JPH07186633A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To obtain the excellent brake performance and the drive performance on an ice snow road or a wet road surface, by arranging fine ribs having the angle formed between the longitudinal direction and the tire circumferential direction in a specific range in an arraged state in the tire width direction, in the grounded land part of a tread. CONSTITUTION:On the tread 12 of a pneumatic time 10 a circumferential direction groove 14 which extends in a zigzag form in the tire circumferential direction is farmed on a tire equator plane CL, and a circumferential direction groove 16 which extends in a straigt-line form in the tire circumferential direction is formed between the circumferential direction grooves 14. Further, on the tread 12, a plurality of lateral grooves 18 which extend in the tire width direction are formed in a prescribed interval, and a plurality of blocks 20 are dividedly formed on the tread 12. In this case, a fine rib 26 having a nearly rectangular shaped section is formed on the tread surface in each block 2. The fine rib 26 is formed within a range of the angle formed between the longtitudinal direction and the tire circumferential direction of 0-40 in the grounded part of the tread, and the width of the top part is set to 5mum-2.0mm, height is set to 5mum-1.0mm, and the interval between ths contiguous fine rib is set to 5mum-1.5mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a tread pattern, and more particularly to a pneumatic tire having excellent braking performance / driving performance on icy snow roads, wet road surfaces and the like.

[0002]

2. Description of the Related Art As a method of improving braking performance / driving performance on icy and snowy roads and wet road surfaces, on the snow, the edges and lateral grooves of the ground contact areas such as blocks are increased to catch snow.
On ice, it is important to increase the edge component by arranging widthwise sipes, increase the groove area on the wet road surface to improve drainage, and cut the water film by sipes.

On the other hand, there is a spike tire as a winter tire used when traveling on a snowy road, but this spike tire is a social problem because it damages a dry paved road and generates dust, and due to sipes and the like. The mainstream is shifting to studless tires with more edge components.

[0004]

By the way, in order to increase the width direction edge component which is effective in braking performance and driving performance on ice and snow road surface, if a lateral groove is further added and the ground contact land portion such as a block is shredded beyond the limit. In some cases, the rigidity of the ground contact portion such as a block, especially in the circumferential direction, may be reduced, which may rather reduce the braking performance / driving performance, and the wear resistance performance may be deteriorated.

Similarly, when the number of sipes is increased, if the number of sipes is increased beyond the limit, the rigidity of the land contact land portion such as the block may be reduced, and the braking performance / driving performance may be deteriorated. The uneven wear resistance also deteriorates.

In consideration of the above facts, an object of the present invention is to provide a pneumatic tire capable of further improving braking performance / driving performance on ice / snow roads and wet road surfaces as compared with conventional tires without deteriorating other performances.

[0007]

According to a first aspect of the present invention, in a pneumatic tire having a tread pattern, an angle between a longitudinal direction and a tire circumferential direction at a ground contact land portion of the tread is 0 ° to 40 °. It is characterized in that fine ribs having a range are arranged side by side in the tire width direction.

The invention described in claim 2 is the same as claim 1.
In the pneumatic tire according to the item 1, the fine ribs have a top width of 5 μm to 2.0 mm and a height of 5 μm to 1.0 m.
m, and the distance between adjacent fine ribs is 5 μm to 1.5 mm.

[0009]

When the pneumatic tire of the present invention is run on an icy and snowy road, for example, water is generated due to pressure and friction when the tread and ice come into contact with each other. This water, which causes a decrease in frictional force, is taken in by the fine groove portion between the fine ribs provided on the tread surface of the ground contact land (for example, a block), and through the fine groove portion to the outside of the ground contact land. Is discharged. For this reason,
The water film between the tread surface and the road surface is removed, and the ground contact with the road surface is improved.

Further, since the fine ribs are relatively low, densely arranged, and arranged in the circumferential direction or within a range where the angle with respect to the circumferential direction is relatively small, the circumferential rigidity of the ground contact land may be lowered. Instead, braking performance and driving performance can be improved on icy and snowy road surfaces, and overall performance improvement as a pneumatic tire can be achieved.

The distance between adjacent fine ribs is 5 μm.
When it is less than 1.5 mm, it is not preferable because the fine grooves between the fine ribs cannot sufficiently discharge the water generated between the fine rib and the ice surface, and when it exceeds 1.5 mm, the fine grooves are formed especially during running or braking. There is a risk of crushing, and the initial drainage effect cannot be obtained.

