CN102729736B - Air-inflation tyre - Google Patents

Abstract

The pneumatic tire of the present invention suppresses deterioration of noise performance and improves mud performance. The pneumatic tire (1) is provided with a shoulder longitudinal groove (3) and a shoulder transverse groove (8). The shoulder longitudinal grooves (3) are formed as trapezoidal wavy serrations. In the shoulder transverse groove (8), connect the intersection point (P1) where the groove centerline (8G) intersects with the shoulder longitudinal groove (3), and the intersection point (P2) where the groove centerline (8G) intersects the ground end (Te) The angle between the straight line and the axial direction of the tire is 5-20 degrees. The groove width of the shoulder lateral groove (8) gradually increases, and the ratio of the groove width (Wo) at the ground contact point (Te) to the groove width (Wi) at the connecting portion with the shoulder longitudinal groove (3) Wo/Wi is 1.5-3.0. Among the shoulder transverse grooves (8), the groove wall (8A) on one side of the shoulder transverse groove (8) intersects with the shoulder longitudinal groove (3), and the groove intersection (20) on one side is located (8) The groove wall (8B) on the other side intersects the shoulder longitudinal groove (3) and the groove intersection portion (21) on the other side is located further inward in the tire axial direction.

Description

pneumatic tire

technical field

The present invention relates to a pneumatic tire that suppresses deterioration of noise performance and improves mud road performance.

Background technique

For example, four-season general-purpose tires running on muddy roads use a block pattern. pattern blocks. Conventionally, in order to improve the performance of mud roads, it is known to increase the depth and width of the main trenches and lateral trenches to improve the soil-discharging performance, or to cut the shearing force of the mud compacted in the transverse trenches.

However, in the above-mentioned method, since the groove volume of the main groove and the lateral groove is increased, the resonant vibration of the air (air column resonance sound) generated in the groove is increased, so that there is a problem that the noise performance deteriorates when driving on a dry road surface. . In this way, improving the mud road performance and ensuring the noise performance are contradictory, and it is difficult to balance both. Related techniques are as follows.

Patent Document 1: JP Unexamined Patent Application Publication No. 2004-58839

Contents of the invention

The present invention has been made in view of the above problems, and its main object is to provide a tire that can improve performance on muddy roads by suppressing deterioration of noise performance to a minimum by improving the shape of the shoulder longitudinal groove and the shoulder lateral groove. Pneumatic tires.

The invention described in claim 1 of the present invention is a pneumatic tire in which a shoulder longitudinal groove extending in the tire circumferential direction on the side closest to the ground contact end, and a shoulder longitudinal groove extending over the ground contact from the above shoulder longitudinal groove are provided on the tread portion. The shoulder lateral grooves extending from the ends of the tire are formed on the tread portion with shoulder block rows arranged at intervals along the tire circumferential direction. The pneumatic tire is characterized in that the above-mentioned shoulder longitudinal grooves are formed including outer Trapezoidal wavy serrations of the groove, the inner groove, and the transition portion, the outer groove extending in the tire circumferential direction on the tire axially outer side, the inner groove extending in the tire axially inner side than the outer groove in the tire circumferential direction Extending, the transition portion extends obliquely from the inner groove portion to the outer groove portion and includes: a first transition piece extending obliquely from the inner groove portion to the outer groove portion to one side with respect to the tire axial direction; In the second transition piece extending obliquely in the opposite direction to the first transition piece, the shoulder lateral groove is inclined to one side with respect to the tire axial direction, and the intersection point P1 where the groove center line intersects the shoulder longitudinal groove, The straight line connecting the intersection point P2 of the center line of the groove and the ground contact end has an angle of 5 to 20 degrees with respect to the tire axial direction, and the shoulder lateral groove extends linearly from the shoulder longitudinal groove to the ground contact end, and The groove width gradually increases toward the outside in the tire axial direction, and the ratio Wo of the groove width Wo of the shoulder lateral groove at the ground contact end and the groove width Wi of the connecting portion of the shoulder lateral groove and the shoulder longitudinal groove is /Wi is 1.5 to 3.0, and among the above-mentioned shoulder lateral grooves, the groove intersecting portion on the one side where the groove wall on one side of the shoulder lateral groove intersects the above-mentioned shoulder longitudinal groove is located on the other side of the above-mentioned shoulder lateral groove. The groove wall on one side intersects the shoulder longitudinal groove and the groove intersection on the other side is closer to the inner side of the tire axial direction, and the shoulder lateral groove is connected to the entire length of the axially outer bezel of the second transition piece. .

