JP4122179B2 - Pneumatic tire - Google Patents

Description

【００４１】
テストの結果、実施例のものは、ウエット性能、操縦安定性能、耐偏摩耗性能をバランス良く向上していることが確認できた。
【００４２】
【発明の効果】
以上説明したように、本発明の空気入りタイヤは、偏摩耗や乾燥路面での操縦安定性を損ねることなく耐ハイドロプレニング性能を向上しうる。
【図面の簡単な説明】
【図１】本発明の一実施形態を示すトレッド部の展開図である。
【図２】その右半分を拡大して示す右半分拡大図である。
【図３】図１の左半分を拡大して示す右半分拡大図である。
【図４】本発明の他の実施形態を示すトレッド部の展開図である。
【図５】従来のトレッド部の展開図である。
【符号の説明】
２ トレッド面
３ａ 中央の縦溝
３ｂ 外の縦溝
４ａ 中央陸部
４ｂ 中間陸部
４ｃ 外の陸部
５ 傾斜溝
５ｉ 傾斜溝の内端
５ｏ 傾斜溝の外端
５Ｐ 傾斜溝の中間部
６ 補助溝
６ｉ 補助溝の内端
６ｉ 補助溝の外端[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire capable of improving wet performance.
[0002]
[Prior art and problems to be solved by the invention]
In a pneumatic tire, particularly a pneumatic radial tire for passenger cars, a relatively small angle with respect to the tire circumferential direction is shown in FIG. 5 in order to break the water film on the road surface and enhance its removal effect. For example, an inclined groove a inclined at about 10 to 45 ° is provided. Further, the inclined groove a is, for example, arranged symmetrically with respect to an arbitrary point on the tire equator C, and is formed as a non-directional pattern so that the mounting direction on the vehicle is not limited.
[0003]
In such a pneumatic tire, when the rotation direction R shown in the figure is taken, the inclined groove a1 arranged on the right side of the tire equator C in FIG. 5 starts to contact from the inner end b on the tire equator side. The water film in the center can be effectively discharged outward in the tire axial direction. However, in the inclined groove a2 provided on the left side of the tire equator C, since the ground contact is started from the outer end c in the tire axial direction, it is easy to guide the water film on the road surface to the tread central portion side contrary to the above. As described above, when an inclined groove having a relatively steep inclination is used for the non-directional pattern, it is not possible to sufficiently expect the drainage efficiency to be improved on one side of the tire equator.
[0004]
The present invention has been devised in view of the above problems, and is provided with an inclined groove extending at an angle θ of 10 to 45 degrees with respect to the tire circumferential direction without inversion of the direction. In addition, the drainage performance is further improved, particularly in the non-directional pattern, by providing an auxiliary groove that communicates with the middle portion of the inclined groove and extends outwardly in the tire axial direction in a direction opposite to the inclined groove. The object is to provide a pneumatic tire.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is characterized in that a central longitudinal groove comprising one on the tread surface extending on the tire equator or two extending on both sides of the tire equator in the tire circumferential direction, and the central longitudinal groove. By providing an outer vertical groove extending in the tire circumferential direction on both sides, a pneumatic tire that partitions an intermediate land portion between the central vertical groove and the outer vertical groove,
The intermediate land portion is inclined at an angle θ of 10 to 45 degrees with respect to the tire circumferential direction and without reversing the direction from an inner end separating a small distance A in the tire axial direction from the central longitudinal groove. Extending the outside in the tire axial direction and separating the inclined groove communicating with the outer vertical groove,
The inclined groove is inclined in the opposite direction of the tire circumferential direction at an angle of 20 to 70 degrees with respect to the tire circumferential direction from an intermediate portion excluding both end portions of the inclined groove, and extends outward in the tire axial direction and further to the outer vertical direction. An auxiliary groove communicating with the groove or another inclined groove adjacent in the tire circumferential direction is provided.
[0006]
In the invention according to claim 2, the groove width Wi of the central longitudinal groove is larger than 1.0 times and 2.5 times or less of the groove width Wo of the outer longitudinal groove. The pneumatic tire according to claim 1.
[0007]
According to a third aspect of the present invention, the auxiliary groove has a distance Lp that is 0.3 to 0.7 times the width Lm in the tire axial direction of the intermediate land portion from the groove edge of the outer vertical groove in the tire axial direction. The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire communicates with the inclined groove at a position separated inward.