Further, if the height of the fine ribs is less than 5 μm, it is not preferable because water generated between the fine ribs and the ice surface cannot be sufficiently discharged.
It is not preferable because the moldability for molding the pneumatic tire is deteriorated, and the rigidity of the tread surface is excessively decreased when traveling on a dry road surface.

Further, if the width of the top of the fine rib is less than 5 μm, the fine groove may be crushed and the initial drainage effect cannot be obtained, which is not preferable, and if it exceeds 2.0 mm, the number of fine groove portions is increased. It becomes too small to obtain the drainage effect.

If the arrangement angle of the fine ribs with respect to the equatorial plane of the tire exceeds 40 °, the drainage effect of the fine grooves is reduced, which is not preferable. Therefore, the angle is set to a relatively small angle of 40 ° or less.

[0015]

【Example】

[First Embodiment] A first embodiment of the pneumatic tire of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the tread 12 of the pneumatic tire 10 (tire size 195 / 65R15) of this embodiment has a tire equatorial plane CL and a tire equatorial plane CL.
A circumferential groove 14 extending in a zigzag shape in the tire circumferential direction (arrow S direction) is provided on both sides in the tire width direction (arrow W direction), and between the circumferential groove 14 and the circumferential groove 14. A circumferential groove 16 linearly extending in the tire circumferential direction is provided.

Further, the tread 12 is provided with a plurality of lateral grooves 18 extending in the tire width direction at predetermined intervals in the tire circumferential direction. The plurality of lateral grooves 18 and the aforementioned circumferential groove 14 and circumferential groove. 16 and tread 12
A plurality of blocks 20 are defined therein.

The pneumatic tire 10 of this embodiment is used as a winter studless tire, and the tread rubber forming the tread 12 has a hardness (0 °).
C, JIS-A) is 50 degrees, and the loss coefficient tan δ
(Peak position) is -45 ° C, dynamic elastic modulus (-20 ° C)
C, 0.1% strain) is 180 kgf / cm ² .

When used as a winter studless tire, the tread rubber has a hardness (0 ° C, JIS-
A) is 40 to 68 degrees, loss coefficient tan δ (peak position)
Is -30 ° C or less, dynamic elastic modulus (-20 ° C, 0.1%
The strain) is preferably 300 kgf / cm ² or less.

Here, when the hardness of the tread rubber is less than 40 degrees, it is too soft and inferior in wear resistance, and when it is higher than 68 degrees, it is too hard and the contact area with the snow and snow road surface is reduced, resulting in braking performance and driving performance. Etc. are inferior, which is not preferable. Further, if the loss coefficient tan δ (peak position) is higher than −30 °, it is not preferable because it is too rigid on the ice and snow road surface and the contact area is reduced, resulting in poor braking performance and driving performance. Furthermore, the dynamic elastic modulus is 30
If it is higher than 0 kg / cm ² , it is not preferable because it is too rigid on the ice and snow road surface and the contact area is reduced, resulting in poor braking performance and driving performance.

On the other hand, the circumferential groove 14, the circumferential groove 16 and the lateral groove 18 have a groove depth of 8 mm or more in terms of drainage and life.
The groove width is preferably 3 mm or more, and the negative ratio of the tread surface of the tread 12 is preferably 25 to 65% in terms of drainage and rigidity of the block 20.

Here, if the groove depth is less than 8 mm and the groove width is less than 3 mm, it is not preferable because the drainage property of the groove cannot be sufficiently exhibited. If the negative ratio is less than 25%, the drainage property is deteriorated, which is not preferable.
When it is higher than%, the block 20 as the ground contact land portion becomes small and the rigidity is lowered, so that the braking performance / driving performance may be deteriorated and the abrasion resistance performance is deteriorated, which is not preferable.

A sipe 22 extending in the tire width direction (arrow W direction) is provided on the tread surface of these blocks 20.

Further, a fine rib 26 is provided on the tread surface of the block 20. The fine ribs 26 of the present embodiment extend along the tire circumferential direction and are arranged in parallel in the tire width direction at predetermined intervals over the entire tread surface of the block 20,
Further, they are arranged in all blocks 20.

