JP3913045B2 - Pneumatic tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that reduces outside noise generated when the tire travels while preventing occurrence of uneven wear.
[0002]
[Prior art]
As the noise regulations become stricter, it is required to further reduce the outside noise generated when the tires are traveling. It is said that the noise caused by the block pattern is particularly large as the outside noise generated by the tire. The pattern noise due to the block pattern is noise generated mainly by an impact force in which blocks arranged in the tire circumferential direction are successively hit against the road surface. Conventionally, as a method of reducing the pattern noise, the noise is reduced by changing the pitch of the blocks arranged in the tire circumferential direction and dispersing the impact sound generated by each block to generate white noise. there were.
[0003]
However, although the method using white noise reduces noise as a sense of sound, it has not been sufficient to reduce the absolute value of noise.
[0004]
In addition, tires with the above block pattern are prone to heel and toe wear with different wear amounts on the stepping side and the kicking side with respect to the tire circumferential direction due to shear deformation when each block repeatedly touches and separates from the road surface. Become. Further, when the contact pressure uniformity of the block is reduced due to heel and toe wear, polygonal wear tends to occur. Such uneven wear causes a reduction in braking / driving performance.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire that reduces the absolute value of outside noise generated when the tire travels while preventing the occurrence of uneven wear.
[0006]
[Means for Solving the Problems]
The pneumatic tire of the present invention that achieves the above object is provided with three main grooves extending linearly in the tire circumferential direction on the tread surface, and the main grooves are spaced apart by a plurality of sub-grooves in the tire circumferential direction. In a pneumatic tire in which a block row is formed by communicating , both outer sides of the three main grooves are formed as ribs, the sub grooves are inclined obliquely with respect to the tire circumferential direction, and the sub grooves 5-30% of a groove area ratio to the total groove area, 1 the sipes to 8-16 present the number of the sub-grooves distributed in a ground area, extending in the tire width direction in each block forming the block row Four are provided.
[0007]
In another pneumatic tire of the present invention, three main grooves extending linearly in the tire circumferential direction are provided on the tread surface, and the main grooves are communicated with each other with a plurality of sub grooves spaced in the tire circumferential direction. In the pneumatic tire in which the block row is formed and the outer sides of the three main grooves are ribs, the sub grooves are inclined obliquely with respect to the tire circumferential direction and occupy the entire groove area of the sub grooves. the groove area ratio 5-30%, to 8 to 16 present the number of the sub-grooves distributed in a ground area, a plurality of lug grooves at intervals in the tire circumferential direction in the outer grounding region on the rib The number of the lug grooves is 0.6 to 1.4 times the number of the sub-grooves .
[0008]
As described above, in any tire, in the tire in which a block row partitioned by the sub grooves is formed between the three main grooves extending linearly in the tire circumferential direction, the tire occupies the entire groove area of the sub grooves. Because the groove area ratio and the number of sub-grooves distributed in the ground contact area are in a specific range, when the tire is grounded and the tread surface is deformed, the block is deformed so that the sub-groove is blocked. Since the sliding of the block with respect to the road surface is suppressed and the generation of the air pumping sound due to the sub-groove space can be suppressed together with the ground frictional vibration vibration sound, the absolute value of the noise is reduced.
[0009]
Furthermore, in the former tire, by providing sipes in each block of the block row, the shearing force acting on the moving direction side of the blocks during braking / driving is dispersed and absorbed by the sipes, thus preventing heel and toe wear. it can.
[0010]
In the latter tire, by providing a lug groove outside the ground contact area of the rib, the stress applied to the outer portion in the tire width direction when the tire touches is absorbed by deformation of the lug groove, and the pressure distribution in the ground contact area is made uniform. Polygonal wear can be prevented.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the sub-groove means a groove having a smaller groove width than the main groove, while the sipe means a kerf having a smaller groove width. The groove width is about 0.5 to 2.0 mm.
[0012]
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0013]
FIG. 1 is a development view illustrating a tread surface of a pneumatic tire according to the present invention.
[0014]
In FIG. 1, the tread surface is provided with three main grooves 1 extending linearly in the tire circumferential direction, and a plurality of sub-grooves 2 communicate with each other at intervals in the tire circumferential direction. A block 3 is formed. That is, two rows of block rows 4 extending in the tire circumferential direction are formed in the center portion in the tire width direction, and ribs 5 are formed on the outer sides of the main grooves 1 on both outer sides.