[0008]
The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the small distance A is 10 to 40% of a groove width of the central longitudinal groove. is there.
[0009]
According to a fifth aspect of the present invention, the intermediate land portion has a first corner portion where the groove wall on the outer side in the tire axial direction of the inclined groove intersects with the groove wall on the outer side in the tire axial direction of the auxiliary groove. The second corner portion where the groove wall on the outer side in the tire axial direction of the inclined groove and the groove wall on the inner side in the tire axial direction of the auxiliary groove intersect with each other is a sharp non-chamfered portion. The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings, taking a pneumatic radial tire for passenger cars as an example. FIG. 1 is a development view of a tread surface in which a tread surface 2 of a pneumatic tire (not shown) of the present embodiment is developed, FIG. 2 is an enlarged view of the right half of the right half, and FIG. The left half enlarged view which expands and shows is shown, respectively.
[0011]
In the figure, the tread surface 2 includes two central longitudinal grooves 3a and 3a extending on both sides of the tire equator C in the tire circumferential direction, and an outer vertical extending on both sides of the central longitudinal groove 3a in the tire circumferential direction. Grooves 3b and 3b are provided. The central longitudinal grooves 3a and 3a and the outer longitudinal grooves 3b and 3b are illustrated as being substantially symmetrical with respect to the tire equator C, respectively. It should be noted that the central longitudinal groove 3a can be constituted by one extending over the tire equator C instead of providing two. Further, in this embodiment, when a change in pitch such as a pitch variation is ignored, the left and right tread surfaces defined by the tire equator C are substantially point-symmetric with respect to a point on the tire equator, so-called non-directionality. The thing formed with the tread pattern is illustrated. Since such a tire can be used without specifying the direction (in other words, the rotational direction) when mounted on the vehicle, it is useful for facilitating the mounting.
[0012]
In the present example, the central longitudinal groove 3a and the outer longitudinal groove 3b are both linearly extending continuously in the tire circumferential direction. The groove widths Wi and Wo of the central vertical groove 3a and the outer vertical groove 3b (the groove width is the opening width at the tread surface 2 and the same shall apply hereinafter) are not particularly limited, but considering drainage For example, it is desirable to set the tread ground contact width TW to about 2 to 7%, more preferably about 2 to 5%. In the present embodiment, the groove width Wi of the central vertical groove 3a is formed larger than the groove width Wo of the outer vertical groove. Thereby, the drainage effect in the vicinity of the tire equator C having poor drainage can be further enhanced.
[0013]
Particularly preferably, the groove width Wi of the central longitudinal groove 3a is larger than 1.0 times and 2.5 times or less, more preferably 1.5 to 2.0 times the groove width Wo of the outer longitudinal groove 3b. In this case, it is particularly preferable that the groove width Wi of the central longitudinal groove 3a is 5.0 to 8.0 mm. Thereby, it is effective in preventing the fall of the feeling of rigidity at the time of turning, improving the drainage property of the center part of a tread.
[0014]
The tread ground contact width TW is a distance in the tire axial direction between the tread ground contact ends E and E when the tire is assembled on a regular rim and filled with a regular internal pressure and a regular load is applied to the plane. To do. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO If so, use "Measuring Rim".
[0015]
In addition, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. It is the maximum air pressure for JATMA and the table “TIRE LOAD LIMITS” for TRA. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO, but 180 kPa for tires for passenger cars. Furthermore, “regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is specified for JATMA, and the table “TIRE LOAD LIMITS” for TRA. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” if it is ETRTO, but if the tire is for a passenger car, it is 0.88 times the value.
[0016]
In addition, if the groove depth of each of the vertical grooves 3a and 3b is too small, it is difficult to secure a sufficient amount of drainage and the drainage performance is likely to be lowered. Conversely, if too large, the rigidity of the land portion is liable to be lowered and steering stability is easily impaired. . From such a viewpoint, the depth of the central vertical groove 3a and the outer vertical groove 3b is not particularly limited, but is, for example, 6.0 to 10.0 mm, and more preferably 7.0 to 9.0 mm. It is desirable to set the degree.
[0017]
Further, in the pneumatic tire of the present embodiment, by providing the central vertical groove 3a and the outer vertical groove 3b, a central land portion 4a formed between the central vertical grooves 3a and 3a on the tread surface 2, and An intermediate land portion 4b formed between the central vertical groove 3a and the outer vertical groove 3b, and an outer land portion 4c formed between the outer vertical groove 3b and the tread grounding end E are partitioned. is doing.