As shown in FIG. 2, the fine ribs 2 of this embodiment are shown.
No. 6 has a substantially rectangular cross section, and as shown in FIG. 3, the height H is 30 μm, the width W of the top is 150 μm, and the interval T between the adjacent fine ribs 26 is 100 μm. The side surface 26A of the fine rib 26 has the pneumatic tire 10
It is tapered so that it can be easily removed from the mold.

Here, the height H of the fine ribs 26 is from 5 μm to
1.0 mm, preferably 20 μm to 300 μm,
The width W of the top is 5 μm to 2.0 mm, preferably 20 μm
~ 1.5 mm. Further, the interval T between the adjacent fine ribs 26 is 5 μm to 1.5 mm, preferably 10 μm to
It is 1.0 mm.

If the height H is less than 5 μm, water generated between the ice surface and the ice surface cannot be sufficiently discharged, which is not preferable, and when the height H is more than 1.0 mm, the pneumatic tire 10 is molded. This is not preferable because the mold cleaning property deteriorates, and the rigidity of the tread surface decreases too much when traveling on a dry road surface, resulting in a decrease in exercise performance.

Further, if the interval T is less than 5 μm, it is not preferable because water generated between the ice surface and the ice surface cannot be sufficiently discharged, and if it exceeds 1.5 mm, it is formed by the fine ribs 26 during running or braking. It is not preferable because the groove formed may be crushed and the initial effect cannot be obtained.

Further, if the width W of the top portion is less than 5 μm, the fine grooves are crushed and the drainage effect cannot be obtained, which is not preferable, and if it exceeds 2.0 mm, the number of the fine groove portions becomes too small and the drainage effect is obtained. Is not preferable because it is impossible to obtain

Here, the traction edge component density (TED) [= T.Total Ed of the pneumatic tire 10 of the present example.
ge / {(1-Neg.Ratio) ・ Contact WD}. However, T.To
talEdge; the sum of the components in the width direction (projection length on the plane perpendicular to the tire equatorial plane) of the edge of the ground contact tread (block 20 in this embodiment) within one pattern pitch, and the distribution to the ground contact tread. A value obtained by dividing the total sum of the widthwise components of the sipe to be installed by the pitch length. Neg.Ratio ； Negative ratio of tread tread. Contact WD: The ground contact width when mounted on a regular rim, filled with regular internal pressure, and subjected to regular load. ] Is
It is 0.21 (1 / mm).

This traction edge component density is 0.
It is preferably 15 to 0.25 (1 / mm).

The traction edge component density is 0.15 (1
If it is less than / mm), the edge component will be insufficient and braking performance and driving performance on ice and snow road surface will be inferior, and if it is more than 0.25 (1 / mm), the rigidity of the block 20 will be lowered too much and abrasion resistance It is not preferable for steering stability.

The traction edge component here does not include fine grooves. The fine ribs 26 are formed on the inner surface of the mold for vulcanizing the pneumatic tire 10 by cutting,
It can be obtained by forming fine grooves by electric discharge machining, etching, or the like.

The fine ribs 26 are formed on the tire after molding,
It can also be formed into a tire whose surface has been worn to some extent due to running, and in such a tire, the fine ribs 26 can be obtained by forming fine grooves by surface buffing by knife cutting or sandpaper. it can.

Next, the operation of the pneumatic tire 10 of this embodiment will be described. When the pneumatic tire 10 travels on an ice / snow road, water is generated due to pressure and friction when the tread 12 and ice or snow come into contact with each other. This water that causes a decrease in frictional force is generated by the fine ribs 2 provided on the tread surface of the block 20.
6 is taken into the fine groove portion and discharged through the groove portion to the circumferential grooves 14 and 16 and the lateral groove 18,
The water film between the tread and the road is removed.

Therefore, the pneumatic tire 10 of this embodiment is
Compared with a tire in which the fine ribs 26 are not formed on the tread surface, braking performance / driving performance on ice and snow road surfaces is improved, and even on wet road surfaces, the drainage effect of the groove portion between the fine ribs 26 results in a wet condition. Performance is improved. That is, the present invention can be applied to tires other than studless tires.

Furthermore, as a studless tire, when forming closed cells in the tread by mixing a foaming agent into the rubber material of the tread, closed cells are less likely to be formed on the surface of the tread which was in contact with the vulcanization mold. Since a smooth skin layer is formed (not shown), it is difficult to obtain sufficient on-ice performance in the initial stage of use as compared with a tire in which closed cells are exposed on the surface, but according to the present invention, running-in running By doing so, this point can be covered without removing the skin layer.

