side-side inclined wall portion 35 formed on the right groove wall is extended under a gradual widening to a position where it intersects the lateral groove 33. The central inclined wall 36 formed on the left groove wall is It is to a position where its lower edge is horizontal, and is formed by extending in gradually widening under.

  In addition, in the place shown in this figure, each inclined wall part is formed in the groove wall on the opposite side to that described above, the side-side inclined wall part is on the left side of the groove bottom, and the central-side inclined wall It is also possible to arrange the portion on the right side of the groove bottom. In this case, when the side-side inclined wall portion is extended to a position intersecting with the lateral groove 33, the side-side inclined wall portion is In the same manner as described in FIG. 4, the process is terminated in the middle of the extension of the groove bottom.

  By the way, although not shown, the side-side inclined wall portion can be made independent of the groove bottom, or can be extended to the tread grounding end CE together with the groove bottom. Regardless of whether or not it intersects the circumferential groove, the lateral groove, etc., the required function as described above can be sufficiently exerted on the side-side inclined wall portion.

In the present invention , an inclined wall portion is provided on each of the side portion side and the central portion side with respect to the intermediate portion position in the extending direction of one inclined groove . where indicated, it is Oite a focus on smoothness etc. drainage from the tread ground contact area, only the inclined wall portion side portion than the middle portion located in the extending direction thereof.

FIG. 8 is a view showing a reference example in the case where only such a side-side inclined wall portion 42 is provided on one wall portion of the inclined groove 41. In this figure , the drawing is hatched . In the wall portion 43 shown, the inclination angle with respect to the surface of the adjacent land portion 44 is the same regardless of the width of the wall portion, as shown in each of the ii cross section and the ii-ii cross section. .
By the way, the same cross-sectional shape of the remaining part of the inclined wall part 42 as the extension part of the wall part 43 can be made into a form shown as a iii-iii cross section in a figure.
Even in this case, the widening angle C of the inclined wall portion 42 can be set to 1 ° to 45 °.

FIG. 9 is a developed view of a tread pattern showing still another embodiment of the present invention, in which the tire equatorial line X is separated from each other in the opposite direction, and in the figure, extends in an “inverted eight-letter shape”. , For each inclined groove 51 having a straight groove bottom portion that ends in the land without intersecting each other or opening to the ground contact CE, the intermediate portion in the extending direction of the inclined groove 51 In the region on the side portion side from the position, a predetermined inclined wall portion 52 is formed on the groove wall on the ground contact CE side, and in the region on the center portion side from the intermediate position in the extending direction, the groove wall on the equator line X side is formed. are those respectively provided with predetermined inclined wall portion 53, the respective inclined wall portions 52 of the side portion, which was then opened to the tread ground contact edge CE with an extension from a wall portion which meets the requirements referred to in the invention of this is there.

  In such a tread pattern, the water in the tread contact area CT taken into the inclined groove 51 by the load rolling of the tire mainly passes through the kicking side outline OL of the contact area CT. The tire is discharged to the front and side of the tire.

Further, in the illustrated tread pattern, since the side inclined wall portion 52 is open to the tread grounding end CE, the inclined groove 51 causes the water taken therein to the side of the tire through the grounding end CE. Can also be discharged. By the way, in the place shown in this figure, by changing the contour shape of the inclined wall portion 52 or the like, it is possible to make the whole wall portion satisfying the requirements referred to in the present invention. When it is opened, the drainage efficiency to the side of the tire can be further increased.
Although not shown, the inclined wall portion 52 can be terminated in the tread surface without being opened at the tread ground contact CE regardless of the form of the inclined wall portion 52.

Further, as shown in FIG. 10 (a), the groove walls forming the respective inclined wall portions 52 and 53 of the inclined groove 51 can be reversed from those shown in FIG. An inclined wall portion 52 on the side of the intermediate portion in the direction is formed on the groove wall on the equator line X side, and an inclined wall portion 53 on the central portion side of the intermediate portion is formed on the groove wall on the grounding end CE side. Will be.
Incidentally, that Mashimasu extending bends the groove bottom portion of the inclined groove, in the reference example shown in FIG. 10 (b) and (c), the respective inclined wall portions 52 and 53 together to form the same grooves wall Yes .

Example tire 1 having a tread pattern shown in FIG. 3, Example tire 2 having a tread pattern shown in FIG. 6, and a tread shown in FIG. When the straight wet drainage performance and uneven wear resistance performance of Example tire 3 having a pattern were compared with those of a conventional tire having a tread pattern shown in FIG. 11, the results shown in Table 1 were obtained.
In Table 1, the dimensions of each tire are also shown.