[0018]
In this example, the central land portion 4a is formed by ribs that are substantially continuous in the tire circumferential direction. This increases the rigidity of the central land portion 4a where the contact pressure becomes high, and helps to improve the steering stability and the stability when going straight. Further, the rib can be provided with a siping S substantially not involved in drainage, a lug-shaped cut (not shown) in the tire axial direction, and the like. If the width Lc in the tire axial direction of the central land portion 4a is too large, the drainage near the tire equator tends to deteriorate. Conversely, if the width is too small, the rigidity of the central land portion 4a is remarkably lowered and the steering stability is reduced. Deterioration, rubber chipping, and uneven wear are likely to occur. From such a viewpoint, it is desirable that the width Lc of the central land portion 4a is, for example, about 10 to 25%, more preferably about 15 to 20% of the tread ground contact width TW.
[0019]
Further, the intermediate land portions 4b and 4b are provided with inclined grooves 5 extending in the tire circumferential direction at an angle θ of 10 to 45 degrees with respect to the tire circumferential direction and extending without inversion. In this example, since the non-directional pattern is used as described above, the inclined groove 5 disposed on the right side of the tire equator C in FIG. The inclined groove 5 formed on the left side is exemplified by one that extends downward to the left in the tire axial direction.
[0020]
The inclined groove 5 has an inner end 5i separating a small distance A in the tire axial direction from the central vertical groove 3a, and communicates with the outer vertical groove 3b extending outward from the inner end 5i in the tire axial direction. is doing. In this way, the inclined groove 5 that inclines at a relatively small angle with respect to the tire circumferential direction has a water film that exists between the tread surface 2 and the road surface in order with the rotation of the tire in the outer direction in the tire axial direction. Alternatively, it can be efficiently guided to the inside and discharged.
[0021]
Specifically, the inclined groove 5 provided on the right side of the tire equator C shown in FIG. 2 sequentially contacts the road surface from the inner end 5i side to the outer end 5o side with the rotation R of the tire. As a result, the inclined groove 5 can effectively guide and discharge the water film on the tire equator C side to the outer vertical groove 3b (outer in the tire axial direction) as indicated by an arrow F1. Here, if the angle θ of the inclined groove 5 is larger than 45 degrees, a large resistance force is likely to act on the flow of such drainage, which is not preferable. On the contrary, if it is less than 10 degrees, the rigidity of the intermediate land portion 4b is likely to be lowered, and the steering stability may be deteriorated.
[0022]
In addition, the inclined groove 5 provided on the left side of the tire equator C shown in FIG. 3 sequentially contacts the road surface from the outer end 5o side to the inner end 5i side in the tire axial direction as the tire rotates. As a result, as shown by the arrow F3 in the inclined groove 5, the water film on the shoulder side can be guided to the central vertical groove 3a and discharged. The inner end 5i of the inclined groove 5 is not in communication with the central vertical groove 3a, but the central vertical groove 3a is substantially utilized by setting a small distance A between the inner end 5i and the central vertical groove 3a. Can drain a lot of wastewater. Here, it is conceivable to connect the inner end 5i of the inclined groove 5 to the central vertical groove 3a. In such an embodiment, the intermediate land portion 4b is connected to the inner end 5i of the inclined groove 5 and the central vertical groove 3a. An acute land portion with small rigidity sandwiched between the two is formed, and the rigidity of the intermediate land portion 4b is lowered, which leads to deterioration of steering stability. Conversely, even if the small distance A is too large, the water film discharge effect at the center of the tread tends to decrease. From such a viewpoint, the small distance A is preferably 10 to 40%, more preferably 15 to 30% of the groove width Wi of the central longitudinal groove 3a.
[0023]
The inclined groove 5 of this example illustrates an aspect in which the angle θ gradually increases from the inner side in the tire axial direction toward the outer side in the tire axial direction. As a result, the angle θ can be reduced on the inner end 5i side of the inclined groove 5, the initial resistance when the water film near the tire equator flows into the inclined groove 5 is reduced, and water is efficiently allowed to flow into the inclined groove 5. In addition, by increasing the angle of the inclined groove 5 smoothly, it helps to guide the drainage to the outer vertical groove 3b without abrupt resistance. In this case, the angle θ satisfies the angle of 10 to 45 degrees, more preferably 15 to 45 degrees at any position of the inclined groove 5, and the angle θ is enlarged and shown in FIG. Further, it is measured at the intermediate line 5C of the groove width of the inclined groove 5, and when the angle θ changes, it can be specified by the inclination of the tangent to the intermediate line 5C.
