JP5320428B2 - Pneumatic tire - Google Patents

Abstract

A pneumatic tire in the invention inhibits deterioration of noise performance and improves mud land performance. A pneumatic tire (1) is provided with a tire shoulder longitudinal furrow (3) and a tire shoulder horizontal furrow (8). The tire shoulder longitudinal furrow (3) is formed to be trapezoidal wave-shaped sawteeth. In the tire shoulder horizontal furrow (8),the angle of a straight line connecting an intersection point (P1) of a furrow central line (8G) and the tire shoulder longitudinal furrow (3), and an intersection point (P2) of a furrow central line (8G) and a grounding terminal (Te) relative to the tire axial direction is 5-20 degrees. The width of the tire shoulder horizontal furrow (8) is gradually increased, the ratio Wo/Wi of the furrow width (Wo) at the grounding terminal (Te) to the furrow width (Wi) at the part communicated with the tire shoulder longitudinal furrow (3) is 1.5-3.0. One party side furrow intersection part (20) of a one party side furrow wall (8A) of the tire shoulder horizontal furrow (8) in the tire shoulder horizontal furrow (8) and the tire shoulder longitudinal furrow (3) is closer to the axial inner side of the tire than the other party side furrow intersection part (21) of the other party side furrow wall (8B) of the tire shoulder horizontal furrow (8) in the tire shoulder horizontal furrow (8) and the tire shoulder longitudinal furrow (3).

Description

  The present invention relates to a pneumatic tire that improves mud performance while suppressing deterioration of noise performance.

  For example, in an all-season tire traveling on a mud road surface, a block pattern in which a plurality of blocks are divided into a tread portion by a plurality of main grooves extending in the tire circumferential direction and a plurality of lateral grooves extending in the tire axial direction. Is adopted. Conventionally, in order to improve the mud performance, it is known to increase the depth and width of the main groove and the lateral groove to increase the soil removal performance and the shearing force for shearing the mud compacted in the lateral groove.

  However, in the above-described method, the groove volume of the main groove and the lateral groove increases, and the resonance vibration (air column resonance sound) of the air generated in the groove increases, and noise performance deteriorates when traveling on a dry road surface. There was a problem. Thus, there is a tradeoff between improving the mud performance and ensuring the noise performance, and it has been difficult to achieve both. Related technologies include the following.

JP 2004-58839 A

  The present invention has been devised in view of the above problems, and based on improving the shape of the shoulder vertical groove and the shoulder horizontal groove, the noise performance is minimized and the mud performance is improved. The main purpose is to provide a pneumatic tire.

The invention according to claim 1 of the present invention is such that the tread portion is provided with a shoulder vertical groove that extends most on the ground contact end side in the tire circumferential direction, and a shoulder horizontal groove that extends from the shoulder vertical groove beyond the ground contact end. A pneumatic tire in which a shoulder block row in which shoulder blocks are spaced apart in the tire circumferential direction is formed, wherein the shoulder longitudinal groove includes an outer groove portion extending outward in the tire axial direction along the tire circumferential direction, A trapezoidal wave-shaped zigzag including an inner groove portion extending in the tire axial direction from the groove portion along the tire circumferential direction and a transition portion extending obliquely from the inner groove portion to the outer groove portion, and the shoulder lateral groove in the tire axial direction And an intersection P1 where the groove center line intersects the shoulder longitudinal groove, and an intersection of the groove center line and the grounding end Angle with respect to the tire axial direction of a straight line connecting the 2 is 5 to 20 degrees, the shoulder lateral grooves, said extending from the shoulder longitudinal groove linearly to said ground terminal, and the groove width towards the axially outside Gradually increases, the ratio Wo / Wi of the groove width Wi at the communicating portion with the shoulder vertical groove and the groove width Wo at the ground contact end is 1.5 to 3.0, and the shoulder lateral groove is The groove crossing portion on one side where the groove wall on one side of the shoulder horizontal groove and the shoulder vertical groove intersect is more than the groove crossing portion on the other side where the groove wall on the other side of the shoulder horizontal groove and the shoulder vertical groove intersects. It is located inside the tire axial direction.

  The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the groove intersection on the one side is located on the inner groove and the groove intersection on the other side is located on the outer groove. is there.

