KR101787770B1 - Pneumatic tire - Google Patents

Abstract

The present invention provides a pneumatic tire improved in wet performance while suppressing deterioration of steering stability performance and anti-abrasion performance.
In the pneumatic tire of the present invention, the ground contact surface of the tread portion 2 is a tire whose ground contact length in the tire circumferential direction on the tire equator C is 1.05 times to 1.15 times the ground contact length at the shoulder position . The land portion width Wc of the center land portion 5 in the tire axial direction is 0.8 times or more and less than 1.0 times the land portion width Ws of the shoulder land portion 6 in the tire axial direction. The center land portion 5 continuously extends in the tire circumferential direction in the region inside the tire axial direction from the intermediate position of the land portion width Wc and has an average groove depth of the center main groove 3 and the shoulder main groove 4 And a center transverse groove (8) connecting the center main groove (3) and the shoulder main groove (4) and having a groove depth smaller than the average groove depth is provided. The shoulder land portion 6 is a rib which is continuous without interruption in the tire circumferential direction.

Description

Pneumatic tire {PNEUMATIC TIRE}

The present invention relates to a pneumatic tire having improved wet performance while suppressing deterioration of steering stability performance and anti-abrasion performance, and particularly to a pneumatic tire suitable for a small truck.

A pneumatic tire having a block pattern in which a plurality of blocks are formed in a tread portion is known. In recent years, there is a demand for further improvement of the wet performance for such pneumatic tires. For the purpose of smoothly draining the water film between the tread portion and the road surface in order to improve the wet performance, for example, a groove width of the main groove or the transverse groove provided in the tread portion has been proposed.

However, in the above-described method, there is a problem that the stiffness of the pattern is lowered and the steering stability performance and the anti-abrasion performance are deteriorated by reducing the ground area.

Japanese Patent Application Laid-Open No. 2002-46427

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-described problems, and it is an object of the present invention to provide a golf club head which is characterized in that the arrangement positions of the main grooves extending in the tire circumferential direction, the groove depths of the groove and the transverse groove, And to provide a pneumatic tire having improved wet performance while suppressing deterioration of steering stability performance and anti-abrasion performance.

According to a first aspect of the present invention, there is provided a tire according to the first aspect of the present invention, wherein a tread portion is provided with a center main groove continuously extending in the tire circumferential direction on the tire equatorial plane and a pair of continuously extending tire circumferential portions A pair of center land portions extending between the shoulder groove and the center main groove by a shoulder groove and a pair of shoulder land portions extending between the shoulder groove and the tread edge, The ground surface of the tread portion has a ground contact length in the circumferential direction of the tire on the tire equator in a normal load load state in which the ground contact is grounded at a camber angle of 0 degrees while the normal load is applied, 1.05 to 1 of the grounding length in the tire circumferential direction at the shoulder position with a distance of 40% of the grounding width And the center land portion has a land portion width in the tire axial direction of the center land portion being 0.8 times or more and less than 1.0 times the width of the land portion in the tire axial direction of the shoulder land portion, And a groove depth continuously extending in the tire circumferential direction in a region inside the tire axial direction from the intermediate position of the width of the land portion and having a groove depth of 0.2 to 0.5 times the groove depth of the center main groove and the groove depth of the shoulder main groove And a center transverse groove connecting the center main groove and the shoulder main groove and having a groove depth of 0.2 to 0.5 times the average groove depth is provided on the outer peripheral surface of the shoulder land portion, And a pneumatic tire.

According to a second aspect of the present invention, the center land portion includes an inner block on the inner side in the tire axial direction of the center sub-groove and an outer block on the outer side in the tire axial direction, and a block width in the tire axial direction of the inner block, Is 0.6 to 0.9 times the block width of the block.

According to a third aspect of the present invention, the inner block is provided with a semi-open type inner sipe extending outward from the center main groove in the tire axial direction, and the outer block is provided with a semi open And the total number of the inner sipes is smaller than the total number of the outer sipes.