[0024]
In order to improve the drainage while ensuring the rigidity of the intermediate land portion 4b, such an inclined groove 5 has a circumferential pitch Ni in the tire circumferential direction as shown in FIG. It is desirable that the thickness M is 0.6 to 0.8 times, more preferably 0.65 to 0.75 times.
[0025]
Further, the groove width or depth of the inclined groove 5 is not particularly limited. However, if both are too small, sufficient drainage capacity cannot be obtained, and conversely if too large, the rigidity of the intermediate land portion 4b is lowered and maneuvered. There is a tendency to impair stability. From such a viewpoint, the groove width of the inclined groove 5 is, for example, 2 mm or more, more preferably 4 mm or more, further preferably about 4 to 7 mm, and the groove depth is 3 mm or more, more preferably 5 mm or more. And more preferably 6 to 8 mm. When the groove width changes, it is desirable that the average groove width is included in the above range. In particular, the groove width of the inclined groove 5 is gradually increased from the inner end 5i toward the outer end 5o as in this example. Is effective.
[0026]
Moreover, in this invention, the auxiliary groove 6 is provided in the said intermediate land part 5b. The auxiliary groove 6 inclines in a direction opposite to the inclined groove 5 from an intermediate portion 5P (shown in FIG. 2) excluding both end portions (that is, the inner end 5i and the outer end 5o) of the inclined groove 5 and tires. It extends outward in the axial direction and communicates with the outer vertical groove 3b or another inclined groove 5 adjacent in the tire circumferential direction. Incidentally auxiliary groove 6 shows the one provided one by one to each of the inclined grooves 5.
[0027]
In the right intermediate land portion 4b shown in FIG. 2, such auxiliary grooves 6 are in contact with the road surface sequentially from the outer end 6o side to the inner end 6i side in the tire axial direction as the tire rotates. Thereby, as shown by the arrow F2, the water film near the outer vertical groove 3b can be guided to the middle portion of the inclined groove 5 and discharged from the outer vertical groove 3b. In addition, in the left intermediate land portion 4b shown in FIG. 3, the auxiliary groove 6 sequentially contacts the road surface from the inner end 6i side to the outer end 6o side in the tire axial direction with the rotation R of the tire. Thereby, as shown by the arrow F4, the water film on the tire equator side can be guided to the outer vertical groove 3b and discharged. At this time, part of the drainage flowing through the inclined groove 5 in the direction of the arrow F3 can flow into the auxiliary groove 6 and be guided to the outer vertical groove 3b. Accordingly, in the non-directional pattern, the drainage flow toward the tire axial direction outside can be formed in the intermediate land portions 4b on both sides, and the drainage performance at the center portion of the tread can be prevented and the drainage performance can be further improved. .
[0028]
The outer end 6o of the auxiliary groove 6 may communicate with the outer vertical groove 3b, or may communicate with another inclined groove 5 adjacent in the tire circumferential direction. In the latter case, it is preferable to communicate with the vicinity of the outer end 5o of the inclined groove 5 as much as possible. Furthermore, the outer end 6o of the auxiliary groove 6 can be connected to a communication portion where the outer vertical groove 3b and the other inclined groove communicate with each other, and this aspect is exemplified in this example.
[0029]
The groove width or depth of the auxiliary groove 6 is not particularly limited, but if both are too small, sufficient drainage capacity cannot be obtained, and conversely if too large, the rigidity of the intermediate land portion 4b is lowered and steering stability is improved. There is a tendency to damage. From such a viewpoint, the groove width of the auxiliary groove 6 is, for example, 2 mm or more, more preferably 4 mm or more, further preferably about 4 to 7 mm, and the groove depth is, for example, 2 mm or more, more preferably 3 mm. As described above, it is more preferable that the thickness is about 4 to 6 mm. When the groove width changes, it is desirable that the average groove width is included in the above range, and it is particularly effective to gradually increase the groove width of the inclined groove 5 from the inner end 5i toward the outer end 5o. is there.