  According to a third aspect of the present invention, the groove intersecting portion on the one side is located at an end of the inner groove portion on the transition portion side, and the groove intersecting portion on the other side is located on the transition portion side of the outer groove portion. It is a pneumatic tire of Claim 2 located in an edge part.

  In the invention according to claim 4, the ratio Wr / Wg between the groove width Wg of the transition portion and the communication width Wr of the shoulder lateral groove to the transition portion is 0.8 to 1.8. It is a pneumatic tire.

  In the invention according to claim 5, the shoulder longitudinal groove has a protruding amount Ld which is a tire axial direction distance from a groove edge on the outer side in the tire axial direction of the inner groove portion to a groove edge on the outer side in the tire axial direction of the outer groove portion. The pneumatic tire according to any one of claims 1 to 4, which is 0.4 to 0.8 times the width Lo of the outer groove portion in the tire axial direction.

  According to a sixth aspect of the present invention, the shoulder block row is formed substantially symmetric with respect to a point on the tire equator except for a variable pitch. It is a pneumatic tire.

  In the invention according to claim 7, the shoulder lateral groove is inclined toward the rear arrival side in the tire rotation direction, and the groove wall on the one side is a groove wall on the rear arrival side in the tire rotation direction of the shoulder lateral groove. The pneumatic tire according to any one of claims 1 to 5, wherein the groove wall on the other side is a groove wall on the first arrival side in the tire rotation direction of the shoulder lateral groove.

  In the pneumatic tire of the present invention, a shoulder block is provided on the tread portion by providing a shoulder vertical groove extending in the tire circumferential direction on the most grounded end side and a shoulder horizontal groove extending from the shoulder vertical groove beyond the grounded end. It is spaced apart in the tire circumferential direction. The shoulder longitudinal groove includes an outer groove portion extending along the tire circumferential direction on the outer side in the tire axial direction, an inner groove portion extending along the tire circumferential direction on the inner side in the tire axial direction from the outer groove portion, and from the inner groove portion to the outer groove portion. It forms a trapezoidal wave-shaped zigzag including a transition part extending diagonally. Since the shoulder longitudinal groove including such a transition portion extending obliquely becomes easier to grip mud in the groove, the shearing force against the mud pressed in the groove is increased. Therefore, the pneumatic performance of the present invention improves the mud performance.

  Further, the shoulder lateral groove is inclined to one side with respect to the tire axial direction, and connects an intersection P1 where the groove center line intersects the shoulder longitudinal groove and an intersection P2 between the groove center line and the ground contact end. The angle with respect to the straight tire axial direction is formed at 5 to 20 degrees. Such a pneumatic tire uses the above-mentioned angle to easily discharge mud in the shoulder longitudinal groove to the shoulder lateral groove side, further improve the mud performance, and also provides great traction performance due to the edge effect of the shoulder lateral groove in the tire axial direction. Is secured.

  Further, the shoulder lateral groove has a groove width gradually increasing toward the outer side in the tire axial direction, and a ratio Wo / Wi of the groove width Wi at the communicating portion with the shoulder vertical groove and the groove width Wo at the ground contact end is It is set to 1.5 to 3.0. Such a shoulder lateral groove efficiently guides the mud in the shoulder lateral groove toward the grounding end side in order to increase the pressure on the tire equator C side and decrease the pressure on the grounding end side with respect to the mud in the groove. Therefore, the pneumatic tire of the present invention is further improved in soil removal properties and improved mud performance.

  Further, the shoulder lateral groove is a groove intersecting portion on one side where the groove wall on one side of the shoulder lateral groove intersects with the shoulder vertical groove, and the other side on which the groove wall on the other side of the shoulder lateral groove intersects with the shoulder vertical groove. It is located on the inner side in the tire axial direction than the groove intersection. Accordingly, a pressure difference is generated between the groove crossing portion on the one side and the groove crossing portion on the other side, so that mud in the shoulder vertical groove is smoothly guided into the shoulder horizontal groove. Therefore, the pneumatic tire of the present invention has a large soil removal property and shearing force, and the mud performance is further improved.