[0015]
In the two block rows 4, the arrangement pitch of the blocks 3 is changed, and the pattern noise is converted to white noise. The sub-groove 2 is inclined with respect to the tire circumferential direction so as to reduce the impact force when the block 3 collides with the road surface.
[0016]
Each block 3 is provided with two parallel sipes 6 extending in the tire width direction, and each of the blocks 3 has one end opened to the main groove or the sub-groove. Moreover, the two single-side open sipes 6 have their open ends opposite to each other in the tire width direction.
[0017]
Furthermore, a plurality of lug grooves 7 are formed in the rib 5 at intervals in the tire circumferential direction on both outer sides of the boundaries 8 and 8 of the ground contact area. The rib 5 is provided with a sipe 6 that communicates with the main groove 1 from the inner side in the tire width direction of the lug groove 7 and three sipes 6 that are open on one side and that go out to the end of the tire.
[0018]
In the above tread pattern, it is preferable that both the sipe 6 provided in each block 3 of the block row and the lug groove 7 provided in the shoulder side rib 5 are provided at the same time as in the illustrated example. Either 6 or the lug groove 7 may be omitted.
[0019]
The pneumatic tire of the present invention has a groove area ratio of 5 to 30%, preferably 5 to 25%, more preferably 5 to 20% in the tread pattern, and the sub groove 2 occupies the total groove area. There are always 8 to 16, preferably 10 to 12 sub-grooves 2 in the region. Furthermore, the number of sipes provided in each block 3 is 1 to 4, preferably 2 to 3. Here, the contact area refers to an area where the tread surface contacts the ground when the tire contacts the flat road surface with JATMA maximum load load and maximum air pressure.
[0020]
Since the tread pattern is configured as described above, when the tire is grounded and the tread surface is deformed, the block is deformed so that the sub-groove is blocked, thereby preventing slipping on the road surface and Generation of frictional vibration noise can be suppressed. In addition, since the sub-groove is blocked by the deformation of the block, it is possible to suppress the generation of air pumping noise derived from the sub-groove. Furthermore, it is better to use ribs on both outer sides of the three main grooves. As a result, noise is not emitted from the outermost main groove to the outside of the tire, so that the effect of reducing outside noise is further increased.
[0021]
The shape of the sub-groove is not particularly limited, but a curve or a straight line having no inflection point is preferable, and a straight line is the best.
[0022]
Further, when sipes are provided in the blocks of the block row, the shearing force that acts greatly in the moving direction of the blocks during braking / driving is dispersed and absorbed by the sipes, so that heel and toe wear can be prevented.
[0023]
In addition, when the lug groove is provided in the shoulder rib, the stress applied to the outer portion in the tire width direction when the tire is in contact with the tire is absorbed by the deformation of the lug groove, and the pressure distribution in the contact area is made uniform. Wear can be prevented.
[0024]
FIG. 2 is a graph showing the relationship between the groove area ratio S occupied by the sub-grooves in the total groove area and the noise level N.
[0025]
This graph shows that the tire size is 185R14 8PR LT, the tread pattern is FIG. 1, the number of sub-grooves occupying the ground contact area is 10, the sub-groove angle with respect to the tire circumferential direction is 60 °, and the sub-groove depth is relative to the main groove depth. The ratio of 60%, the ratio between the maximum value and the minimum value of the sub-groove width (maximum value / minimum value) is 1.30, and the number of sipes in each block is two. 11 types of air with different ratios to the total groove area of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70% It is the result of having tested the outside noise about the entering tire.
[0026]
The noise level is measured by the following measurement method, and the result obtained is the reciprocal of the measurement result of the noise level. In FIG. 1, a rib-pattern tire without a sub-groove (except for the test tire except that no sub-groove is provided). The reciprocal of the noise level measured for (common conditions) was expressed as an index with 100 as the inverse. A larger numerical value indicates that the noise level is reduced.
[0027]
Noise level measurement method:
The vehicle was mounted on a small truck, which is a vehicle conforming to the test tire size, and the coasting noise was measured according to JIS D1015 “Automatic coasting test method”.
[0028]
From the graph shown in FIG. 2, it can be seen that when the groove area ratio of the sub grooves to the total groove area is 5 to 30%, the noise level of the outside noise is reduced as a whole.