[0030]
Moreover, in order to achieve the above-mentioned action more effectively, the angle δ (shown in FIG. 2) of the auxiliary groove 6 with respect to the tire circumferential direction is, for example, 20 to 70 degrees, more preferably 40 to 60 degrees. desirable. When the angle δ is less than 20 degrees, a sharp land portion is formed between the inclined groove 5 and the land portion rigidity of the intermediate land portion 4b is likely to be uneven and reduced. The drainage performance tends to be reduced. The angle δ may be constant, or may be configured to gradually decrease or gradually increase (in this example, gradually increase) toward the outer side in the tire axial direction.
[0031]
Further, the intermediate portion 5P of the inclined groove 5 to which the auxiliary groove 6 communicates (determined as an intersection of the intermediate edges of each groove) is not particularly limited, but preferably, as shown in FIG. 2, the tire of the outer vertical groove 3b. It is desirable to provide a distance Lp that is 0.3 to 0.7 times the width Lm of the intermediate land portion 4b in the tire axial direction from the groove edge 3be on the axially inner side at a position separated inward in the tire axial direction. When the distance Lp is less than 0.3 times the width Lm of the intermediate land portion 4b, the length of the auxiliary groove 6 is reduced, and the drainage capacity is likely to decrease. Conversely, when the distance Lp exceeds 0.7 times, the drainage capacity is Although it can be improved, the length of the auxiliary groove 6 becomes large. As a result, the rigidity of the intermediate land portion 4b tends to be lowered, and there is a tendency to cause uneven wear and to deteriorate the steering stability. Particularly preferably, the distance Lp is 40 to 60% of the width Lm of the intermediate land portion 4b. Here, if the width Lm of the intermediate land portion 4b is too small, the steering stability tends to deteriorate, and if it is too large, the balance with the other land portions is impaired and it is easy to cause uneven wear. From such a viewpoint, the width Lm of the intermediate land portion 4b is, for example, preferably 20 to 40%, more preferably 25 to 35% of the tread ground contact width TW.
[0032]
Further, as shown in FIG. 2, the intermediate land portion 4 b of the present embodiment includes a first wall where the groove wall 8 on the outer side in the tire axial direction of the inclined groove 5 and the groove wall 7 on the outer side in the tire axial direction of the auxiliary groove 6 intersect. The corner portion 9 is formed as a chamfered portion 10 rounded into an arc shape. With such a chamfered portion 9, the drainage from the auxiliary groove 6 to the inclined groove 5 is merged more smoothly in the portion of FIG. 2, and the drainage from the inclined groove 6 to the auxiliary groove 6 is more smoothly performed in the portion of FIG. be able to. Therefore, the wet performance can be further improved. The curvature radius r of the chamfered portion 10 is preferably about 10 to 30 mm, for example.
[0033]
The second corner portion 12 where the groove wall 8 on the outer side in the tire axial direction of the inclined groove 5 and the groove wall 11 on the inner side in the tire axial direction of the auxiliary groove 6 preferably remain sharp without being chamfered. The non-chamfered portion 13 is desirable. This prevents a part of the flowing water from the inner end 5i to the outer end 5o of the inclined groove 5 from flowing back to the auxiliary groove 6 side in the portion of FIG. 2, and in the portion of FIG. Helps guide drainage into the water.
[0034]
Further, in the present embodiment, the outer land portion 4c is connected to the outer vertical groove 3b at one end and the horizontal groove 14 having the other end opened at the tread grounding end E, and provided between the horizontal grooves 14 and 14 and the tread. A lug-like groove 15 extending from the ground contact end E in the tire axial direction and terminating without communicating with the outer vertical groove 3b is provided. Thereby, in the outer land portion 4c, an effective drainage effect is obtained by using the tread grounding end E and the outer vertical groove 3b. Further, the width Lo of the outer land portion 4c in the tire axial direction is the largest in this example as compared with other land portions, and is set to Lo>Lm> Lc. The width Lo is preferably about 20 to 40% of the tread grounding width TW, for example.
[0035]
As mentioned above, although embodiment of this invention was explained in full detail, this invention can be implemented in a various aspect, without being limited to the said embodiment. For example, a mode in which the longitudinal grooves 3a and 3b are bent in a zigzag or wave shape, a mode in which the inclined grooves 5 and the auxiliary grooves 6 are arranged in a letter C shape with the tire equator C interposed therebetween as shown in FIG. Various embodiments are included, such as a mode in which siping is appropriately attached to the surface 2.