According to a fourth aspect of the present invention, the inner block has a substantially parallelogram shape due to the angle of the center transverse groove with respect to the tire circumferential direction being 45 to 75 degrees, and the outer block has a plurality of Wherein the outer block piece includes a first outer piece including an acute corner portion on the outer side in the tire axial direction of the outer block and a second outer piece including a corner portion at an obtuse angle outer side in the tire axial direction of the outer block, And the minimum length La of the second outer piece in the tire circumferential direction is shorter than the minimum length Lb of the first outer piece in the tire circumferential direction .

According to a fifth aspect of the present invention, the inner block is divided into a plurality of inner block pieces by the inner sipes, and the inner block pieces include a first portion including an acute corner portion inside the tire axial direction of the inner block, And a second inner piece including an inner piece and an obtuse corner portion inside the tire axial direction of the inner block, wherein a minimum width Wa in the tire axial direction of the second inner piece is larger than a minimum width Wa of the first inner piece Is smaller than a minimum width (Wb) in the axial direction of the tire.

The pneumatic tire of the present invention is characterized in that the tread portion has a center main groove continuously extending in the tire circumferential direction on the tire equatorial plane and a pair of shoulder main grooves continuously extending in the tire circumferential direction on both outer sides of the center main groove in the tire axial direction A pair of center land portions extending between the shoulder groove and the center main groove and a pair of shoulder land portions extending between the shoulder groove and the tread grounding end.

The ground surface of the tread portion on the tire equatorial surface in the circumferential direction of the tire on the tire equatorial plane is set to be equal to or less than the ground contact length on the tire equatorial plane in the normal load load condition in which the tire is rimmed in the normal rim, And 1.05 to 1.15 times the grounding length in the tire circumferential direction at the shoulder position at a distance of 40% of the tread ground width from the tire equator. Such a pneumatic tire can reduce the difference between the ground pressure on both sides in the tire axial direction in the center land portion and the difference in the grounding pressure between the center land portion and the shoulder land portion. Therefore, the pneumatic tire of the present invention can suppress the uneven wear such as the shoulder drop wear which is likely to occur in the shoulder land portion, and the anti-abrasion performance is further improved.

The width of the land portion in the tire axial direction of the center land portion is set to be not less than 0.8 times and not more than 1.0 times the width of the land portion in the tire axial direction of the shoulder land portion. As a result, the rigidity of the shoulder land portion where a large lateral force acts at the time of turning travel can be enhanced, and the steering stability performance and the anti-abrasion performance can be improved.

The center land portion is provided with a center land portion extending continuously in the tire circumferential direction in a region inside the tire axial direction from an intermediate position of the width of the land portion of the center land portion and having a groove depth of the center main groove and an average groove depth of the groove depth of the shoulder main groove And a center transverse groove connecting the center main groove and the shoulder main groove and having a groove depth of 0.2 to 0.5 times the average groove depth is provided. This center sub-groove drains the water film between the center land portion and the road surface more reliably. In addition, the center transverse groove facilitates the discharge of the water in the center main groove or the center sub groove to the shoulder main groove side easily. In addition, the center sub-grooves and the center transverse grooves are defined such that the groove depth is as small as 0.2 to 0.5 times the average depth. Therefore, the pneumatic tire of the present invention can prevent the lowering of the rigidity of the center land portion, and further improve the wet performance while securing the steering stability performance and the anti-abrasion performance at a high level.

In addition, the shoulder land portion is a rib which is continuous without being interrupted in the tire circumferential direction. As a result, the rigidity of the shoulder land portion can be further increased, and it is possible to cope with a large change in the grounding pressure in the vicinity of the tread ground end, and the steering stability performance and the anti-abrasion performance can be further secured.