[Second Embodiment] FIG. 4 shows a second embodiment of the present invention.
And it demonstrates according to FIG. It should be noted that this embodiment is a modification of the first embodiment, and the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 4 and 5, the block 20 of the pneumatic tire 10 of this embodiment is provided with lateral fine auxiliary grooves 28 for increasing the amount of water taken in.

As shown in FIG. 5, lateral fine auxiliary grooves 28 are formed.
Extend in the tire width direction so as to cross the fine ribs 26, and both ends are open to the side walls of the fine ribs 26.

The lateral fine auxiliary grooves 28 are arranged at predetermined intervals in the circumferential direction, and are different from the lateral fine auxiliary grooves 28 formed on the fine ribs 26 adjacent to each other in the tire width direction (arrow W direction). , Are arranged with a phase difference in the circumferential direction. The lateral fine auxiliary groove 28 of this embodiment has a groove width w of 0.
1 mm, groove depth 30 μm, circumferential pitch P
Is 1.0 mm.

Since at least one end of the lateral fine auxiliary groove 28 is open to the side wall of the fine rib 26, water can be taken in, so that both ends do not necessarily have to be opened to the side wall of the fine rib 26. . In addition, the lateral fine auxiliary groove 28
Need only extend in the direction intersecting the fine ribs 26, and need not necessarily extend in the tire width direction.

In the pneumatic tire 10 of this embodiment, the provision of the lateral fine auxiliary grooves 28 makes it possible to more effectively take in water and more reliably remove the water film. Further, since the lateral fine auxiliary grooves 28 are arranged adjacent to each other in the tire width direction with a phase difference in the circumferential direction, the amount of water taken into each lateral fine auxiliary groove 28 is averaged, And the water intake is most effective. As a result, braking performance / driving performance on a snowy and snowy road surface is further improved.

The preferable range of the groove width w of the lateral fine auxiliary groove 28 is 5 μm to 1.5 mm, and the preferable range of the groove depth of the lateral fine auxiliary groove 28 is 5 μm to 1.0 mm.
Is. When the groove width w of the lateral fine auxiliary groove 28 is less than 5 μm, the effect of taking in water is reduced, which is not preferable, and when it exceeds 1.0 mm, the exercise performance on a dry road surface is deteriorated, which is not preferable.

Further, the lateral fine auxiliary groove 28 has a groove depth of 5
When the thickness is less than μm, the amount of water taken in decreases, and the effect of providing the lateral fine auxiliary groove 28 is lost. On the other hand, if the groove depth exceeds 1.0 mm, the cleaning property of the vulcanizing mold for molding the pneumatic tire 10 and the exercise performance on a dry road surface are deteriorated, which is not preferable.

Further, the circumferential pitch P of the lateral fine auxiliary grooves 28 in the circumferential direction is preferably 5 μm to 1.5 mm. The circumferential arrangement pitch P of the lateral fine auxiliary grooves 28 is 5μ.
If it is less than m, the length of one fine rib 26 becomes too short and the rigidity of the fine rib 26 decreases, which is not preferable. On the other hand, if the pitch P in the circumferential direction exceeds 1.5 mm, the amount of water taken in decreases and the effect of providing the lateral fine auxiliary grooves 28 disappears.

[Third Embodiment] FIG. 6 shows a third embodiment of the present invention.
Follow the instructions below.

As shown in FIG. 6, the tread 12 of the pneumatic tire 10 of this embodiment is provided with three circumferential grooves 30 extending linearly in the tire circumferential direction, one of which is the tire equatorial plane CL. The other two are arranged at predetermined intervals on both sides of the tire equatorial plane CL in the width direction.

The left tread 12 with the tire equatorial plane CL as a boundary is provided with a straight lateral groove 32 which inclines to the right with respect to the tire width direction at a predetermined angle. Tread 12 on the right
In the tire, straight lateral grooves 32 that are inclined at a predetermined angle to the left with respect to the tire width direction are arranged symmetrically with respect to the tire equatorial plane CL. On the tread 12, a plurality of parallelogram-shaped blocks 20 defined by the circumferential grooves 30 and the lateral grooves 32 are formed.