In addition, in the invention described in claim 2, in the pneumatic tire described in claim 1, the groove intersecting portion on the one side is located on the inner groove portion, and the groove intersecting portion on the other side is located on the outer groove. department.

In addition, in the invention described in claim 3, in the pneumatic tire described in claim 2, the groove intersecting portion on the one side is located at the end portion of the inner groove portion on the transition portion side, and the groove on the other side is The groove intersection portion is located at an end portion of the outer groove portion on the transition portion side.

In addition, in the invention described in claim 4, in the pneumatic tire described in claim 3, the ratio Wr/Wg of the communication width Wr of the shoulder lateral groove to the transition portion to the groove width Wg of the transition portion is 0.8 to 1.8.

Furthermore, in the invention described in claim 5, in the pneumatic tire described in any one of claims 1 to 4, in the shoulder longitudinal groove, the tire axially outer bezel of the inner groove portion to The axial distance from the axially outer bezel of the outer groove portion, that is, the projection amount Ld, is 0.4 to 0.8 times the axial width Lo of the outer groove portion.

In addition, in the invention described in claim 6, in the pneumatic tire described in any one of claims 1 to 4, the above-mentioned shoulder block row is formed so as to be centered on an arbitrary point on the tire equator. It is substantially point-symmetric except for the variable pitch.

In addition, in the invention described in claim 7, in the pneumatic tire described in any one of claims 1 to 4, the shoulder lateral groove is inclined toward the rear landing side in the tire rotation direction, and the groove wall on the one side is The shoulder lateral groove is a groove wall on the rear landing side in the tire rotation direction, and the other groove wall is a groove wall on the front landing side in the tire rotation direction of the shoulder lateral groove.

In the pneumatic tire of the present invention, the tread is provided with a shoulder longitudinal groove extending in the tire circumferential direction on the side closest to the ground contact end, and a shoulder lateral groove extending from the shoulder longitudinal groove across the ground contact end, and the tire The shoulder pattern blocks are arranged at intervals in the circumferential direction. The shoulder longitudinal groove forms trapezoidal wavy sawtooth including an outer groove portion, an inner groove portion and a transition portion, wherein the outer groove portion extends along the tire circumferential direction outside the tire axial direction, and the inner groove portion is closer to the tire than the outer groove portion. The axially inner side extends in the tire circumferential direction, and the transition portion extends obliquely from the inner groove portion to the outer groove portion. The shoulder longitudinal groove including such an obliquely extending transition portion improves the shearing force of the mud compacted in the groove because it is easy to catch the mud in the groove. Therefore, the pneumatic tire of the present invention can improve performance on mud roads.

In addition, the shoulder lateral groove is inclined to one side with respect to the tire axial direction, and the straight line connecting the intersection point P1 where the groove centerline intersects the above-mentioned shoulder longitudinal groove and the intersection point P2 where the groove centerline and the above-mentioned ground contact edge intersects is opposite to the The angle in the tire axial direction is formed at 5 to 20 degrees. This pneumatic tire utilizes the above-mentioned angle to easily discharge the mud in the shoulder longitudinal groove to the side of the shoulder lateral groove, further improving the performance on muddy roads, and utilizes the edge effect of the tire axial direction of the shoulder lateral groove to ensure greater traction performance.