1 is an exploded view of a tread portion showing a pneumatic tire according to an embodiment of the present invention.
Fig. 2 (a) is a plan view showing the ground surface of the pneumatic tire according to the embodiment of the present invention grounded on the road surface, and Fig. 2 (b) is a sectional view parallel to the tire equatorial plane showing the state of Fig.
3 is a partial enlarged view of Fig.

As shown in Fig. 1, the pneumatic tire (hereinafter, simply referred to as "tire") of the present embodiment is suitably used as a tire for a small truck, A pair of shoulder grooves 4 extending continuously in the tire circumferential direction are provided on both sides of the center main groove 3 in the tire axial direction do. The tread portion 2 is provided with a pair of center land portions 5 extending between the center main groove 3 and the shoulder main groove 4 and a pair of center land portions 5 extending between the shoulder main groove 4 and the tread ground Te A pair of extending shoulder land portions 6 are distinguished. Therefore, the tire of the present embodiment has four land portions in total in the tread portion 2.

Here, the "tread grounding end" Te is a tire grounding end (Te) which is rim mounted on a regular rim and filled with a normal internal pressure, Is set as the ground position on the outermost side in the tire axial direction. The distance in the tire axial direction between the tread ground ends Te and Te is determined as the tread ground contact width TW. The dimensions of each part of the tire and the like are set to values in the normal state unless otherwise specified.

In the standard system including the tire-based standard, the above-mentioned "normal rim" is a rim defined by the standard for each tire, for example, "standard rim" if JATMA, "design rim" Measuring Rim ".

The "normal internal pressure" refers to the air pressure prescribed for each tire in a standard system including a tire-based standard, "maximum air pressure" for JATMA, "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES "and" INFLATION PRESSURE "for ETRTO, and 180 kPa for tires for passenger cars.

The term "normal load" refers to the load specified by each standard for each tire in the standard system including the tire-based standard, "maximum load capacity" for JATMA, "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES "and" LOAD CAPACITY "in case of ETRTO. In the case of a tire for a passenger car, the load corresponds to 88% of the load.

In the present embodiment, the center main groove 3 has a linear portion 3A having a constant groove width of the center main groove 3 in the tire circumferential direction and an enlarged portion 3A having a larger groove width than the straight portion 3A 3B are alternately formed. The center main groove 3 is capable of suppressing unstable behavior such as wobbling or leaning of the vehicle at the same time in the linear portion 3A and discharging drainage in the linear portion 3A smoothly. In addition, the swollen portion 3B can effectively collect the water film on the road surface. Therefore, the center main groove 3 can improve the steering stability performance and the wet performance.

The shoulder main groove 4 is linear along the tire circumferential direction, and is formed to have a constant width in the present embodiment. The shoulder main groove 4 of the present embodiment is formed wider than the center main groove 3. This shoulder groove 4 helps to improve steering stability performance and wet performance.

W1 and W2 and groove depths (not shown) of the center main groove 3 and the shoulder main groove 4 (groove widths perpendicular to the longitudinal direction of the grooves, Can be variously set according to custom. However, if the groove widths W1 and W2 and / or groove depths are excessively large, the rigidity of each of the land portions 5 and 6 is lowered, and steering stability performance and anti-abrasion performance tend to deteriorate. Conversely, Smaller size tends to deteriorate drainage. Therefore, the groove widths W1 and W2 are preferably 2.5% to 8.0% of the tread width TW, for example, and the groove depth is preferably 8.0 mm to 15.0 mm.

The arrangement position of the shoulder main groove 4 is set such that the tire axial distance L1 between the center line G2 and the tire equator C is preferably 13% or more of the tread ground width TW, , More preferably not less than 20%, preferably not more than 26%, more preferably not more than 25%. By setting the shoulder main groove 4 in this range, the rigidity balance of each of the center land portion 5 and the shoulder land portion 6 is improved and the steering stability performance is improved.