[0029]
If the number is less than 5%, the area is too small. Therefore, when the number of sub grooves is constant, the width of the sub grooves is too small. Therefore, when the tire is grounded and the tread surface is deformed, stress from the road surface is further applied to the block 3 even after the sub-groove is blocked, and the block 3 cannot be further deformed. Slip occurs between the two and noise is generated, which is not preferable. If it exceeds 30%, the width of the sub-groove becomes too large when the number of sub-grooves is constant. Therefore, when the tire is grounded and the tread surface is deformed, a space formed by the sub-groove 2 and the road surface remains even after the block 3 is completely deformed, and an air pumping noise is generated, which is not preferable.
[0030]
FIG. 3 is a graph showing the relationship between the number of sub-grooves n distributed in the ground contact area and the noise level N.
[0031]
This graph shows the tire used as a test tire in the test of FIG. 2, the tire size, the sub-groove angle with respect to the tire circumferential direction, the ratio of the sub-groove depth to the main groove depth, and the maximum and minimum values of the sub-groove width. The ratio of the sipe in each block is the same, and the ratio of the groove area to the total groove area of the sub-groove is 20% in common, and the number of sub-grooves in the grounding region is 4, 6, 8 It is the result of having tested the vehicle outside noise about nine types of pneumatic tires made different for each of 10, 10, 12, 14, 16, 18, and 20.
[0032]
The noise level was measured by the same method as in FIG. 2, and the noise level was also displayed as an index according to the same standard as in the test of FIG.
[0033]
It can be seen from the graph of FIG. 3 that an excellent noise level reduction effect is exhibited when the number of sub-grooves in the ground contact region is 8 to 16. If the number is less than 8, the deformation of the tread surface is not sufficiently absorbed by the sub-grooves, so that the tread surface and the road surface slip and a ground frictional vibration noise is generated, which is not preferable. When the number is more than 16, the width of the sub-groove is reduced, and further stress is applied from the road surface even after the sub-groove is closed, so that a ground frictional vibration noise is generated between the tread surface and the road surface. Absent. Moreover, since the rigidity of the block 3 will become small when there are many subgrooves, it is not preferable.
[0034]
4, 5, and 6, when the groove width of the sub groove changes (FIG. 4), when the groove depth of the sub groove changes (FIG. 5), the angle of the sub groove with respect to the tire circumferential direction changes. The result of investigating the influence on the outside noise is shown for each of the cases (FIG. 6).
[0035]
The tires used in each test are the tire size of 185R14 8PR LT, the tread pattern in FIG. 1, the groove area ratio in the total groove area of the sub grooves is 20%, the number of sub grooves in the ground contact region is 10, and each block The number of the sipe is set to 2 in common, and the sub-groove angle is 60 degrees with respect to the tire circumferential direction, and the ratio of the sub-groove depth to the main groove depth is 60, except for changing the sub-groove for the test. %, The ratio between the maximum value and the minimum value of the sub-groove width (maximum value / minimum value) 1.30 was set as a common condition.
[0036]
First, the graph of FIG. 4 shows the ratio W (maximum value / minimum value) of the maximum value and the minimum value of the groove widths of the sub-grooves under the above-mentioned common conditions as 1, 1.1, 1.2, 1.3. , 1.4, the noise level N was measured for five types of pneumatic tires.
[0037]
From FIG. 4, the noise level is good when the ratio W (maximum value / minimum value) of the maximum value and the minimum value of the groove width of the sub-groove is 1 to 1.4. You can see that If it is larger than 1.4, the distribution of the groove width of each sub-groove becomes wide, and air pumping noise derived from the sub-groove is likely to be generated.
[0038]
Next, FIG. 5 shows that the ratio D = 60% of the sub-groove depth to the main groove depth in the above common conditions is changed to 50%, 70%, 80%, 90%, and 100%, respectively. The noise level N was measured for six types of pneumatic tires.
[0039]
FIG. 5 shows that the noise level is good when the sub-groove depth is 50 to 100% of the main groove depth, and more preferably 60 to 100%. It can be seen that the closer to 100%, the more the noise level tends to be reduced. If it is less than 50%, the sub-groove cannot be sufficiently blocked even if lateral stress is applied to the block 3, so that slippage between the tread surface and the road surface is likely to occur, and the air pumping sound derived from the sub-groove Is likely to occur. If it exceeds 100%, the groove is deeper than the main groove 1 and may affect the inside of the tire.
[0040]
FIG. 6 shows the noise level of five types of pneumatic tires in which the angle A = 60 ° with respect to the tire circumferential direction of the sub-groove is changed to 50 °, 55 °, 65 °, and 70 °, respectively, under the above common conditions. N is measured.