Further, the shoulder lateral groove gradually increases in groove width toward the tire axially outer side, and the ratio Wo/Wi of the groove width Wo at the above-mentioned ground contact end to the groove width Wi at the communicating portion of the above-mentioned shoulder longitudinal groove is set as 1.5～3.0. Such shoulder lateral grooves effectively guide the mud in the shoulder lateral grooves toward the ground contact end by increasing the pressure on the equator C side of the tire and reducing the pressure on the ground contact end side for the mud in the groove. Therefore, the pneumatic tire of the present invention further improves the earth-discharging property and improves the mud road performance.

In addition, among the shoulder lateral grooves, the groove intersecting portion on one side where the groove wall on one side of the shoulder lateral groove intersects the above-mentioned shoulder longitudinal groove is located more than the groove wall on the other side of the above-mentioned shoulder lateral groove intersects the above-mentioned tire. The groove intersecting portion on the other side where the shoulder longitudinal grooves intersect is closer to the inner side in the tire axial direction. Accordingly, since a pressure difference is generated between the groove intersecting portion on one side and the intersecting portion on the other side, the mud in the shoulder longitudinal groove is smoothly guided into the shoulder lateral groove. Therefore, the pneumatic tire of the present invention increases soil-discharging performance and shearing force, and further improves performance on mud roads.

Description of drawings

FIG. 1 is a developed view showing a tread portion of a pneumatic tire according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the left half of FIG. 1 .

FIG. 3 is a partially enlarged view of FIG. 2 .

Fig. 4 is a developed view of a tread portion according to another embodiment of the present invention.

Explanation of Reference Signs: 2...tread portion; 3...shoulder longitudinal groove; 8...shoulder transverse groove; 8A...groove wall on one side; 8B...groove wall on the other side; 8G...groove center of shoulder transverse groove Line; 9...shoulder block; 9R...shoulder block row; 13...outer groove; 14...inner groove; 15...transition; 20...groove intersection on one side; 21...groove on the other side Intersection; Te... ground terminal.

detailed description

Hereinafter, one 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, sometimes simply referred to as "tire") is suitable for use as an all-season tire for four-wheel drive vehicles, for example, and the tread portion 2 is provided with: A pair of shoulder longitudinal grooves 3 extending continuously in the tire circumferential direction, and a pair of center longitudinal grooves 4 continuously extending in the tire circumferential direction on the tire equator C side of the shoulder longitudinal grooves 3 . As a result, a pair of shoulder land portions 5 extending between the shoulder longitudinal groove 3 and the ground edge Te and a pair of shoulder land portions 5 extending between the center longitudinal groove 4 and the shoulder longitudinal groove 3 are formed on the tread portion 2 . The middle land portion 6 and the pair of center land portions 7 extending between the pair of center longitudinal grooves 4 , 4 .

Here, the above-mentioned "ground contact end" Te is set to be the maximum point when a normal load is applied to a tire in a normal state with no load and the rim is assembled to a normal rim and filled with a normal internal pressure, and it is grounded on a plane at a camber angle of 0 degrees. The ground contact position on the outer side of the tire axis. Also, the distance in the tire axial direction between the ground contact ends Te, Te is set as the ground contact width TW. In addition, the dimensions and the like of each part of the tire take the value in the normal state described above unless otherwise specified.

In addition, the above-mentioned "regular rim" refers to a rim that specifies each specification for each tire in the specification system including the specification on which the tire is based. In the case of JATMA, it is "standard rim", and in the case of TRA, it is "DesignRim". ", or "MeasuringRim" in the case of ETRTO.

In addition, the "regular internal pressure" mentioned above refers to the air pressure specified for each specification for each tire in the specification system including the specification on which the tire is based. In the case of JATMA, it is the "maximum air pressure", and in the case of TRA, it is It is the maximum value recorded in the table "TIRELOADLIMITSATVARIOUSCOLDINFLATIONPRESSURES", and "INFLATIONPRESSURE" in the case of ETRTO, but 180kPa is taken when the tire is for a car.

