JP2007153239A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict pitch noise due to lag treads without changing key design of a tread pattern so as to improve quietness of a vehicle, in regard to a pneumatic tire having a ribbed tread pattern. <P>SOLUTION: In the pneumatic tire provided with a rib 14 provided with lug grooves having ribbed parts 14a continued in the circumferential direction and wing parts 14b divided by the lug grooves 15, a nearly triangular small hole area 14c, which is formed by arranging multiple small holes 14h with an equal interval and having length along the tire cross direction at 0.1 to 1.0 in relation to the width of the wing part 14b and having length along the tire circumferential direction at 0.3 to 1.0 in relation to a circumferential interval of the lag tread 15 and 15, is provided on a circumferential groove 11d side of a line connecting two circumferential end points of each of the wing parts 14b of the rib 14 with lag treads. With this structure, a load burden to the wing part 14b is effectively shifted to the ribbed part 14a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a rib-shaped tread pattern in which a lug groove having one end terminating in a land portion is disposed.

In recent years, with the quietness of vehicles, the contribution of noise caused by tires to automobile noise has increased, and the reduction thereof has been demanded. As the cause of the tire noise, there are ground frictional vibration sound that occurs when the tire contacts the road surface and road surface noise caused by unevenness of the road surface, but in the case of a passenger car, it is particularly formed on the tire tread surface. The ratio of pattern noise due to the tread pattern is large. In particular, when the tread pattern discontinuous part comes into contact with the ground, such as a lag pattern or block pattern, the hitting sound generated by the collision with the road surface is a frequency (pattern pitch frequency) depending on the pitch interval of the lag grooves and blocks and the vehicle speed. This is also called pitch noise.
As a method for reducing the tire noise due to the hitting sound, a method for preventing a single frequency from having a peak by, for example, increasing the pitch interval has been proposed.
Moreover, about the lug groove, the method of reducing the said impact sound is performed by making it into a lug groove with an angle with respect to the tire width direction.

On the other hand, in tires having a block pattern, it has been pointed out that if the lug grooves are angled, the block shape approaches a parallelogram, resulting in problems such as reduced block rigidity and uneven wear. Therefore, as shown in FIG. 15 (a), on the circumferential groove side of the block 50, the width 50A on the first grounding side of the block 50 is wide, and the width gradually decreases along the tire circumferential direction. By providing a chamfered portion 51 whose height is lower than the virtual contour line of the tire crown portion and gradually bringing the block 50 into contact with the ground, the timing of stepping on and kicking out is shifted, and the time axis is A method of reducing the pitch noise by dispersing the pitch noise, or a kicking edge 60 from the stepping edge 60A of the block 60 as shown in FIG. Until the height of the step 60 is equal to the virtual contour of the tire crown, and a flat portion 61 having a predetermined width in which the extension direction is inclined with respect to the tire circumferential direction is provided. The kicking edge 60B that is finally brought into contact with the ground is provided with low ground portions 62 and 63 that gradually decrease in height toward the circumferential groove side so that the block 60 is grounded gradually. A method has been proposed in which the pitch noise is reduced by gradually moving away from the road surface to shift the stepping and kicking timings (see, for example, Patent Document 1).
JP 2003-25810 A