It is an expanded view of the tread part which shows the pneumatic tire of one Embodiment of this invention. It is an enlarged view of the left half of FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is an expanded view of the tread part of other embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pneumatic tire of this embodiment (hereinafter, simply referred to as “tire”) is preferably used as an all-season tire for a four-wheel drive vehicle, for example, and a tread portion thereof. 2, a pair of shoulder vertical grooves 3 extending continuously in the tire circumferential direction on the most ground contact end Te side, and a pair of centers extending continuously in the tire circumferential direction on the tire equator C side from the shoulder vertical grooves 3. A longitudinal groove 4 is provided. As a result, the tread portion 2 has a pair of shoulder land portions 5 extending between the shoulder longitudinal groove 3 and the ground contact Te, and a pair of middle land portions extending between the center longitudinal groove 4 and the shoulder longitudinal groove 3. A portion 6 and a pair of center land portions 7 extending between the pair of center longitudinal grooves 4 and 4 are formed.

  Here, the “grounding end” Te is obtained when a normal load is loaded on a normal rim that is assembled with a normal rim and filled with a normal internal pressure, and a normal load is applied to a flat surface with a camber angle of 0 degrees. Is defined as the ground contact position on the outermost side in the tire axial direction. The distance in the tire axial direction between the ground contact Te and Te is determined as the ground contact width TW. Further, the dimensions and the like of each part of the tire are values in the normal state unless otherwise specified.

  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, “Standard Rim” for JATMA and “Design Rim” for TRA. For ETRTO, use "Measuring Rim".

  The “regular internal pressure” is the air pressure defined by each standard for each tire in the standard system including the standard on which the tire is based, and is “maximum air pressure” for JATMA and table for TRA. The maximum value described in TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES is "INFLATION PRESSURE" for ETRTO, but 180 kPa for tires for passenger cars.

  Furthermore, “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “Maximum load capacity” for JATMA, “TIRE” for TRA The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is “LOAD CAPACITY” in the case of ETRTO.

  2, the center land portion 7 has a center lug groove 12 extending in the tire axial direction from the center longitudinal groove 4 toward the tire equator C and terminating without reaching the tire equator C. Provided.

  Further, the middle land portion 6 includes a middle outer lug groove 10 which is inclined inward from the shoulder longitudinal groove 3 toward the inner side in the tire axial direction and terminates without contacting the center longitudinal groove 4. A first inner lug groove 11A that inclines toward the outer side in the axial direction and terminates without contacting the shoulder vertical groove 3, and extends from the center vertical groove 4 to the outer side in the tire axial direction along the tire axial direction and along the shoulder vertical direction. A second middle lug groove 11B that terminates without contacting the groove 3 is spaced apart in the tire circumferential direction.

  As shown in FIG. 2, the shoulder land portion 5 is provided with shoulder lateral grooves 8 extending from the shoulder longitudinal grooves 3 beyond the ground contact Te in the tire circumferential direction. Thus, the shoulder land portion 5 is formed with a block row 9R in which a plurality of shoulder blocks 9 divided by the shoulder vertical groove 3, the ground contact Te and the shoulder horizontal groove 8 are arranged in the tire circumferential direction.

  The tread pattern of the present embodiment is formed substantially in point symmetry with an arbitrary point on the tire equator C as the center except for the variable pitch.

  As shown in FIGS. 2 and 3, the shoulder longitudinal groove 3 includes an outer groove portion 13 extending outside in the tire axial direction along the tire circumferential direction, and an inner side in the tire axial direction along the tire circumferential direction from the outer groove portion 13. A trapezoidal wave-shaped zigzag including an extending inner groove portion 14 and a transition portion 15 extending obliquely from the inner groove portion 14 to the outer groove portion 13 is formed. Since the transition portion 15 extending obliquely has a tire axial direction component, it becomes easy to grip mud in the groove of the transition portion 15 and obtains a large shearing force with respect to the mud pressed in the groove. be able to. Moreover, the outer side groove part 13 and the inner side groove part 14 which extend along a tire circumferential direction are useful for improving a soil removal property.

  The transition portion 15 of the present embodiment includes a first transition piece 15A extending from the inner groove portion 14 to the outer groove portion 13 inclining to one side (upward to the left in the figure) with respect to the tire axial direction, and the first transition piece 15A. And a second transition piece 15B extending in a reverse direction (in this figure, rising to the right). That is, in the shoulder longitudinal groove 3 of the present embodiment, the outer groove portion 13, the first transition piece 15A, the inner groove portion 14 and the second transition piece 15B are successively formed in the trapezoidal wave shape.