In addition, the above-mentioned "regular load" refers to the load specified for each specification for each tire in the specification system including the specification on which the tire is based. In the case of JATMA, it is the "maximum load capacity", and in the case of TRA, it is the table. The maximum value described in "TIRELOADLIMITSATVARIOUSCOLDINFLATIONPRESSURES" is "LOADCAPACITY" in the case of ETRTO, but when the tire is for a passenger car, a load equivalent to 88% of the above load is taken.

As shown enlarged in FIG. 2 , the central land portion 7 is provided with a central lug groove 12 extending in the tire axial direction from the central longitudinal groove 4 toward the tire equator C and not reaching the tire equator C. is to form a terminal.

In addition, in the above-mentioned middle land portion 6, there are arranged at intervals along the tire circumferential direction: middle outer lug grooves 10 which extend obliquely from the shoulder longitudinal groove 3 toward the inner side of the tire axial direction and are not connected to the central longitudinal groove 4 but form a terminal end. the first intermediate inner lug groove 11A extending obliquely toward the tire axially outer side from the central longitudinal groove 4 and not connecting with the shoulder longitudinal groove 3 but forming a terminal; the second intermediate inner lug groove 11B extending from the central The longitudinal groove 4 extends in the tire axial direction toward the outer side in the tire axial direction and is not connected to the shoulder longitudinal groove 3 but forms a terminal end.

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

The tread pattern of the present embodiment is formed substantially point-symmetrically with respect to any point on the tire equator C except for variable pitches.

As shown in FIGS. 2 and 3 , the above-mentioned shoulder longitudinal groove 3 is formed as a trapezoidal wavy sawtooth, including: an outer groove portion 13 extending in the tire circumferential direction on the outside of the tire axial direction, and an outer groove portion 13 closer to the tire axis than the outer groove portion 13 . An inner groove portion 14 extending inward in the tire circumferential direction, and a transition portion 15 obliquely extending from the inner groove portion 14 to the outer groove portion 13 . Since the obliquely extending transition portion 15 has a tire axial component, it is easy to catch the mud in the groove of the transition portion 15, thereby obtaining a large shearing force on the mud compacted in the groove. In addition, the outer groove portion 13 and the inner groove portion 14 extending in the tire circumferential direction contribute to improvement of soil release performance.

The transition portion 15 of this embodiment includes: a first transition piece 15A extending obliquely to one side (upper left in the figure) from the inner groove portion 14 to the outer groove portion 13 with respect to the tire axial direction; The second transition piece 15B extends obliquely in the direction opposite to the transition piece 15A (upper right in the figure). That is, the shoulder longitudinal groove 3 of the present embodiment forms the above-mentioned trapezoidal wave shape by sequentially connecting the outer groove portion 13 , the first transition piece 15A, the inner groove portion 14 , and the second transition piece 15B.

In addition, as shown in FIG. 3 , the shoulder longitudinal groove 3 is formed in the axial direction from the axially outer bezel 14 e of the inner groove portion 14 to the tire axially outer bezel 13 e of the outer groove portion 13 . The distance, that is, the protrusion amount Ld, is 0.4 to 0.8 times the width Lo of the outer groove portion 13 in the tire axial direction. That is, if the overhang amount Ld is less than 0.4 times the above-mentioned width Lo, the shearing force may be reduced. Conversely, if it exceeds 0.8 times, since the rigidity of the shoulder block 9 becomes small, the unevenness may be reduced. The wear performance is deteriorated. In addition, the air column resonance sound generated in the shoulder longitudinal groove 3 is likely to be discharged toward the ground contact edge Te side, so that the noise performance may be deteriorated. Therefore, in particular, the overhang amount Ld is more preferably 0.6 times or more, and more preferably 0.7 times or less, the width Lo in the tire axial direction.

In addition, in order to exert the above-mentioned effect 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 or more, and more preferably 55 degrees. degrees or less, more preferably 50 degrees or less.