By the way, as a tread pattern of an automobile tire, as shown in FIG. 16, a lug groove 73 having one end opened on the circumferential groove 71 side and the other end terminated in a land portion defined by the circumferential grooves 71, 71. A tread pattern including a land portion (rib with a lug groove) 75 having a rib-like portion 72 having a circumferential shape and a wing portion 74 in which the lug groove is disposed is also often used. Even in a tire having such a tread pattern, the wings 74 defined by the lug grooves 73 are discontinuous in the tread pattern, so that pitch noise depending on the pitch of the lug grooves 73 is generated.
In a tread pattern having rib-like portions 72 that are continuous in the circumferential direction, such as the ribs 75 with the lug grooves, the extension direction of the lug grooves 73 has an angle with respect to the tire width direction to prevent noise. Therefore, when the foot is stepped on or kicked out, the contact width of the land portion gradually changes. Therefore, when the lug groove 73 is inclined, not only the pitch noise can be stretched on the time axis, but the rib-like portion 72 does not have a frequency component of the pattern pitch. Even without providing the chamfered portion 51 and the low ground portions 62 and 63, the noise level is lower than that of a tire having a block pattern.
However, when the angle of the lug groove 73 with respect to the tire width direction is increased, not only the steering stability, which is a feature of the tire having the lug groove, is deteriorated, but also there is a risk that uneven wear is likely to occur. As described above, since there is a limit to increasing the angle of the lug groove 73, it is difficult to reduce the pitch noise without changing the basic tone of the tread pattern.
In addition, it is conceivable to provide the chamfered portion 51 and the low ground portions 62 and 63 as described above in the lug grooved rib 75. However, in order not to lose the ground contact area excessively in the surface shape processing, 0 Since it is perfect to have a drop height of about 5 mm, the improvement in noise performance is not always sufficient, and if the surface shape is improved too much, uneven wear performance may deteriorate. Concerned.

  The present invention was made in view of conventional problems, and in a pneumatic tire having a rib-like tread pattern, without changing the basic tone of the tread pattern, the pitch noise caused by the lug groove is suppressed, The purpose is to improve the quietness of the vehicle.

In the invention according to claim 1 of the present application, the surface of the tire tread is partitioned by a circumferential groove extending along the tire circumferential direction, and one end is opened to the circumferential groove side and the other end is in the land portion. At least one row of land portions having a plurality of inclined lug grooves that are terminated and inclined with respect to the tire width direction and that have rib-like portions that are continuous in the circumferential direction and wing portions that are partitioned by the lug grooves are provided. The pneumatic tire is characterized in that a large number of small holes are provided in the circumferential groove side on the tire ground contact surface side of the wing portion with respect to the line connecting the circumferential end points of the wing portion. .
More specifically, the circumferential end point is the end point P1, which is the first point at which the substantially parallelogram-shaped wing section defined by the inclined lug groove steps in during normal rotation of the tire, as shown in FIG. The end point P2, which is a point to be inserted, is indicated.

The invention according to claim 2 is the pneumatic tire according to claim 1, wherein when the length of the lug groove in the tire width direction is L1, and the width of the region where the small hole is provided is L3, The region width L3 satisfies 0.1 ≦ (L3 / L1) ≦ 1.0.
According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the circumferential interval between the lug grooves is L2, and the circumferential length of the region where the small holes are provided is L4. In this case, the region length L4 satisfies 0.3 ≦ (L4 / L2) ≦ 1.0.

The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the cross-sectional area in the depth direction of the small hole is changed.
The invention according to claim 5 is the pneumatic tire according to any one of claims 1 to 4, wherein the depth of the small hole and the circumferential groove side from the line connecting the circumferential end points of the wing portion. The one formed closer to the end point located at (end point P3 shown in FIG. 3) is deeper.
The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 5, wherein a small hole having a predetermined angle with a direction perpendicular to the tire contact surface is provided in the depth direction. is there.
A seventh aspect of the present invention is the pneumatic tire according to any one of the first to sixth aspects, wherein the density of the small holes is increased as the end point P3 is approached.
The invention according to claim 8 is the pneumatic tire according to any one of claims 1 to 7, wherein the cross-sectional area of the small hole is increased as the end point P3 is approached.