[0036]
【Example】
A radial tire for a passenger car having a tire size of 195 / 65R15 was prototyped with the pattern shown in FIG. 1, and wet performance, steering stability on a dry road surface, and uneven wear resistance were tested and evaluated. For comparison, the same size tire (conventional example) having the pattern shown in FIG. 5 was also tested. The internal structure is also substantially the same. The test method was as follows.
[0037]
<Wet performance>
A vehicle (displacement 2000cm ³ , rim 6J, internal pressure 180kPa) equipped with a test tire while increasing the speed stepwise on a course with a water depth of 5mm and a length of 20m on an asphalt road with a radius of 100m. The vehicle was allowed to enter and the lateral acceleration (lateral G) was measured, and the average lateral G of the front wheels at a speed of 50 to 80 km / h was calculated (lateral hydroplaning test). The results were expressed as an index with the conventional example being 100. The larger the value, the better.
[0038]
<Steering stability>
A test run is performed on the dry asphalt road surface of the tire test course with the above vehicle, and characteristics relating to steering wheel response, rigidity, grip, and the like are displayed as an index with Comparative Example 1 being 100 by sensory evaluation of the driver. A larger index is better.
[0039]
<Uneven wear resistance>
The vehicle traveled on a highway, urban area, and mountain road for a total of 8000 km, and the state of wear on the tread surface was visually observed.
Table 1 shows the test results.
[0040]
[Table 1]

[0041]
As a result of the test, it was confirmed that the examples had improved wet performance, steering stability performance, and uneven wear resistance performance in a well-balanced manner.
[0042]
【The invention's effect】
As described above, the pneumatic tire of the present invention can improve the hydroplaning performance without impairing uneven wear and steering stability on a dry road surface.
[Brief description of the drawings]
FIG. 1 is a development view of a tread portion showing an embodiment of the present invention.
FIG. 2 is an enlarged view of the right half of the right half.
3 is an enlarged right half view of the left half of FIG. 1; FIG.
FIG. 4 is a development view of a tread portion showing another embodiment of the present invention.
FIG. 5 is a development view of a conventional tread portion.
[Explanation of symbols]
2 tread surface 3a central vertical groove 3b outer vertical groove 4a central land portion 4b intermediate land portion 4c outer land portion 5 inclined groove 5i inclined groove inner end 5o inclined groove outer end 5P inclined groove intermediate portion 6 auxiliary groove 6i Inner end of auxiliary groove 6i Outer end of auxiliary groove

Claims (5)

On the tread surface, there is one central longitudinal groove extending on the tire equator or two extending on both sides of the tire equator in the tire circumferential direction, and an outer longitudinal groove extending on both sides of the central longitudinal groove in the tire circumferential direction. A pneumatic tire that defines an intermediate land portion between the central vertical groove and the outer vertical groove,
The intermediate land portion is inclined at an angle θ of 10 to 45 degrees with respect to the tire circumferential direction and without reversing the direction from an inner end separating a small distance A in the tire axial direction from the central longitudinal groove. Extending the outside in the tire axial direction and separating the inclined groove communicating with the outer vertical groove,
The inclined groove is inclined in the opposite direction of the tire circumferential direction at an angle of 20 to 70 degrees with respect to the tire circumferential direction from an intermediate portion excluding both end portions of the inclined groove, and extends outward in the tire axial direction and further to the outer vertical direction. A pneumatic tire comprising an auxiliary groove communicating with a groove or another inclined groove adjacent in the tire circumferential direction.   The pneumatic tire according to claim 1, wherein the central vertical groove has a groove width Wi that is larger than 1.0 times and 2.5 times or smaller than a groove width Wo of the outer vertical groove. .   The auxiliary groove is formed in the inclined groove at a position separating a distance Lp 0.3 to 0.7 times the width Lm of the intermediate land portion in the tire axial direction from the groove edge of the outer vertical groove. The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire communicates.   The pneumatic tire according to any one of claims 1 to 3, wherein the small distance A is 10 to 40% of a groove width of the central vertical groove.   The intermediate land portion is a chamfered portion formed by rounding a first corner portion where the groove wall on the outer side in the tire axial direction of the inclined groove intersects with the groove wall on the outer side in the tire axial direction of the auxiliary groove in an arc shape, The second corner portion where the groove wall on the outer side in the tire axial direction of the inclined groove intersects with the groove wall on the inner side in the tire axial direction of the auxiliary groove is a sharp non-chamfered portion. 4. The pneumatic tire according to any one of 4 above.

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