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

In addition, the central longitudinal groove 4 of this embodiment is also formed as a trapezoidal wavy serration similarly to the shoulder longitudinal groove 3, and includes: an outer groove portion 17 extending along the tire circumferential direction on the tire axially outer side; An inner groove portion 18 extending in the circumferential direction, and a transition portion 19 obliquely extending from the inner groove portion 18 to the outer groove portion 17 . As a result, mud performance, traction performance, and uneven wear resistance can be improved even in the crown portion.

For such shoulder longitudinal grooves 3 and center longitudinal grooves 4, the groove widths (groove widths at right angles to the longitudinal direction of the grooves, hereinafter, the same applies to other grooves) W1, W2 and groove depths D1, D2 (not shown) ), which can be set to various values by convention. However, if the above-mentioned groove widths W1, W2 and/or groove depths D1, D2 are too large, the noise performance and the rigidity of the land parts 5 and 6 may be reduced. Conversely, if they are too small, it will be difficult to grasp the mud. , it may degrade the mud road performance. Therefore, the trench widths W1 and W2 are preferably, for example, 3.0 to 8.0% of the ground width TW. In addition, the groove depths D1 and D2 are preferably 8.0 to 10.0 mm.

In addition, for the arrangement position of the shoulder longitudinal groove 3, for example, the tire axial distance L1 between the swing center line 3G and the ground contact edge Te is preferably 16% or more of the ground contact width TW, more preferably 20% or more. Preferably it is 30% or less, More preferably, it is 26% or less. In addition, regarding the arrangement position of the central longitudinal groove 4, for example, the tire axial distance L2 between the groove centerline 4G and the tire equator C is preferably 3% or more of the contact width TW, more preferably 5% or more, and is also preferably 14% or less, more preferably 10% or less. By setting in such a range, the rigidity balance of each land part 5, 6, and 7 can be further improved, and uneven wear resistance performance can be improved.

As shown in FIG. 2 , in the present embodiment, the shoulder lateral groove 8 extends linearly from the shoulder longitudinal groove 3 to the ground contact edge Te. Such shoulder lateral grooves 8 contribute to smooth discharge of mud in the shoulder lateral grooves 8 to the ground contact edge Te side, and contribute to ensuring high rigidity of the shoulder blocks 9 .

In addition, the shoulder lateral groove 8 is inclined to one side (upper left in the figure) with respect to the tire axial direction. Furthermore, the shoulder lateral groove 8 is formed as a straight line connecting the intersection point P1 where the groove centerline 8G intersects the shoulder longitudinal groove 3 and the intersection point P2 where the groove centerline 8G and the ground contact edge Te intersect. The axial angle θ2 is 5 to 20 degrees. As a result of various experiments, it was found that if the above-mentioned angle θ2 is less than 5 degrees, the mud in the shoulder longitudinal groove 3 cannot be smoothly discharged to the side of the shoulder lateral groove 8, which deteriorates the mud road performance. At the same time, the ground area of the road surface increases, so the noise performance deteriorates. On the other hand, if the above-mentioned angle θ2 exceeds 20 degrees, the edge effect in the tire axial direction decreases, so that the traction performance deteriorates. Therefore, the above-mentioned angle θ2 is more preferably 8 degrees or more, and more preferably 17 degrees or less. Here, the above-mentioned intersection point P1 is defined as the intersection point of the bezel 3A and the groove centerline 8G when the bezel 3A of the shoulder longitudinal groove 3 intersected by the shoulder lateral groove 8 clearly appears. However, when the bezel 3A is unclear, it is defined as the distance between the virtual bezel (not shown) and the groove centerline 8G when the bezel 3B on the inner side of the shoulder longitudinal groove 3 in the tire axial direction is projected onto the bezel 3A. intersection.