According to the present invention, in a pneumatic tire provided with at least one row of land portions (ribs with lug grooves) having rib-shaped portions continuous in the circumferential direction and wing portions partitioned by lug grooves, On the tire ground contact surface side, many small holes are provided on the circumferential groove side of the line connecting the circumferential end points of the wing part to reduce the compression rigidity of the wing part, and the load burden on the wing part is reduced. Since it is shifted to a rib-like part that is connected to the circumferential part and is continuous in the circumferential direction, the striking at the time of stepping in and kicking out input to the wing part while maintaining the shape of the ground contact surface at the outer contour of the tire The power can be reduced. Therefore, it is possible to effectively reduce the pitch noise caused by the lug groove without deteriorating the uneven wear performance.
At this time, when the width of the wing portion is L1 and the width of the region where the small hole is formed is L3, the L3 is in a range satisfying 0.1 ≦ (L3 / L1) ≦ 1.0, When the circumferential interval between the lug grooves is L2, and the circumferential length of the region provided with the small holes is L4, the region length L4 is set to 0.3 ≦ (L4 / L2) ≦ 1.0. If the range satisfies the above, it is possible to reliably reduce the pitch noise.
Further, when forming the small hole, the depth of the small hole formed closer to the end point P3 located on the circumferential groove side than the line connecting the circumferential end points of the wing portion is increased, or the cross-sectional area is increased. If the compression rigidity on the circumferential groove side of the wing portion is reduced by increasing the diameter or by giving a distribution such that the density of the small holes becomes higher as the end point P3 is closer, the above-mentioned Pitch noise can be further reduced.

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
FIG. 1 is a view showing an example of a tread pattern of a pneumatic tire 10 according to the best mode of the present invention, and FIG. 2 is a perspective view showing an essential part thereof. In each figure, 11a-11d is a circumferential groove extending along the tire circumferential direction, and 12 is an outer side in the tire width direction from circumferential grooves 11a, 11d located on the outer side in the tire width direction among the circumferential grooves 11a-11d. , 13 is a first land portion located in the center in the tire width direction, 14 and 14 are located on both sides of the central land portion 13, and one end thereof is the circumferential groove 11 a or the circumferential groove. A second land portion 16 having a plurality of lug grooves 15 formed at a predetermined angle with respect to the tire width direction, opened to the 11d side and terminated at the other end in the land portion. A shoulder block defined by the grooves 11a and 11d and the lateral grooves 12.
The second land portion 14 includes a rib-like portion 14a extending continuously in the tire circumferential direction and the lug groove protruding from the rib-like portion 14a toward the circumferential groove 11d (or the circumferential groove 11a). In this embodiment, each wing part 14b of the second land parts 14 and 14 is integrated with the rib-like part 14a. A substantially triangular small hole region 14c in which a large number of small holes 14h are formed is provided on the tire contact surface side opposite to the side. Hereinafter, the second land portions 14 and 14 are referred to as lug grooved ribs.

The small hole 14h basically works in a direction to lower the surrounding ground pressure. The reason is the incompressibility of rubber. That is, since the noise input corresponding to the pitch acts as a force for deforming the rubber, if the ground contact pressure in the circumferentially discontinuous portion such as the wing portion 14b can be effectively reduced, the load on that portion is The circumferential continuous portion (rib-shaped portion 14a) without pitch input bears this. Further, in the wing part 14b, the further away from the rib-like part 14a that is a circumferentially continuous part, the behavior is closer to a block that is partially partitioned by a groove, so the contribution as noise input is circumferential. The closer to the groove 11d side, the larger.
Therefore, in this example, as shown in FIGS. 3A and 3B, the circumferential end point P1 and the end point P2 of the wing portion 14b, which are the first step point or the last step point when the tire rolls. A length (region width) along the tire width direction including an end point P3 (hereinafter, P3 is referred to as an intermediate end point) that is not a circumferential end point on the circumferential groove side on the circumferential groove 11d side of the line connecting ) Is L3, and the circumferential length (region length) along the outer contour of the tire is L4, by providing a substantially triangular small hole region 14c formed by arranging a large number of small holes 14h provided at equal intervals, As shown in FIG. 3 (c), the ground pressure of the wing part 14b can be reduced as the distance from the rib-like part 14a continuous in the circumferential direction decreases. Rib shape connected to the portion 14b and continuous in the circumferential direction It can be shifted to 14a.