[0041]
FIG. 6 shows that the noise level is good when the angle A with respect to the circumferential direction of the sub-groove is 50 to 70 °, and there is a peak near 60 °. If the angle is smaller than 50 °, the rigidity of the tire in the circumferential direction of the block becomes high and the block is difficult to deform, and it is easy to slip between the tread surface and the road surface. The air pumping sound derived from is likely to occur. If it is larger than 70 °, the pattern noise that occurs when the edge of the block contacts the ground tends to increase.
[0042]
FIG. 7 is a graph showing the relationship between the number of sipes si of each block and the uneven wear level a (heel and toe wear).
[0043]
In this graph, the tire size is 185R14 8PR LT, the tread pattern is FIG. 1, the ratio of the sub-groove to the total groove area is 20%, the number of sub-grooves in the ground contact region is 10, and the sub-groove angle with respect to the tire circumferential direction is 60 °, the ratio of the sub groove depth to the main groove depth is 60%, the ratio between the maximum value and the minimum value of the sub groove width (maximum value / minimum value) is 1.30, and the two sipes of each block are closed. The distance between the side edge and the main groove is 1.2 times and 1.4 times the groove width of the main groove, the number of lug grooves is 1.0 times the number of sub grooves, and the groove width of the lug grooves is The point of 0.4 times the groove width is common to each test tire, and the number of sipes of each block si = 2 is 0, 1, 2, 3, 4, 5, 6, 7 It is the result of having tested the uneven wear level a about eight types of pneumatic tires made different for each book. The uneven wear level a is measured by the following measurement method, and the result obtained is the reciprocal of the measurement result of the uneven wear level. In FIG. 1, tires without sipes in each block (except for the points without sipes in the blocks) The reciprocal of the uneven wear level measured for the conditions common to the test tire) was expressed as an index with 100 as the reciprocal. A larger numerical value indicates that the uneven wear level is reduced.
[0044]
Measurement method for uneven wear level a (heel and toe wear):
Tire size 185R14LT, rim size 14 × 5 1 / 2JJ, air pressure 450KPa, mounted on a small truck, and traveled 4000km mainly on slalom running at a speed of 60km / h on the asphalt pavement circuit with constant load (described on the vehicle) Then, the wear step was determined by measuring the difference in height between both ends of the adjacent blocks in the tire circumferential direction.
[0045]
From the graph shown in FIG. 7, it can be seen that when the number of sipes in each block is 1 to 4, the uneven wear level a is reduced. When the number of sipes is 0 (no sipes are provided), the shearing force concentrates on the traveling direction side of each block during braking, and uneven wear (heel and toe wear) occurs, which is not preferable. If the number of sipes is more than 4, the rigidity of the block becomes small, and therefore uneven wear occurs in the same manner, which is not preferable. Preferably, the number of sipes is defined, and the sipe interval is 1.2 times or more the groove width of the main groove.
[0046]
In the pneumatic tire of the present invention, the directionality of the sipe 6 provided in the block 3 is not particularly limited as long as it is in the tire width direction, but when a plurality of sipe 6 are provided, they are provided substantially parallel to each other. Is preferred. By providing substantially parallel, when a shearing force is applied from the road surface to the notched block formed by the sipe 6, the shearing force is likely to be evenly distributed to each sipe, so that uneven wear can be easily suppressed. In addition, the number of sipes provided in each block may be the same as the number of sipes that approximate the size according to the size of the block, but it is better to increase the number of sipes that are significantly larger.
[0047]
When a plurality of sipes 6 are provided, the form of the sipes 6 is preferably open on one side. Moreover, it is preferable that adjacent sipes have the opening sides opposite to each other. By adopting such a sipe arrangement, it is possible to disperse the shear force to the sipe and prevent uneven wear while preventing the block rigidity from being lowered.
[0048]
Moreover, it is preferable that the distance between the closing side end of the sipe 6 and the main groove is 1.2 times or more. If it is smaller than 1.2 times, the block rigidity becomes insufficient and it becomes difficult to prevent uneven wear.
[0049]
Further, the distance between adjacent sipes is preferably 1.2 times or more the groove width of the main groove. 1． If it is less than 2 times, the block rigidity between sipes becomes small, and uneven wear tends to occur.
[0050]
FIG. 8 is a graph showing the relationship between the ratio L of the number of lug grooves 7 to the number of sub-grooves 2 and the uneven wear level b (polygonal wear).