  As shown in FIG. 3, the shoulder longitudinal groove 3 is a tire axial distance from the groove edge 14 e on the outer side in the tire axial direction of the inner groove 14 to the groove edge 13 e on the outer side in the tire axial direction of the outer groove 13. The protruding amount Ld is preferably formed to be 0.4 to 0.8 times the width Lo of the outer groove portion 13 in the tire axial direction. That is, if the protruding amount Ld is smaller than 0.4 times the width Lo, the shearing force may be reduced. Conversely, if the protruding amount Ld exceeds 0.8 times, the rigidity of the shoulder block 9 is reduced. In addition to the possibility that the uneven wear performance is deteriorated, the air column resonance generated in the shoulder longitudinal groove 3 is easily discharged to the contact end Te side, so that the noise performance may be deteriorated. For this reason, in particular, the protruding amount Ld is more preferably 0.6 times or more of the width Lo in the tire axial direction, and more preferably 0.7 times or less.

  Further, in order to exhibit the above-described function more effectively, as shown in FIG. 2, the angle θ1 of the groove center line 15G of the transition portion 15 with respect to the tire axial direction is preferably 35 degrees or more, more preferably 40 degrees. The above is desirable, preferably 55 degrees or less, more preferably 50 degrees or less.

  In order to improve the mud performance, traction performance and uneven wear resistance in a well-balanced manner, the ratio La / Lc between the length La of the outer groove 13 in the tire circumferential direction and the length Lc is preferably 0.8 or more. More preferably, it is 1.0 or more, preferably 1.8 or less, more preferably 1.5 or less. From the same viewpoint, the ratio Lb / Lc between the length Lb of the inner groove 14 in the tire circumferential direction and the length Lc of the transition portion 15 in the tire circumferential direction is preferably 0.6 or more, more preferably 0.9 or more. Is desirable, preferably 1.5 or less, more preferably 1.2 or less.

  Further, the center longitudinal groove 4 of the present embodiment also has an outer groove portion 17 extending along the tire circumferential direction along the tire axial direction, and an inner side extending along the tire axial direction along the tire circumferential direction, like the shoulder longitudinal groove 3. A trapezoidal wave-shaped zigzag including a groove portion 18 and a transition portion 19 extending obliquely from the inner groove portion 18 to the outer groove portion 17 is formed. Thereby, also in a crown part, mud performance, traction performance, and uneven wear-proof performance improve.

  The width of the shoulder vertical groove 3 and the center vertical groove 4 (the groove width perpendicular to the longitudinal direction of the groove, the same applies to other grooves hereinafter) W1, W2 and groove depths D1, D2 ( (Not shown) can be variously determined according to common practice. However, if the groove widths W1 and W2 and / or the groove depths D1 and D2 are too large, noise performance and rigidity of the land portions 5 and 6 may be reduced. Performance may be reduced. For this reason, the groove widths W1 and W2 are preferably 3.0 to 8.0% of the grounding width TW, for example. The groove depths D1 and D2 are preferably 8.0 to 10.0 mm.

  As for the position of the shoulder longitudinal groove 3, for example, the tire axial distance L1 between the amplitude center line 3G and the ground contact Te is preferably 16% or more, more preferably 20% or more of the ground contact width TW. Is desirable, preferably 30% or less, and more preferably 26% or less. Further, with respect to the position where the center longitudinal groove 4 is disposed, for example, the tire axial distance L2 between the groove center line 4G and the tire equator C is preferably 3% or more of the contact width TW, more preferably 5% or more. Is desirable, preferably 14% or less, more preferably 10% or less. By setting to such a range, the rigidity balance of the land portions 5, 6 and 7 can be further improved, and uneven wear resistance can be improved.

  As shown in FIG. 2, the shoulder lateral groove 8 extends linearly from the shoulder longitudinal groove 3 to the ground contact Te in the present embodiment. Such a shoulder lateral groove 8 is useful for smoothly discharging mud in the shoulder lateral groove 8 toward the ground contact Te, and also for ensuring a large rigidity of the shoulder block 9.