In addition, the shoulder lateral groove 8 gradually increases in groove width W3 toward the outer side in the tire axial direction. Specifically, the ratio Wo/Wi of the groove width Wo at the ground contact edge Te of the shoulder lateral groove 8 to the groove width Wi at the communicating portion with the shoulder longitudinal groove 3 is set to 1.5 to 3.0. As a result of various experiments, it has been found that if the ratio Wo/Wi is less than 1.5, a pressure difference cannot be applied to the mud in the shoulder lateral groove 8, and the soil discharge effect using the pressure difference cannot be sufficiently exerted. Conversely, if the above-mentioned ratio Wo/Wi exceeds 3.0, the air column resonance sound generated by the shoulder longitudinal groove 3 is likely to be discharged to the ground edge Te side, thereby deteriorating the noise performance. The rigidity of 9 makes the anti-uniform wear performance worse. From this point of view, the ratio Wo/Wi is more preferably 2.0 or more, and more preferably 2.5 or less.

In addition, among the shoulder lateral grooves 8 , the groove intersecting portion 20 on the one side where the groove wall 8A (upper side in FIG. 2 ) on one side of the shoulder lateral groove 8 intersects the shoulder longitudinal groove 3 is larger than the shoulder lateral groove. The groove wall 8B on the other side of 8 (the lower side in FIG. 2 ) and the groove intersecting portion 21 on the other side of the rubber of the shoulder longitudinal groove 3 are located further inward in the tire axial direction. Such a shoulder lateral groove 8 generates a pressure difference acting on the mud between the groove intersecting portion 20 on one side and the groove intersecting portion 21 on the other side, so the mud in the shoulder longitudinal groove 3 can be smoothly discharged by utilizing the pressure difference. Guided into the shoulder lateral groove 8. Therefore, the earth-discharging property and the shearing force of the tire of the present invention are increased, and the mud road performance is further improved.

In addition, in order to reliably exert the above-mentioned function, it is preferable that the groove intersecting portion 20 on one side is located on the inner groove portion 14 and the groove intersecting portion 21 on the other side is located on the outer groove portion 13 . Such shoulder lateral grooves 8 can smoothly guide the mud in the shoulder longitudinal grooves 3 to the shoulder lateral grooves 8 because the width (not shown) of the shoulder lateral grooves 8 leading to the transition portion 15 increases. Therefore, the earth-discharging property and shearing force are further improved.

In addition, in the shoulder lateral groove 8, it is more preferable that the groove intersection portion 20 on one side is located at the end portion 14t of the transition portion 15 (second transition piece 15B in FIG. 2 ) side of the inner groove portion 14, and The groove intersection portion 21 on the other side is located at an 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 to the entire length of the axially outer bezel 15E of the second transition piece 15B. This suppresses the discharge of the air column resonance sound from the shoulder longitudinal groove 3 and ensures the above-mentioned pressure difference, so that the mud road performance and the noise performance can be improved in a balanced manner.

Particularly preferably, the shoulder lateral grooves 8 are inclined toward the rearward landing side in the tire rotation direction. That is, it is preferable that the groove wall 8A on the one side forms a groove wall on the rear landing side of the shoulder lateral groove 8 in the tire rotation direction, and the groove wall 8B on the other side forms a groove wall on the shoulder lateral groove 8 in the tire rotation direction. First touch the ditch wall on the ground side. Such shoulder lateral grooves 8 contact the ground successively from the inner side to the outer side of the tire axial direction due to the rolling of the tire, so the mud is easy to enter when the ground contact starts, and the mud is easy to discharge when the ground contact ends. That is, since the shoulder lateral groove 8 maintains a large amount of mud in the groove of the shoulder lateral groove 8 from the time of the ground contact start to the time of the ground contact end, it exerts a large shearing force and exerts a large soil discharge property at the end of the ground contact. . Therefore, the tire of the present embodiment further improves the mud road performance.

In addition, in a tire in which the shoulder lateral grooves 8 are inclined toward the rear-landing side in the tire rotation direction, the groove intersecting portion 21 on the other side is closer to the ground-impacting side than the groove intersecting portion 20 on the inner side in the tire axial direction. As shown by arrow A in FIG. 2 , the mud in the shoulder longitudinal groove 3 is smoothly discharged to the side of the shoulder lateral groove 8 along with the rolling of the tire. Therefore, at the time of ground contact, more mud is ensured in the shoulder lateral groove 8, and a larger shearing force is exerted, so that the performance on mud roads is further improved.