[0051]
The test of the uneven wear level b in FIG. 8 is performed by setting the ratio L of the number of lug grooves to the number of sub-grooves to 0.6, 0.7, 0.8 in the configuration in which the number of sipes in the test of FIG. , 0.9, 1.0, 1.1, 1.2, 1.3, and 1.4, the uneven wear level b was tested for nine types of pneumatic tires.
[0052]
The uneven wear level b in FIG. 8 is measured by the following measurement method, and the obtained result is that the lug groove is not provided in the configuration in which the reciprocal of the measurement result of the uneven wear level is two and the number of sipes in the test of FIG. The reciprocal of the uneven wear level b measured for the tire (conditions common to the test tire except that the lug groove is not provided) was expressed as an index with the reciprocal of 100. A larger numerical value indicates that the uneven wear level is reduced.
[0053]
Measurement method of uneven wear level b (polygonal wear):
Tire size 185R14LT, rim size 14 × 5 1 / 2JJ, air pressure 450KPa, mounted on a small truck, and traveled 4000km mainly on slalom running at a speed of 60km / h on the asphalt pavement circuit with constant load (described on the vehicle) Thereafter, the diameter of the tire passing through the tire width direction center part of the shoulder rib (both outer ribs of the main groove) was measured over the entire circumference of the tire, and the maximum value and the minimum value were calculated to determine the wear step.
[0054]
From the graph shown in FIG. 8, when the ratio of the number of lug grooves 7 to the number of sub-grooves 2 is 0.6 to 1.4, the uneven wear level b (polygonal wear) is a tire not provided with lug grooves. It is understood that 0.8 to 1.3 is preferable. If it is less than 0.6, the number of lug grooves is small, and it is difficult to absorb the stress applied to the outer portion in the tire width direction when the tire is in contact with the tire. If it is larger than 1.4, the number of the lug grooves 7 increases, so that the rigidity of the shoulder ribs (the ribs on both outer sides of the main groove) is lowered, and the effect of preventing uneven wear is easily reduced. Moreover, the wind noise caused by the lug grooves tends to be large. Here, the number of lug grooves and sub-grooves refers to the number of all lug grooves and sub-grooves on the tread surface.
[0055]
In the pneumatic tire of the present invention, the ratio of the groove width of the lug groove 7 to the groove width of the main groove 1 is preferably 0.2 to 0.6. If it is smaller than 0.2, the effect of absorbing the stress applied to the outer side of the lug groove in the tire width direction tends to be small. If it is larger than 0.6, since the width is large, the noise reduction is hindered by the wind noise generated by the lug groove.
[0056]
Further, the rib 5 may be provided with a sipe 6 penetrating in the tire width direction together with the lug groove 6. Since the stress applied to the outer portion in the tire width direction at the time of tire contact is absorbed by deformation of both the lug groove 7 and the sipe 6, the pressure distribution in the contact region can be made more uniform. Therefore, the effect of preventing polygonal wear is increased.
[0057]
【The invention's effect】
As described above, according to the pneumatic tire of the present invention and the other pneumatic tire of the present invention, the block row defined by the sub-grooves is formed between the three main grooves extending linearly in the tire circumferential direction. In the tire, the ratio of the groove area to the total groove area of the sub-groove and the number of the sub-grooves distributed in the ground contact area are set in a specific range, so that when the tire is grounded and the tread surface is deformed, the block is By deforming so that the sub-groove is blocked, the slip of the block against the road surface can be suppressed, and the generation of air pumping noise due to the sub-groove space can be suppressed along with the ground frictional vibration noise. It will be reduced.
[0058]
Further, in the case of a tire in which both outer sides of the three main grooves are formed as ribs as in the pneumatic tire of the present invention and sipes are provided in each block of the block row, noise is generated from the outermost main groove. Prevents it from being released to the outside of the tire, further reducing the noise outside the vehicle and preventing heel-and-toe wear because the shear force acting on the block in the traveling direction during braking is dispersed and absorbed by the sipe. can do.
[0059]
Further, in the case of a tire provided with lug grooves corresponding to 0.6 to 1.4 times the number of sub-grooves outside the ground contact area of the rib as in the other pneumatic tires of the present invention, The stress applied to the outer portion in the width direction is absorbed by the deformation of the lug groove and the pressure distribution in the ground contact region is made uniform, so that polygonal wear can be prevented.
[Brief description of the drawings]
FIG. 1 is a development view illustrating a tread surface of a pneumatic tire according to the present invention.