The ground surface Se of the tread portion 2 in the normal load load condition (in this drawing, the ground surface Sb of the tread portion 2 in the normal load application state, as shown in Fig. 2 (a) The grounding length Lc in the circumferential direction of the tire on the tire equator C is greater than the shoulder position (the area surrounded by the edge YY) at a distance of 40% of the treading width TW from the tire equator C Sh is set to 1.05 times to 1.15 times the grounding length Ls in the tire circumferential direction. That is, in the present invention, the ratio of the ground surface (Se) to the ground surface of the conventional tire is set to be small (Lc / Ls), and thus is close to a substantially rectangular shape. These tires have a smaller difference in ground pressure on both sides in the axial direction of the tire in the center land portion 5 and a difference in contact pressure between the center land portion 5 and the shoulder land portion 6, The shoulder drop wear which is easy to occur can be suppressed, and furthermore, the anti-abrasion performance is improved. In the present embodiment, since the center main groove 3 is provided on the tire equator C, the grounding length Lc is set to be smaller than the virtual grounding edge (i.e., Y1).

Here, if the ratio (Lc / Ls) of the grounding length Lc on the tire equator C to the grounding length Ls on the shoulder position Sh is less than 1.05, the shoulder land 6, The straight pressure stability is deteriorated, and the wear energy of the shoulder land portion 6 becomes large, so that the shoulder wear tends to occur. In contrast, when the ratio Lc / Ls is larger than 1.15, the contact pressure of the shoulder land portion 6 becomes excessively small as compared with the center land portion 5, dragging occurs in the shoulder land portion 6, Wear is likely to occur. From this viewpoint, the ratio (Lc / Ls) is preferably 1.07 or more, and more preferably 1.13 or less.

1, the center land portion 5 is formed so that the land portion width Wc of the center land portion 5 in the tire axial direction is smaller than the width Wc of the land portion in the tire axial direction of the shoulder land portion 6. [ Is set to be 0.8 times or more and less than 1.0 times the land portion width (Ws). The center land portion 5 and the shoulder land portion 6 are secured in a balanced manner in the rigidity of each of the land portions 5 and 6, thereby enhancing steering stability performance and anti-abrasion performance. On the other hand, when the land portion widths Wc and Ws of the land portions 5 and 6 are not constant widths, the maximum width is defined as the width of each land portion.

The center land portion 5 has a center portion groove 7 continuously extending in the tire circumferential direction in an area inside the tire axial direction from an intermediate position of the land portion width Wc of the center land portion 5, And a center transverse groove (8) connecting the center main groove (3) and the shoulder main groove (4). Accordingly, the center land portion 5 has an inner block row 10R in which the inner block 10 divided in the tire axial direction inner side than the center outer groove 7 is arranged in the tire circumferential direction, The outer blocks 11 divided in the tire axial direction outer side are divided into the outer block rows 11R provided side by side in the tire circumferential direction.

The center grooves 7 of the present embodiment extend linearly along the tire circumferential direction. The center grooves 7 can effectively drain the water film between the center land portion 5 and the road surface.

The center transverse groove (8) extends obliquely with respect to the tire axial direction. In the pair of center land portions 5 and 5, the inclination of the center transverse groove 8 may be the same or opposite. In the present embodiment, the center land portion 5 is provided with the center transverse grooves 8 which are inclined in the same direction (right upward in this example). This center transverse groove 8 can smoothly discharge the water in the center main groove 3 into the shoulder groove 4 by using the centrifugal force at the time of turning regardless of the direction of rotation of the tire.

The angle? 1 of the center transverse groove 8 with respect to the tire circumferential direction is preferably 45 degrees or more, more preferably 50 degrees or more, further preferably 75 degrees or less, and more preferably 65 degrees or less. When the angle [theta] 1 is large, there is a possibility that the drainability at the time of straight running is deteriorated. On the contrary, when the angle [theta] 1 is small, there is a fear that the rigidity of the center land portion 5 is lowered. On the other hand, in the present invention, since the grounding pressure in the center land portion 5 is made uniform, the angle? 1 of the center transverse groove 8 can be made small.