Further, as shown in FIG. 3 , the ratio Wr/Wg of the width Wr of the shoulder lateral groove 8 connecting to the transition portion 15 to the groove width Wg of the transition portion 15 is preferably 0.8 to 1.8. If the above-mentioned ratio Wr/Wg is increased, the groove width W3 of the shoulder lateral groove 8 increases, and there is a possibility that the air column resonance sound of the shoulder longitudinal groove 3 cannot be suppressed. Conversely, if the ratio Wr/Wg is reduced, it becomes difficult to discharge mud from the shoulder longitudinal groove 3 to the shoulder lateral groove 8 . From this point of view, the ratio Wr/Wg is more preferably 1.0 or more, and more preferably 1.6 or less. Here, the communication width Wr of the transition portion 15 is defined as the shortest distance between the groove intersection portion 20 on one side and the groove intersection portion 21 on the other side.

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

In addition, the shoulder block 9 is provided with a shoulder lug groove 22 extending in the tire axial direction from the intersection portion 13A of the second transition piece 15B and the outer groove portion 13 to the tire axially outer side. , and does not reach the ground Te but forms a terminal. Such shoulder lugs 22 contribute to improved traction performance.

As mentioned above, although the especially preferable embodiment of this invention was demonstrated in detail, this invention is not limited to embodiment shown in figure, It can deform|transform and implement in various forms.

Example

Pneumatic tires (size: 285/60R18) having the pattern shown in Fig. 1 and specifications based on Table 1 were manufactured, and their respective performances were tested. Among them, the common specifications are as follows.

Ground width TW: 200mm

＜Shoulder Main Groove＞

Groove width W1/ground width TW: 3.1%

Groove depth D1: 10.0mm

The angle θ1 of the transition part relative to the tire axial direction: 45 degrees

Ratio La/Lb of the tire circumferential lengths of the inner groove portion and the outer groove portion: 1.17

＜Central Main Ditch＞

Groove width W2/ground width TW: 4.1%

Groove depth D2: 10.0mm

The angle of the central transition part relative to the tire axis: 40 degrees

＜Shoulder lateral groove＞

Groove depth D3/D1: 90%

＜Middle Outer Lug Groove, First Middle Inner Lug Groove＞

Groove depth 5.0～8.0mm

<Shoulder lugs, second middle inner lugs, center lugs 12>

Groove depth 3.0～5.0mm

The test method is as follows.

＜Noise performance＞

Install the test tires on all the wheels of the vehicle (4600cc, 4WD car made in Japan) under the condition of rim 18×8.5JJ and internal pressure (230kPa), and use the loudspeaker installed next to the driver’s window side ear to collect 60km The vehicle interior noise when driving on a road noise measurement road (rough asphalt road) at a speed of /h, and the sound pressure level at the peak of the air column resonance sound in the narrow band around 240 Hz was measured. The evaluation is represented by an index whose reciprocal of Comparative Example 1 is 100, and the larger the numerical value, the better.

＜Dirt road performance＞

In the above-mentioned vehicle installation state, a driver drove the car on a soft dirt track, and comprehensively evaluated the braking force, cornering performance, etc. based on the driver's induction. The evaluation is expressed by comparing 1 to 100, and the larger the value, the better.

＜Traction performance＞

A professional test driver was driven on the same test route under the above-mentioned vehicle conditions, and the degree of transmission of driving force to the road surface according to the driver's feeling was represented by a score of 100 in Comparative Example 1. The higher the value, the better.

＜Uneven wear resistance＞

Using the above-mentioned vehicle, the vehicle was driven for 30 km on a dry asphalt tire test track through limit driving, and the presence or absence of stripe pattern or pattern block defects, uneven wear, etc. was observed with the naked eye. The evaluation is represented by a score of 100 for Comparative Example 1, and the larger the numerical value, the better the uneven wear resistance.