FIG. 2 is a graph showing a relationship between a groove area ratio S in a total groove area of a sub groove and a noise level N;
FIG. 3 is a graph showing the relationship between the number of sub-grooves n in the ground contact area and the noise level N.
4 is a graph showing a relationship between a ratio (maximum value / minimum value) W of a maximum value and a minimum value of a groove width of a sub groove and a noise level N. FIG.
FIG. 5 is a graph showing a relationship between a ratio D of a sub groove depth to a main groove depth and a noise level N;
6 is a graph showing a relationship between an angle A with respect to a tire circumferential direction of a sub-groove and a noise level N. FIG.
FIG. 7 is a graph showing the relationship between the number of sipes si of each block and the uneven wear level a (heel and toe wear).
FIG. 8 is a graph showing the relationship between the ratio L of the number of lug grooves to the number of sub-grooves and uneven wear level b (polygonal wear).
[Explanation of symbols]
1 Main groove 2 Sub groove 3 Block 4 Block row 5 Rib 6 Sipe 7 Lug groove 8 Boundary of ground contact area

Claims (18)

In a pneumatic tire in which three main grooves extending linearly in the tire circumferential direction are provided on a tread surface, and a block row is formed by communicating the main grooves with a plurality of sub grooves spaced apart in the tire circumferential direction. ,
The outer sides of the three main grooves are formed as ribs, the sub grooves are inclined obliquely with respect to the tire circumferential direction, and the groove area ratio in the total groove area of the sub grooves is 5 to 30%. the the number of sub-grooves to 8-16 present, sipes 1-4 present provided pneumatic tire extending in the tire width direction in each block forming the block row distributed in the ground area.   The pneumatic tire according to claim 1, wherein a ratio (maximum value / minimum value) between a maximum value and a minimum value of the groove width of the sub-groove is set to 1 to 1.4.   The pneumatic tire according to claim 1 or 2, wherein a ratio of a groove depth of the sub groove to a main groove depth is 50 to 100%.   The pneumatic tire according to any one of claims 1 to 3, wherein an angle of the sub groove with respect to a tire circumferential direction is set to 50 to 70 °. The pneumatic tire according to any one of claims 1 to 4 , wherein the sipes are substantially parallel to each other. The pneumatic tire according to any one of claims 1 to 5 , wherein the sipe is open on one side and the opposite sides are opened between adjacent sipes. The pneumatic tire according to claim 6 , wherein the distance between the closed side end portion of the sipe and the main groove is 1.2 times or more the groove width of the main groove. The pneumatic tire according to claim 6 or 7 , wherein a distance between sipes in each block is 1.2 times or more a groove width of the main groove. The pneumatic tire according to any one of claims 1 to 8, wherein a plurality of lug grooves are provided at a shoulder end of the rib at intervals in the tire circumferential direction. The pneumatic tire according to claim 9 , wherein the number of the lug grooves is 0.6 to 1.4 times the number of the sub grooves. The pneumatic tire according to claim 9 or 10 , wherein the groove width of the lug groove is 0.2 to 0.6 times the groove width of the main groove. The pneumatic tire according to claim 9, 10 or 11 , wherein a sipe penetrating the rib in the tire width direction is provided. Three main grooves extending linearly in the tire circumferential direction are provided on the tread surface, and a plurality of sub-grooves communicate with each other at intervals in the tire circumferential direction to form a block row. In pneumatic tires with ribs on both outer sides of the main groove,
The sub-groove is inclined obliquely with respect to the tire circumferential direction , the groove area ratio in the total groove area of the sub-groove is 5 to 30%, and the number of sub-grooves distributed in the ground contact region is 8 to 16 And provided with a plurality of lug grooves at intervals in the tire circumferential direction outside the ground contact area on the rib , and the number of the lug grooves is 0.6 to 1.4 times the number of the sub grooves. tire.   The pneumatic tire according to claim 13, wherein a ratio (maximum value / minimum value) between a maximum value and a minimum value of the groove width of the sub-groove is set to 1 to 1.4.   The pneumatic tire according to claim 13 or 14, wherein a ratio of a groove depth of the sub groove to a main groove depth is 50 to 100%.   The pneumatic tire according to any one of claims 13 to 15, wherein an angle of the sub-groove with respect to a tire circumferential direction is set to 50 to 70 °. The pneumatic tire according to any one of claims 13 to 16, wherein the groove width of the lug groove is 0.2 to 0.6 times the groove width of the main groove.   The pneumatic tire according to any one of claims 13 to 17, wherein a sipe penetrating in the tire width direction is provided in the rib.

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