3, the center transverse groove 8 of the present embodiment is provided with a constant width portion 12 formed at a central portion of the center transverse groove 8 and having a constant groove width, A first wider portion 13 connecting the width portion 12 and the center main groove 3 and having a groove width larger on the side of the center main groove 3 and a second wider portion 13 connecting the equal width portion 12 and the shoulder main groove 4, And a second widened portion 14 which is larger on the shoulder main groove 4 side. This center transverse groove 8 helps smooth drainage between the center main groove 3 and the shoulder main groove 4 and helps improve the wet performance.

The groove width ratio W4a / W4 of the groove width W4a of the first wider portion 13 and the groove width W4 of the equal width portion 12 is preferably 1.1 or more, Preferably 1.3 or more. Similarly, the groove width ratio W4b / W4 of the groove width W4b of the second wider portion 14 and the groove width W4 of the equal width portion 12 is preferably 1.5 or more, more preferably 2.0 or more to be. On the other hand, if the groove width ratios W4a / W4 and W4b / W4 are large, the rigidity of the inner block 10 and / or the outer block 11 may be reduced. From this viewpoint, the groove width ratio W4a / W4 is preferably 2.1 or less, more preferably 1.9 or less. The groove width ratio W4b / W4 is preferably 4.5 or less, and more preferably 4.0 or less. It is preferable that the groove width W4b of the second widened portion 14 is larger than the groove width W4a of the first widened portion 13 in order to smoothly drain the wedge end Te.

The groove depth D3 (not shown) of the center groove 7 and the groove depth D4 (not shown) of the center transverse groove 8 are both equal to the groove depth of the center groove 3 and the shoulder groove 4 ) Of the groove depth (DA) (not shown) of the groove depth of the groove (not shown). The center grooves 7 and the center transverse grooves 8 can smoothly discharge the water film between the center land portion 5 and the road surface while preventing the rigidity of the center land portion 5 from deteriorating. On the other hand, if the groove depth D3 of the center groove 7 and the groove depth D4 of the center transverse groove 8 are less than 0.2 times the average groove depth DA, improvement in wet performance can not be expected, When the depths D3 and D4 exceed 0.5 times the average groove depth DA, the rigidity of the center land portion 5 is lowered and the steering stability performance and the anti-abrasion performance are deteriorated. In particular, the groove depths D3 and D4 are more preferably 0.3 times or more, and more preferably 0.4 times or less, the average groove depth DA.

The groove width W3 of the center groove 7 is preferably at least 15%, more preferably at least 20% of the groove width W2 of the shoulder groove 4, Or more, preferably 45% or less, and more preferably 40% or less. Similarly, the minimum groove width (groove width of the equal width portion 12 in the present example) of the center transverse groove 8 is preferably 1.0 mm or more, more preferably 2.0 mm or more, and preferably 5.0 mm or more Mm or less, more preferably 3.5 mm or less.

The block width W6 in the tire axial direction of the outer block 11 is larger than the block width W5 of the inner block 10. [ Accordingly, the lateral stiffness of the outer block 11, which is subjected to a large lateral force at the time of turning, is increased, and the anti-abrasion performance and the steering stability performance can be improved. On the other hand, if the block width W6 of the outer block 11 is excessively increased, the lateral stiffness of the inner block 10 is excessively lowered, which may deteriorate steering stability performance and inner abrasion performance of this portion . Therefore, the block width W5 of the inner block 10 is preferably at least 0.6 times, more preferably at least 0.7 times, and preferably at least 0.9 times the block width W6 of the outer block 11 , And more preferably 0.8 times or less.