  Further, the shoulder lateral groove 8 is inclined to one side (upward to the left in the figure) with respect to the tire axial direction. Further, the shoulder lateral groove 8 has an angle θ2 with respect to the tire axial direction of a straight line connecting an intersection P1 where the groove center line 8G intersects the shoulder longitudinal groove 3 and an intersection P2 between the groove center line 8G and the ground contact Te. Is formed at 5 to 20 degrees. As a result of various experiments, when the angle θ2 is less than 5 degrees, the mud in the shoulder longitudinal groove 3 cannot be smoothly discharged to the shoulder lateral groove 8 side, and the mud performance is deteriorated. Since it becomes large, noise performance deteriorates. On the other hand, when the angle θ2 exceeds 20 degrees, the edge effect in the tire axial direction is lowered and the traction performance is deteriorated. Therefore, the angle θ2 is more preferably 8 degrees or more, and more preferably 17 degrees or less. The intersection point P1 is defined as an intersection point between the groove edge 3A and the groove center line 8G when the groove edge 3A of the shoulder longitudinal groove 3 where the shoulder lateral groove 8 intersects is clearly represented. However, when the groove edge 3A is unclear, the virtual groove edge (not shown) and the groove center line 8G when the groove edge 3B inside the tire longitudinal direction of the shoulder longitudinal groove 3 is projected onto the groove edge 3A. Defined as the intersection of

  Further, the shoulder lateral groove 8 gradually increases in the groove width W3 toward the outer side in the tire axial direction. Specifically, in the shoulder lateral groove 8, the ratio Wo / Wi of the groove width Wi at the communicating portion with the shoulder vertical groove 3 and the groove width Wo at the ground contact Te is set to 1.5 to 3.0. The As a result of various experiments, when the ratio Wo / Wi is less than 1.5, it is not possible to give a pressure difference to the mud in the shoulder lateral groove 8, and the soil removal effect using the pressure difference is sufficiently exhibited. Can not do it. On the contrary, if the ratio Wo / Wi exceeds 3.0, the air column resonance generated in the shoulder longitudinal groove 3 is easily discharged to the grounding end Te side, the noise performance is deteriorated, and the rigidity of the shoulder block 9 is increased. Becomes smaller and uneven wear resistance deteriorates. From this viewpoint, the ratio Wo / Wi is more preferably 2.0 or more, and more preferably 2.5 or less.

  Further, the shoulder lateral groove 8 has a groove intersecting portion 20 on one side where the groove wall 8A (upper side in FIG. 2) of the shoulder lateral groove 8 and the shoulder vertical groove 3 intersect with each other. It is located on the inner side in the tire axial direction with respect to the groove intersecting portion 21 on the other side where the wall 8B (lower side in FIG. 2) and the shoulder longitudinal groove 3 intersect. Such a shoulder lateral groove 8 has a difference in pressure acting on the mud at the groove intersecting portion 20 on the one side and the groove intersecting portion 21 on the other side. It can be smoothly guided into the shoulder lateral groove 8. Therefore, the tire of the present invention has a large soil removal property and shearing force, and the mud performance is further improved.

  In order to ensure the above-described effect, it is desirable that the groove intersection 20 on one side is located on the inner groove 14 and the groove intersection 21 on the other side is located on the outer groove 13. Since such a shoulder lateral groove 8 has a large communication width (not shown) to the transition portion 15 of the shoulder lateral groove 8, mud in the shoulder longitudinal groove 3 can be smoothly guided to the shoulder lateral groove 8. The soil removal and shearing force are further enhanced.

  Further, in the shoulder lateral groove 8, the groove intersecting portion 20 on one side is located at the end portion 14t of the inner groove portion 14 on the side of the transition portion 15 (second transition piece 15B in FIG. 2) and the groove on the other side. More preferably, the intersecting portion 21 is located at the end portion 13t of the outer groove portion 13 on the transition portion 15 (second transition piece 15B in FIG. 2) side. That is, in the present embodiment, the shoulder lateral groove 8 is connected over the entire length of the groove edge 15E on the outer side in the tire axial direction of the second transition piece 15B. Thereby, since the above-mentioned pressure difference can be secured while suppressing discharge of air column resonance from the shoulder longitudinal groove 3, the mud performance and the noise performance are improved in a well-balanced manner.