Here, the fact that the shape of the small hole region 14c is substantially triangular will be described.
It is considered that the impact input (= force or load) when the edge hits the road surface when stepping on is concentrated in a portion where there is no small hole 14h, and the noise input is reduced in the vicinity of the small hole 14h. Therefore, in order to reduce the timing at which this impact input is concentrated in the stepping side edge and the kicking side edge (near the end point P1 and end point P2), the first step point or the last step point is It is desirable that the “portion without a hole”. That is, in order to receive the load input as long as possible, it is better not to provide the small hole 14h in the vicinity of the circumferential end points P1 and P2 of the wing portion 14b. In order to satisfy such a condition, the small hole region 14c may be provided on the circumferential groove 11d side with respect to the line connecting the circumferential end points P1 and P2 of the wing portion 14b.
That is, as an appropriate shape of the small hole region 14c, as shown in FIG. 3A, the length along the tire width direction is uniform as it goes from the end point P1 side to the end point P2 side. For example, as shown in FIGS. 4A and 4B, the change in length along the tire width direction is small on the end point P1 side but large on the end point P2 side. Such as a shape that is larger on the end point P1 side and smaller on the end point P2 side than the line connecting the circumferential end point P1 and the end point P2 of the wing part 14b. If the shape includes the end point P3 that is not the circumferential end point on the circumferential groove side with the region width of L3 and the region length of L4, the contact pressure of the blade part 14b can be reduced, and the blade The load on the portion 14b 14b can be shifted to the circumferentially continuous rib-like portion 14a, so that the striking force when stepping on or kicking out the wing portion 14b can be reduced, and the lug groove The pitch noise caused by 15 can be greatly reduced.
In addition, as in the present invention, instead of processing the surface shape, if the small hole region 14c is provided to reduce the contact pressure of the wing portion 14b, the surface shape of the pattern basically matches the outer contour of the tire. In addition to being less susceptible to uneven wear, the shear force in the ground contact surface, which causes wear, is reduced by the effect of reducing the contact pressure by the small hole 14h, greatly affecting the uneven wear that has been a concern with conventional tires. Can be made smaller.

At this time, as the region width L3 of the small hole region 14c shown in FIG. 3A, 0.1 ≦ (L3) when the width (wing portion width) along the tire surface of the wing portion 14b is L1. / L1) It is preferable to set in a range satisfying ≦ 1.0.
When the width ratio (L3 / L1), which is the ratio of the region width L3 to the blade width L1, is less than 0.1, the effect of providing the small hole 14h is small, and the load burden of the blade 14b is a continuous portion. Since it cannot be sufficiently shifted to a certain rib-like portion 14a, reduction of pattern noise cannot be expected. Further, the upper limit value of the width ratio being 1.0 means that the small hole region 14c is provided only in the wing portion 14b. That is, if the small holes 14h are also provided in the rib-shaped portion 14a, the ground pressure of the rib-shaped portion 14a is reduced, so that pattern noise may be increased. Therefore, the range of the width ratio (L3 / L1) is preferably 0.1 to 1.0.
Such small holes 14h, unlike narrow grooves such as sipes, do not significantly change the behavior of the wings 14b themselves, so that noise characteristics can be improved without adversely affecting uneven wear or steering stability. Can do.

  Further, the region length L4 of the small hole region 14c satisfies 0.3 ≦ (L4 / L2) ≦ 1.0, where L2 is the circumferential interval (blade portion length) of the lug grooves 15 and 15. It is preferable to set the range. When the length ratio (L4 / L2), which is the ratio of the region length L4 to the wing length L2, is less than 0.3, the effect of providing the small holes 14h is small, and therefore the pattern noise cannot be reduced. Further, since the small hole region 14c is provided on the circumferential groove 11d side with respect to the line connecting the circumferential end point P1 and the end point P2 of the wing portion 14b, even if the upper limit value of the length ratio is 1.0, the vicinity of the end point P2 Then, since there is almost no small hole 14h, it becomes a so-called “part without a hole”, so there is no problem.