The inner block 10 of the present embodiment is provided with a semi-open type inner sip 15 extending outward from the center main groove 3 in the axial direction of the tire and having an outer end terminated in the inner block 10. Accordingly, the inner block 10 is divided into a plurality of inner block pieces 10a by the inner side sip 15. As shown in Fig. The inner block piece 10a of the present embodiment has a first inner piece 10a1 including an acute corner portion Ku1 on the inner side in the tire axial direction of the inner block 10, And a second inner piece 10a2 including a corner Ku2 at an obtuse angle inside the direction.

The outer block 11 is provided with a semi-open type outer sipe 16 extending inward from the shoulder groove 4 in the axial direction of the tire and having its inner end terminated in the outer block 11. Accordingly, the outer block 11 is divided into a plurality of outer block pieces 11a by the outer sip 16. The outer block piece 11a has a first outer piece 11a1 including an acute corner portion Ks1 on the outer side in the tire axial direction of the outer block 11, And a second outer piece 11a2 including a corner portion Ks2 of an obtuse angle outward in the axial direction.

The inner siphon 15 and the outer siphon 16 relax the deformation of the center land portion 5 without excessively lowering the rigidity thereof to suppress the heel and toe wear of the blocks 10 and 11, Edge effect, and enhances traction on a wet road surface.

It is preferable that the total number of inner siphs 15 is smaller than the total number of the outer siphs 16. Accordingly, it is possible to apply a large amount of edge component to the outer block 11, which is largely affected by the lateral force at the time of turning, while suppressing the decrease in rigidity of the inner block 10 having a large grounding pressure at the time of straight running. This also makes it possible to equalize the grounding pressure of the outer block 11 having a large block width in the axial direction of the tire and to alleviate deformation.

It is also preferable that both the inner siphon 15 and the outer siphon 16 extend in the same direction as the center transverse groove 8 and the angle of the sipes 15, Is preferably formed at the same angle as the angle [theta] 1. These sipes 15 and 16 help to secure a high rigidity of the block pieces 10a and 11a separated from the inner block 10 and the outer block 11. [

The tire axial length L5 of the inner side siph 15 is preferably 65% or more and 85% or less of the block width W5 of the inner block 10 in order to further improve the above-described action. Likewise, the tire axial length L6 of the outer sipe 16 is expressed by the following equation. Preferably 65% or more and 85% or less of the block width W6 of the outer block 11.

In the present embodiment, the minimum length La of the second outer piece 11a2 in the tire circumferential direction is smaller than the minimum length Lb of the first outer piece 11a1 in the tire circumferential direction. That is, the minimum length Lb of the first outside piece 11a1 including the corner portion Ks1 of the acute angle of the block in which the rigidity is liable to be reduced is set to be the corner portion Ks2 of the obtuse- The stiffness balance of each of the outer pieces 11a1 and 11a2 can be ensured and the uneven wear and the like likely to occur in the outer block 11 can be suppressed by making the length of the outer piece 11a2 larger than the minimum length La of the second outer piece 11a2 . On the other hand, if the minimum length La is excessively smaller than the minimum length Lb, the rigidity balance of the respective outer pieces 11a1 and 11a2 may be lowered and the anti-abrasion performance may deteriorate. The ratio La / Lb of the minimum length La of the second outer piece 11a2 to the minimum length Lb of the first outer piece 11a1 is preferably not less than 0.65, 0.75 or more, preferably 0.95 or less, and more preferably 0.85 or less.

In the present embodiment, the minimum width Wa in the tire axial direction of the second inner piece 10a2 is formed to be smaller than the minimum width Wb of the first inner piece 10a1 in the tire axial direction. That is, the minimum width Wb of the first inner piece 10a1 including the acute corner portion Ku1 of the block in which the rigidity is likely to be lowered is set to be the corner portion Ku2 of the obtuse- Is made larger than the minimum width (Wa) of the second inner piece (10a2) including the inner side piece (10a1), the rigidity balance of the inner side pieces (10a1 and 10a2) is ensured to improve the steering stability performance. On the other hand, if the minimum width Wa is excessively smaller than the minimum width Wb, the stiffness balance of the inner side pieces 10a1 and 10a2 may be lowered and the anti-abrasion performance may deteriorate. Therefore, the ratio Wa / Wb of the minimum width Wa of the second inner piece 10a2 to the minimum width Wb of the first inner piece 10a1 is preferably not less than 0.85, 0.87 or more, preferably 0.95 or less, and more preferably 0.93 or less.