  In particular, the shoulder lateral groove 8 is preferably inclined toward the rear arrival side in the tire rotation direction. That is, the groove wall 8A on the one side forms a groove wall on the rear arrival side of the tire lateral direction of the shoulder lateral groove 8, and the groove wall 8B on the other side is on the first arrival side of the shoulder lateral groove 8 in the tire rotational direction. It is desirable to form a groove wall. Such shoulder lateral grooves 8 are sequentially grounded from the inner side to the outer side in the tire axial direction due to rolling of the tire, so that mud is likely to enter when entering the ground, and mud is easily discharged when coming out from the ground. That is, since the shoulder lateral groove 8 secures a large amount of mud in the groove of the shoulder lateral groove 8 from the time of entering the ground to the time of coming out of the ground, a large shearing force is exerted, and the earth discharging property is greatly increased when coming out of the ground. Works. Therefore, the tire performance of the present embodiment further improves the mud performance.

  Further, in the tire in which the shoulder lateral grooves 8 are inclined toward the tire arrival direction rear arrival side, the other-side groove intersection portion 21 is the first arrival side with respect to the one-side groove intersection portion 20 located on the inner side in the tire axial direction. Therefore, as shown by an arrow A in FIG. 2, the mud in the shoulder longitudinal groove 3 is smoothly discharged to the shoulder lateral groove 8 side as the tire rolls. Therefore, more mud is secured in the shoulder lateral groove 8 at the time of grounding, and a greater shearing force is exhibited, so that the mud performance is further improved.

  As shown in FIG. 3, the ratio Wr / Wg of the groove width Wg of the transition portion 15 and the communication width Wr of the shoulder lateral groove 8 to the transition portion 15 is preferably 0.8 to 1.8. When the ratio Wr / Wg increases, the groove width W3 of the shoulder lateral groove 8 increases, and the air column resonance noise of the shoulder vertical groove 3 may not be suppressed. Conversely, if the ratio Wr / Wg is small, it may be difficult to discharge mud from the shoulder vertical groove 3 to the shoulder horizontal groove 8. From such a viewpoint, the ratio Wr / Wg is more preferably 1.0 or more, and more preferably 1.6 or less. The communication width Wr of the transition portion 15 is defined as the shortest distance between the groove crossing portion 20 on the one side and the groove crossing portion 21 on the other side.

  The width W3 of the shoulder lateral grooves 8 (average groove width in the length direction of the shoulder lateral grooves 8) is preferably 9.5 to 10.5 mm, for example, from the viewpoint of achieving both mud performance and noise performance. . Further, the groove depth D3 (not shown) of the shoulder lateral groove 8 is desirably 80 to 100% of the groove depth D1 of the shoulder vertical groove 3, for example.

  Also, the shoulder block 9 has a shoulder lug groove extending from the intersection 13A of the second transition piece 15B and the outer groove 13 toward the outer side in the tire axial direction along the tire axial direction and ending without reaching the ground contact end Te. 22 is provided. Such a shoulder lug groove 22 is useful for improving the traction performance.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, it cannot be overemphasized that this invention can be deform | transformed and implemented in various aspects, without being limited to embodiment of illustration.

Pneumatic tires (size: 285 / 60R18) having the pattern of FIG. 1 and based on the specifications in Table 1 were manufactured and tested for their respective performance. The common specifications are as follows.
Grounding width TW: 200mm
<Shoulder main groove>
Groove width W1 / Grounding width TW: 3.1%
Groove depth D1: 10.0 mm
Angle θ1: 45 degrees with respect to the tire axial direction of the transition portion Ratio of length in the tire circumferential direction between the inner groove portion and the outer groove portion La / Lb: 1.17
<Center main groove>
Groove width W2 / Contact width TW: 4.1%
Groove depth D2: 10.0mm
Angle relative to the tire axial direction of the center transition part: 40 degrees <shoulder lateral groove>
Groove depth D3 / D1: 90%
<Middle outer lug groove / first middle lug groove>
Groove depth 5.0-8.0mm
<Shoulder lug groove, 2nd middle lug groove, center lug groove 12>
Groove depth 3.0-5.0mm
The test method is as follows.

<Noise performance>
A sample tire is mounted on all wheels of a vehicle (domestic 4600cc, 4WD vehicle) under the conditions of a rim 18 × 8.5JJ and internal pressure (230 kPa), and the road noise measurement path (asphalt rough road) at a speed of 60 km / h. In-car noise during driving was collected with a microphone installed at the driver's seat window side ear position, and the sound pressure level of the peak value of the air column resonance sound in the narrow band around 240 Hz was measured. The evaluation is shown by an index with the reciprocal of Comparative Example 1 being 100, and the larger the value, the better.