  Thus, according to the best mode, the lug on the surface of the tire tread continuously extends in the tire circumferential direction and the lug protrudes from the rib-shaped portion 14a toward the circumferential groove 11d. In a pneumatic tire having a tread pattern provided with ribs 14 with lug grooves having a plurality of wing parts 14b partitioned by grooves 15, 15, circumferential end points P1 of the wing parts 14b of the ribs 14 with lag grooves The length L3 along the tire width direction is 0.1 to 1.0 with respect to the width L1 of the wing portion 14b on the circumferential groove 11d side of the line connecting the end point P2 and along the tire circumferential direction. A small hole formed by arranging a large number of small holes 14h provided at equal intervals in a substantially triangular shape having a length L4 of 0.3 to 1.0 with respect to the circumferential distance L2 of the lug grooves 15, 15. Since the region 14c is provided, the wing portion The ground pressure of 4b can be effectively reduced, the load bearing of the blade portion 14b can be effectively shifted to the rib-like portion 14a. Therefore, the striking force at the time of depressing and kicking input to the wing portion 14b can be reduced, and the pattern noise caused by the lug groove 15 can be greatly reduced.

In the above-described embodiment, the case where the small holes 14h having a uniform cross-sectional area in the depth direction has been described. However, the small holes 14h are formed in the ribs 14 with the lug grooves, particularly in the blade 14b. Since it is only necessary to obtain a distribution of rigidity, the shape, size, depth direction, and the like of the small holes are not necessarily uniform.
By the way, the rigidity difference is larger when the small hole is deeper. Therefore, in order to create a contact pressure distribution as shown in FIG. 3C, it is necessary to reduce the contact pressure as it approaches the intermediate end point P3 that is not the end point in the circumferential direction on the circumferential groove side. is there. Therefore, for example, as shown in FIGS. 5A and 5B, it is preferable to make the small holes near the intermediate end point P3 deeper or to increase the density of the small holes as shown in FIG. Alternatively, as shown in FIG. 7, the cross-sectional area of the small hole may be increased by increasing the diameter of the small hole near the intermediate end point P3.
Further, the small hole may have a cross-sectional area that changes in the depth direction as shown in FIGS. Thereby, even if the hole diameter in the contact surface is the same, the cross-sectional area of the small hole 14h can be changed. Further, when the wall angle is attached to the lug-grooved rib 14 or the wing portion 14b, as shown in FIGS. 9A and 9B, the extending direction of the small hole 14h is adjusted to the groove wall angle. A hole deeper than the tread gauge can be easily formed.

  Further, the present invention is a tread pattern in which the rib-like portion 14a is divided by a narrow groove (sipe) 17 having a groove width of 1 mm or less, as shown in FIGS. 10 (a) and 10 (b). Even so, it is applicable. This is because the width of the narrow groove 17 is narrower than the width of the lug groove 15 and closes in the ground plane, so that it is difficult for noise to be input. This is because it is sufficient to target. Similarly, when there is a distribution in the lug groove width, pitch noise can be effectively reduced by providing the small hole 14h in a portion having a wide width as viewed from the circumferential cross section.

A tire (Example 1) having a tread pattern provided with rib portions with lug grooves in which a large number of small holes 14h are formed in the wing portion 14b according to the present invention shown in FIG. 1 was manufactured, and tire noise was measured. In the tread pattern, the width of the wing portion is L1 = 25 mm, L2 = 30 mm, and the small hole region has a substantially triangular shape with a region width of L3 = 20 mm and a region length of L4 = 25 mm. 44 small circular holes / block having a diameter of 1 mm and a depth of 7 mm were provided at equal intervals. For comparison, a tire (conventional example) having a tread pattern provided with rib portions 75 with lug grooves in which small holes are not formed in the wing portion 14b shown in FIG. 16 was manufactured, and tire noise was measured.
The tire sizes of all the tires are 235 / 50R17, the load is 4.8 kN, and the tire internal pressure is 210 kPa. The tire noise is measured by running a test tire on a rotating drum at a speed of 80 km / hr and using a microphone installed at a position 1 m in the tire lateral direction and 0.25 m in height. The sound pressure level to be measured was measured, and the sound pressure level was evaluated by an index with the conventional example as 100. At this time, the demand level is an improvement (reduction) of 10 or more in the index as a value that can be expected to be effective in the actual vehicle test.
As a result of the test, the index of the sound pressure level of the tire having the tread pattern of the present invention of Example 1 was 82. As a result, it was confirmed that the tire having the tread pattern of the present invention has significantly improved tire noise as compared with the conventional tire.