In addition, the shoulder land portion 6 is a rib which is continuous without being interrupted in the tire circumferential direction. As a result, the rigidity of the shoulder land portion 6 becomes higher, and the steering stability performance and the anti-abrasion performance are further improved. In addition, the effect of suppressing the uneven wear in the vicinity of the tread grounding end Te, where the change in the grounding pressure increases, is large.

A shoulder inner lug groove 20 extending in the tire axial direction outside from the shoulder main groove 4 in a short length and terminating in the shoulder land portion 6 is provided on the tire equator C side of the shoulder land portion 6 of the present embodiment, And a shoulder inner side sifter 21 having a shorter length in the axial direction of the tire than the shoulder inner side lug grooves 20 are provided. The shoulder inner lug grooves and the shoulder inner siphons mitigate the deformation of the ribs and help to reduce wear and tear on the lateral edges of the ribs. A shoulder outer lug groove 22 extending in the tire axial direction from the tread ground end Te to a short length and terminating in the shoulder land portion 6 is provided on the tread ground end Te side of the shoulder land portion 6, And a shoulder outer sip 23 having a shorter length in the axial direction of the tire than the shoulder outer lug groove 22 is provided.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Example

A pneumatic tire for a small truck (size: 205 / 85R15) having the pattern of Fig. 1 and based on the specifications of Table 1 was manufactured and tested for each performance of these pneumatic tires. On the other hand, common specifications are as follows.

Tread ground width (TW): 150 mm

Rim size: 15 × 5.5J

<Center Home>

Groove width (W1) / Tread ground width (TW): 5.1%

Groove depth: 10.1 mm

<Shoulder strap>

Groove width (W2) / Tread ground width (TW): 6.5%

Groove depth: 10.1 mm

<Center Support>

Groove width (W3) / Tread ground width (TW): 1.8%

<Center transverse groove>

Groove width (W4): 2.2 mm

Groove depth (D4): 2.3 mm

<Inner side>

Width: 6.0 mm to 9.0 mm

Siphon depth: 8.5 mm

<Outside Saif>

Width: 6.0 mm to 9.0 mm

Siphon depth: 6.0 mm

Other

<Each shoulder lug groove>

Depth of groove: 7.7 mm

<Each shoulder Saif>

Width: 2.0 mm to 5.0 mm

Saif depth: 5.0 mm to 10.0 mm

<Steering stability performance>

Four test wheels were mounted on a Japanese small truck with the following specifications, and a test driver on a dry asphalt road was driven by a driver for a ride to obtain steering stability, steering stability, grip stability, etc. Were evaluated by the sensory evaluation of the driver. The result is indicated by the index of Comparative Example 1 being 100. The larger the value, the better.

Displacement: 3000 ㎤

Withstand pressure: 600 ㎪

Load capacity: 1t

&Lt; Lateral hydroplaning test >

As the test vehicle, the vehicle was entered on the asphalt road surface having a radius of 100 m and the puddle with a depth of 10 mm and a length of 20 m was installed on the course, the speed was gradually increased, and the lateral acceleration (lateral G) The average lateral acceleration G of the front wheel at a speed of 80 km / h to 80 km / h was calculated. The result is indicated by an index of 100 for Comparative Example 1. The larger the number, the better.