<Mad performance>
The driver was driven on the soft mud road test course with the above-mentioned vehicle mounted, and the braking force, turning performance, etc. were evaluated comprehensively based on the driver's sensitivity. The evaluation is represented by a score with Comparative Example 1 being 100, and the larger the value, the better.

<Traction performance>
The degree of transmission of the driving force to the road surface on the same test course under the above vehicle conditions by a professional test driver was displayed with a score of Comparative Example 1 as 100 due to the driver's feeling. The larger the value, the better.

<Uneven wear resistance>
In the above vehicle, a dry asphalt tire test course was run for 30 km by limit running, and the presence or absence of ribs, blocks, uneven wear, etc. were visually observed. The evaluation is indicated by a score with Comparative Example 1 being 100, and the larger the numerical value, the better the uneven wear resistance.
The test results are shown in Table 1.

  As a result of the test, it can be confirmed that the tires of the examples have improved various performances as compared with the comparative examples.

2 tread portion 3 shoulder vertical groove 8 shoulder lateral groove 8A groove wall on one side 8B groove wall on the other side 8G groove center line of shoulder lateral groove 9 shoulder block 9R shoulder block row 13 outer groove portion 14 inner groove portion 15 transition portion 20 groove on one side Crossing portion 21 Other side groove crossing portion Te Grounding end

Claims (7)

A shoulder block is provided in the tire circumferential direction by providing a shoulder vertical groove extending in the tire circumferential direction on the tread portion and a shoulder horizontal groove extending from the shoulder vertical groove beyond the grounded end in the tire circumferential direction. A pneumatic tire in which a shoulder block row is formed,
The shoulder longitudinal groove includes an outer groove portion extending in the tire circumferential direction on the outer side in the tire axial direction, an inner groove portion extending in the tire axial direction on the inner side in the tire axial direction from the outer groove portion, and the outer groove portion from the inner groove portion. A trapezoidal wave-shaped zigzag including a transition part extending diagonally
The shoulder lateral groove is inclined to one side with respect to the tire axial direction, and a straight line connecting an intersection point P1 where the groove center line intersects the shoulder longitudinal groove and an intersection point P2 between the groove center line and the ground contact end. The angle with respect to the tire axial direction is 5 to 20 degrees,
The shoulder lateral groove extends linearly from the shoulder longitudinal groove to the ground contact end, and the groove width gradually increases toward the outer side in the tire axial direction, the groove width Wi at the communicating portion with the shoulder longitudinal groove, The ratio Wo / Wi to the groove width Wo at the ground contact end is 1.5 to 3.0,
In addition, the shoulder lateral groove has a groove intersection portion on one side where the groove wall on one side of the shoulder lateral groove and the shoulder vertical groove intersect, and the other side on which the groove wall on the other side of the shoulder lateral groove and the shoulder vertical groove intersect. A pneumatic tire characterized by being located on the inner side in the tire axial direction from the groove intersection portion.
  2. The pneumatic tire according to claim 1, wherein the groove crossing portion on the one side is located on the inner groove portion and the groove crossing portion on the other side is located on the outer groove portion.   The groove crossing portion on the one side is located at an end portion of the inner groove portion on the transition portion side, and the groove crossing portion on the other side is located at an end portion of the outer groove portion on the transition portion side. Pneumatic tires.   The pneumatic tire according to claim 3, wherein a ratio Wr / Wg of a groove width Wg of the transition portion to a communication width Wr of the shoulder lateral groove to the transition portion is 0.8 to 1.8.   The shoulder longitudinal groove has a protruding amount Ld which is a distance in the tire axial direction from a groove edge on the outer side in the tire axial direction of the inner groove portion to a groove edge on the outer side in the tire axial direction of the outer groove portion in the tire axial direction of the outer groove portion. The pneumatic tire according to any one of claims 1 to 4, which is 0.4 to 0.8 times the width Lo.   The pneumatic tire according to any one of claims 1 to 5, wherein the shoulder block row is formed substantially in point symmetry except for a variable pitch with an arbitrary point on the tire equator as a center. The shoulder lateral groove is inclined toward the tire arrival direction rear arrival side,
The groove wall on the one side is a groove wall on the rear arrival side of the shoulder lateral groove in the tire rotation direction, and the groove wall on the other side is a groove wall on the first arrival side in the tire rotation direction of the shoulder lateral groove. Item 6. The pneumatic tire according to any one of Items 1 to 5.

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