Next, the results of measuring the sound pressure level with the region length fixed at L4 = 25 mm and the region width varied from L3 = 1.25 mm to 25 mm are shown in FIGS. The small holes were circular with a diameter of 1 mm and a depth of 7 mm, as in Example 1, and the density of the small holes was also the same as in Example 1. In FIG. 11B, the horizontal axis represents the width ratio (L3 / L1), and the vertical axis represents the sound pressure level index (result index) K where the sound pressure level of the conventional example is 100.
As is apparent from FIGS. 11A and 11B, the result index is best when K = 81 in Example 5 where (L3 / L1) is 0.7, but the value of (L3 / L1) is 0. Also in Examples 2 to 4 and Examples 6 and 7 in the range of .1 to 1.0, an improvement of 10 or more was observed in the index, and it was confirmed that the value can be expected in the actual vehicle test. .
On the other hand, in Comparative Example 1 in which the value of (L3 / L1) is 0.05, K = 94, and the improvement effect was not seen so much.

12A and 12B show the results of measuring the sound pressure level while fixing the region width to L3 = 20 mm and changing the region length from L4 = 6 mm to 30 mm. The small holes were circular with a diameter of 1 mm and a depth of 7 mm, as in Example 1, and the density of the small holes was also the same as in Example 1. In FIG. 12B, the horizontal axis represents the length ratio (L4 / L2), and the vertical axis represents the sound pressure level index (result index) K when the conventional sound pressure level is 100.
As is clear from FIGS. 12A and 12B, the result index is best in Example 9 where (L4 / L2) is 0.5, with K = 76, but the value of (L4 / L2) is 0. Also in Examples 8 and 9 and Examples 11 and 12 in the range of 3 to 1.0, an improvement of 10 or more was observed in the index, and it was confirmed that the value could be expected in the actual vehicle test. .
On the other hand, in Comparative Example 2 in which the value of (L4 / L2) is 0.2, K = 98, and the improvement effect was not seen so much.

Next, the formation area width of small holes is fixed to L2 = 20 mm, L4 = 25 mm, the number of holes is fixed to 44 / block, and different tread patterns such as small hole depth, density distribution, opening size, formation area, etc. The tires (Example 13 to Example 17) having the above were manufactured, and the sound pressure level was measured.
In Example 13, as shown in FIGS. 5A and 5B, the depth of the small holes is distributed between 3 mm and 9 mm, and the depth of the small holes is made deeper as it is closer to the intermediate end point P3. Thus, the result index was K = 80, and it was found that the noise reduction effect was further improved as compared with Example 1 where the hole depth was all 7 mm.
In the fourteenth embodiment, as shown in FIG. 6, the density of the small holes is increased as the distance from the intermediate end point P3 is increased. It was found that the effect was further improved.
In Example 15, as shown in FIG. 7, the diameter of the small holes was distributed between 0.8 mm and 3 mm, and the diameter of the small holes near the intermediate end point P3 was increased. The result index was K = 76. It was found that the noise reduction effect was greatly improved.
Further, in Example 16, as shown in FIG. 13, the hole diameters of the openings are combined at random, and the total area of the holes is the same as that in Example 1, and the result index is K = 83 and almost the same improvement as in Example 1 were observed.
Further, in Example 17, as shown in FIGS. 14A and 14B, small holes 14h and 14H having different hole depths are provided, and the diameters of the small holes are different from those of the surrounding small holes. The total number of the small holes 14h and 14H and the depth of the seventeenth embodiment are made to coincide with those of the first embodiment. The result index of Example 17 was K = 81, which was almost equivalent to Example 1. Thus, when it arrange | positions so that a hole depth may differ from the surrounding small hole, it has an advantage that the possibility of destruction of the block (wing | blade part) by generation | occurrence | production of the crack of a hole bottom becomes small.