&Lt; My lapping performance >

The difference in wear amount at the both groove edges in the tire axial direction of the shoulder main groove after running was measured under the same vehicle condition as above. Specifically, each construction tire was mounted on four wheels, the dry asphalt road surface was run at 15,000 km, five places were measured on the tire circumference, and an average value was calculated. The result is indicated by an index with the reciprocal of Comparative Example 1 as 100. [ The larger the value, the smaller the amount of uneven wear is, and the better.

The test results are shown in Table 1.

As a result of the test, it can be confirmed that the tire of the embodiment has improved various performances as compared with the comparative example.

2: Tread part 3: Center main groove
4: Shoulder groove 5: Center land portion
6: shoulder land portion 7: center sub-groove
8: center transverse groove C: tire equator
Wc: width of the land portion of the center land portion Ws: width of the land portion of the shoulder land portion
Te: Tread grounding stage

Claims (5)

And a pair of shoulder grooves extending continuously in the circumferential direction of the tire at both outer sides of the center axis of the tire in the axial direction of the tire by a pair of shoulder grooves extending continuously in the tire circumferential direction on the tread portion, A pair of center land portions extending between the main grooves and a pair of shoulder land portions extending between the shoulder main groove and the tread ground end,
In a normal load condition, which is mounted on a regular rim and filled with a normal internal pressure and grounded on a camber angle 0-degree plane by applying a normal load,
The ground plane of the tread portion is 1.05 to 1.15 times the ground contact length in the tire circumferential direction at the shoulder position at a distance of 40% of the tread ground width from the tire equator,
Wherein the center land portion has a land portion width in the tire axial direction of the center land portion being 0.8 times or more and less than 1.0 times the width of the land portion in the tire axial direction of the shoulder land portion,
The center land portion is provided with a center land portion extending continuously in the tire circumferential direction in an area inside the tire axial direction from an intermediate position of the width of the land portion and extending from the groove depth of the center main groove to the groove depth of the shoulder main groove, A center transverse groove connecting the center main groove and the shoulder main groove and having a groove depth of 0.2 to 0.5 times the average groove depth,
Wherein the center land portion includes an inner block on the inner side in the tire axial direction of the center sub-groove and an outer block on the outer side in the tire axial direction,
Wherein the inner block is provided with a semi-open type inner sipe extending from the center main groove to an outer side in the tire axial direction,
The outer block is provided with a semi-open type outer sipe extending inward from the shoulder groove in the tire axial direction,
Wherein the total number of the inner sipes is smaller than the total number of the outer sipes,
Wherein the shoulder land portion is a rib which is continuous without being interrupted in the tire circumferential direction. The pneumatic tire according to claim 1, wherein the block width of the inner block in the tire axial direction is 0.6 to 0.9 times the block width of the outer block. The tire according to claim 1 or 2, wherein the inner block has a parallelogram shape due to the angle of the center transverse groove with respect to the tire circumferential direction being 45 to 75 degrees,
Wherein the outer block is divided into a plurality of outer block pieces by the outer sipes,
Wherein the outer block piece includes a first outer piece including an acute corner portion on the outer side in the tire axial direction of the outer block and a second outer piece including an obtuse corner portion on the tire axial outer side of the outer block,
The minimum length La of the second outer piece in the tire circumferential direction is shorter than the minimum length Lb of the first outer piece in the tire circumferential direction. 3. The image forming apparatus according to claim 1 or 2, wherein the inner block is divided into a plurality of inner block pieces by the inner sipes,
Wherein the inner block piece includes a first inner piece including an acute angle corner inside the tire axial direction of the inner block and a second inner piece including an obtuse angle corner inside the tire axial direction of the inner block,
Wherein a minimum width Wa in the tire axial direction of the second inner piece is smaller than a minimum width Wb in the tire axial direction of the first inner piece. The apparatus according to claim 1 or 2, wherein the center transverse groove has a first width portion connecting the equal width portion and the center main groove and having a groove width larger toward the center main groove side, And a second widened portion connecting the shoulder groove and having a groove width enlarged toward the shoulder groove side.

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