The straight wet drainage performance and uneven wear resistance performance shown in the table are as follows: a tire with a filling air pressure of 220 kPa is mounted on a real vehicle, the vehicle is subjected to a load condition equivalent to two passengers, and a wet road surface with a water depth of 5 mm. By measuring the speed of the hydroplaning phenomenon when passing the road, and visually evaluating the tread tread after running 5000km and measuring the remaining groove by mode driving assuming highways, urban roads and mountain slopes, respectively. The index was evaluated using the conventional tire as a control.
Here, the larger the index value, the better the result.

  As shown in Table 1, it is clear that all of the example tires can exhibit excellent straight wet drainage performance and uneven wear resistance performance.

It is a bottom view which shows the drainage flow line in a tread contact area. It is explanatory drawing which shows the effect | action of an inclination groove | channel. It is an expanded view of the tread pattern which shows embodiment of this invention. It is an enlarged view which illustrates the formation aspect of an inclined wall part. It is an enlarged view which illustrates how to obtain the widening angle. It is an expanded view which shows other embodiment. It is an expanded view which shows other embodiment about a half part. It is a figure which shows the reference example of an inclined wall part. It is an expanded view which shows other embodiment. It is a figure which illustrates the other formation aspect of an inclination wall part , and another reference example . It is an expanded view which shows the tread pattern of the conventional tire.

Explanation of symbols

1, 21, 31 Central circumferential groove 2, 22, 32 Side circumferential groove 3 Narrow groove 4, 23, 34, 41, 51 Inclined groove 5, 7, 29, 30, 44 Adjacent land portion 6, 27, 35, 42 , 52 Side-side inclined wall portions 8, 28, 36, 53 Center-side inclined wall portions 9, 43 Wall portion 10 Groove bottom center line 11, 12 Normal line 13, 14, 15, 16 Straight line 24 Short inclined groove 25 Tread End circumferential groove 26 Width direction groove 33 Horizontal groove CE Grounding end A, B, C Widening sandwich angle β ₁ , β ₂ , γ ₁ , γ ₂ Inclination angle T Tire CF Tread tread surface CT Contact area FL Stream line OL Step side contour ICG Inclined groove IW Inclined wall part α Angle

Claims (7)

An inclined groove that is inclined with respect to the circumferential direction of the tread and extends from the center of the tread surface to the side to contribute to the formation of the tread pattern,
An inclined wall portion that is inclined at an acute angle with respect to the surface of the adjacent land portion is provided on either side of the groove wall in the region on the side side from the intermediate position in the extending direction of the inclined groove, and this inclination Increasing the width of the wall portion in the development view of the tread pattern gradually toward the side portion side ,
A part or all of the region on the central side from the intermediate position in the extending direction of the inclined groove is inclined at an acute angle with respect to the adjacent land surface on the central groove wall on one side of the inclined groove. While providing an inclined wall portion, the width of the inclined wall portion in the development view of the tread pattern is gradually increased toward the central portion side,
An inclined groove structure of a tire tread in which respective inclined wall portions are formed on opposite sides of each other with a groove bottom of the inclined groove interposed therebetween . The inclined groove structure of a tire tread according to claim 1, wherein a contour shape of the inclined wall portion in a developed view of the tread pattern is substantially triangular. The inclined groove structure of a tire tread according to claim 1 or 2, wherein an inclination angle of an inclined wall portion with respect to an adjacent land surface is reduced as the width of the developed view increases. The inclined groove structure of a tire tread according to any one of claims 1 to 3, wherein a widening depression angle of the inclined wall portion in the unfolded view is 45 ° or less. An inclined wall portion provided in a region on the side of the intermediate position in the extending direction of the inclined groove is formed on the tread tread surface and is continuously provided in the circumferential groove or grounding end in the circumferential direction, or in the tread width direction. The inclined groove structure for a tire tread according to any one of claims 1 to 4, wherein the inclined groove structure is extended to a position reaching a lateral groove extending to the tire tread. The tire tread according to any one of claims 1 to 4, wherein the inclined wall portion provided in the region on the side portion side from the intermediate position in the extending direction of the inclined groove is terminated without opening any groove. Inclined groove structure. The inclined groove structure for a tire tread according to claim 6, wherein the inclined groove is opened at the ground contact end by an inclined wall portion provided in a region on the side portion side from the intermediate portion position.

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