  Thus, according to the present invention, since the pitch noise caused by the lug groove can be suppressed without changing the basic tone of the tread pattern, the quietness of the vehicle can be easily improved.

It is a figure which shows the tread pattern of the pneumatic tire which concerns on the best form of this invention. It is a perspective view which shows the outline | summary of the rib with a lug groove which concerns on this best form. It is a figure which shows the detail of the wing | blade part which concerns on this best form, and the contact pressure distribution of the rib with a lug groove. It is a figure which shows the other form of the small hole area | region by this invention. It is a figure which shows an example of the distribution state of the small hole by this invention. It is a figure which shows an example of the distribution state of the small hole by this invention. It is a figure which shows an example of the distribution state of the small hole by this invention. It is a figure which shows the shape of the small hole by this invention. It is a figure which shows the shape of the small hole by this invention. It is a figure which shows the other form of the rib with a lug groove | channel by this invention. It is a figure which shows the relationship between the width ratio of a small hole area | region, and a sound pressure level. It is a figure which shows the relationship between the length ratio of a small hole area | region, and a sound pressure level. It is a figure which shows the other example of the distribution state of the small hole by this invention. It is a figure which shows the other example of the distribution state of the small hole by this invention. It is a figure which shows the structure of the block of the pneumatic tire which has the conventional block pattern. It is a figure which shows the tread pattern provided with the conventional rib with a lug groove.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire, 11a-11d Circumferential groove | channel, 12 Lateral groove, 13 1st land part, 14 2nd land part (rib with a lug groove), 14a Rib-shaped part, 14b Wing part,
14c Small hole area, 14h Small hole, 15 lug groove, 16 shoulder block.

Claims (8)

  The surface of the tire tread is partitioned by a circumferential groove extending along the tire circumferential direction, and one end opens to the circumferential groove side and the other end terminates in the land portion, and is inclined with respect to the tire width direction. A pneumatic tire provided with at least one row of land portions each having a plurality of inclined lug grooves and having rib-like portions continuous in the circumferential direction and wing portions partitioned by the lug grooves, An air characterized in that a large number of small holes are provided in the circumferential groove side from the line connecting the circumferential end points that are the first step or the last step of the wing on the tire contact surface side. Enter tire.   When the length of the lug groove in the tire width direction is L1, and the width of the region provided with the small hole is L3, the region width L3 satisfies 0.1 ≦ (L3 / L1) ≦ 1.0. The pneumatic tire according to claim 1.   When the circumferential interval between the lug grooves is L2, and the circumferential length of the region provided with the small holes is L4, the region length L4 is 0.3 ≦ (L4 / L2) ≦ 1. The pneumatic tire according to claim 1 or 2, wherein 0 is satisfied.   The pneumatic tire according to any one of claims 1 to 3, wherein a cross-sectional area in the depth direction of the small hole is changed.   The depth of the small hole is made deeper as it is formed closer to the end point located on the circumferential groove side than the line connecting the circumferential end points of the wing part. 4. The pneumatic tire according to any one of 4 above.   The pneumatic tire according to any one of claims 1 to 5, wherein a small hole having a predetermined angle with a direction perpendicular to the tire ground contact surface is provided.   The density of the small holes is made higher as it is formed closer to the end point located on the circumferential groove side than the line connecting the circumferential end points of the wing part. The pneumatic tire according to any one of the above. The cross-sectional area of the small hole is made larger as it is formed closer to the end point located on the circumferential groove side than the line connecting the circumferential end points of the wing part. The pneumatic tire according to any one of 7.

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