The results of the tests are shown in Table 1.

Table 1

As a result of the test, it was confirmed that various performances of the tires of the examples were improved compared with those of the comparative examples.

Claims (7)

1. A pneumatic tire, wherein the tread portion is provided with: a shoulder longitudinal groove extending along the tire circumferential direction on the side closest to the ground contact end, and a shoulder transverse groove extending from the above shoulder longitudinal groove across the ground contact end, Accordingly, a shoulder block row in which shoulder blocks are arranged at intervals in the tire circumferential direction is formed on the tread portion, and this pneumatic tire is characterized in that The shoulder longitudinal grooves form trapezoidal wavy serrations including an outer groove portion, an inner groove portion, and a transition portion, the outer groove portion extends axially outward in the tire circumferential direction, and the inner groove portion is located closer to the outer groove portion than the outer groove portion. The tire axially inner side extends along the tire circumferential direction, and the transition portion extends obliquely from the inner groove portion to the outer groove portion, and extends obliquely to one side with respect to the tire axial direction from the inner groove portion to the outer groove portion. a first transition piece, and a second transition piece extending obliquely in a direction opposite to the first transition piece, The shoulder lateral groove is inclined to one side with respect to the tire axial direction, and the straight line connecting the intersection point P1 where the groove centerline intersects the shoulder longitudinal groove and the intersection point P2 where the groove centerline and the ground contact edge intersect is opposite to the tire The axial angle is 5 to 20 degrees, and The shoulder lateral groove extends linearly from the shoulder longitudinal groove to the ground contact end, and the groove width gradually increases toward the outside in the tire axial direction, and the groove width Wo of the shoulder lateral groove at the ground contact end and the above The ratio Wo/Wi of the groove width Wi at the connecting portion between the shoulder lateral groove and the shoulder longitudinal groove is 1.5 to 3.0, and Among the above-mentioned shoulder lateral grooves, the groove intersecting portion on one side where the groove wall on one side of the shoulder lateral groove intersects with the above-mentioned shoulder longitudinal groove is located more than the groove wall on the other side of the shoulder lateral groove intersects with the above-mentioned tire. The groove intersection on the other side where the shoulder longitudinal grooves intersect is closer to the inner side of the tire axial direction, The shoulder lateral groove is connected to the entire length of the axially outer bezel of the second transition piece. 2. The pneumatic tire according to claim 1, wherein: The groove intersecting portion on the one side is located on the inner groove portion, and the groove intersecting portion on the other side is located on the outer groove portion. 3. The pneumatic tire according to claim 2, wherein: The groove intersecting portion on the one side is located at an end portion of the inner groove portion on the transition portion side, and the groove intersecting portion on the other side is located at an end portion of the outer groove portion on the transition portion side. 4. The pneumatic tire according to claim 3, wherein: A ratio Wr/Wg of a width Wr connecting the shoulder lateral groove to the transition portion to a groove width Wg of the transition portion Wr/Wg is 0.8 to 1.8. 5. The pneumatic tire according to any one of claims 1 to 4, characterized in that, In the shoulder longitudinal groove, the axial distance, that is, the projection amount Ld, from the axially outer bezel of the inner groove portion to the axially outer bezel of the outer groove portion, is the outer groove portion 0.4 to 0.8 times the axial width Lo of the tire. 6. The pneumatic tire according to any one of claims 1 to 4, characterized in that, The shoulder block rows are formed substantially point-symmetrically with respect to any point on the tire equator except for a variable pitch. 7. The pneumatic tire according to any one of claims 1 to 4, characterized in that, The above-mentioned shoulder lateral grooves are inclined toward the rear landing side in the direction of tire rotation, The groove wall on the one side is a groove wall on the rear landing side in the tire rotation direction of the shoulder lateral groove, The groove wall on the other side is a groove wall on the ground-first side of the shoulder lateral groove in the tire rotation direction.