In each block 20, fine ribs 26, which are inclined at an angle θ when measured from the acute angle side with respect to the tire circumferential direction (direction of arrow S), are formed in parallel with each other at predetermined intervals. Block 20 on the left side of the tire equatorial plane CL as a boundary
The fine ribs 26 formed on the right angle with the tire circumferential direction are inclined at an angle θ, and the fine ribs 26 formed on the right block 20 with the tire equatorial plane CL as a boundary are formed in the tire circumferential direction. Tilts to the left at an angle θ,
When viewed as the entire tread pattern, the fine ribs 26 are arranged substantially in a V shape on both sides of the tire equatorial plane CL.

Further, in each block 20, sipes 22 extending in the tire width direction are formed on both sides in the tire width direction.

In the pneumatic tire 10 shown in FIG. 6 as well, the action of the fine ribs 26 improves the braking performance / driving performance on the snow and snow road surface and the wet road surface.

When the tire is directional, the fine ribs 26 are arranged substantially in a V shape on both sides of the tire equatorial plane CL when viewed as the entire tread pattern, as shown in FIG. Alternatively, the fine ribs 26 may be tilted in the direction opposite to the direction shown in FIG. 6 and arranged so as to have an inverted V shape. Further, as shown in FIG. 7, a plurality of fine ribs 26 may be arranged in parallel so as to form an inverted V shape or a C shape in one block row, and sandwich the tire equatorial plane CL. There may be a slight phase difference in the tire circumferential direction when the two sides are compared with each other.

Further, the fine ribs 26 may be inclined in the same direction in one block row extending in the circumferential direction as shown in FIG.
It may be inclined in the opposite direction.

It should be noted that the inclination angle θ of the fine ribs 26 does not necessarily have to be constant in all the blocks 20, and the angles may be varied between the block rows, for example, as shown in FIG.
When there are 6 block rows, the inclination angle of the fine ribs 26 of the block row on the tire equatorial plane CL side is θ.
1. The fine ribs 26 in the block row on the outer side in the tire width direction
Where θ2 is the inclination angle and θ3 is the inclination angle of the fine ribs 26 of the outermost block in the tire width direction, θ1 <θ
2 <θ3 may be set.

When the fine ribs 26 are inclined with respect to the tire circumferential direction, the angle θ of the fine ribs 26 measured from the acute angle side is preferably within the range of 0 ° to 40 °.

Further, as shown in FIG. 9, the angle θ of the fine ribs 26 may be substantially continuously changed within the range of 0 ° to 40 ° within one block 20, and may be changed stepwise. You can do it. Further, most of the fine ribs 26 are effective if they are inclined at a relatively small angle with respect to the tire circumferential direction, and the shape thereof may be any shape.

If the angle .theta. Of the fine ribs 26 with respect to the tire circumferential direction exceeds 40.degree., The drainage effect of the grooves formed between the ribs 26 decreases, which is not preferable. Therefore, the angle is set to a relatively small angle of 40 ° or less.

Further, the fine ribs 26 are formed in one block 2
Besides arranging them in parallel within 0, they may be arranged in a cross shape as shown in FIG.

Further, as shown in FIG. 11, it goes without saying that the fine ribs 26 may be arranged so as to be inclined with respect to the tire circumferential direction, and the lateral fine auxiliary grooves 28 may be provided.

[Fourth Embodiment] A fourth embodiment of the present invention is shown in FIG.
It will be explained according to 2.

As shown in FIG. 12, in the pneumatic tire 10 of the present embodiment, the tread 12 has a base rubber layer 34 arranged on the inner side in the tire radial direction, and on the outer side of the tire radius of the base rubber layer 34 during running. An intermediate rubber layer 36 that constitutes the main component to be provided is arranged, and further, a covering rubber layer 38 is arranged outside the intermediate rubber layer 36 in the tire radius.

The covering rubber layer 38 is the adjacent intermediate rubber layer 3
The rubber composition of No. 6 is different from that of No. 6, and the thickness thereof is in the range of 0.3 to 1.0 mm.

The hardness (JIS-A) of the coated rubber layer 38 is
It is preferably smaller than that of the intermediate rubber layer 36, more preferably 5 to 20 degrees.

This is for avoiding manufacturing defects such as generation of bares due to rubber flow defects during tire vulcanization. That is, the rubber needs to follow the vulcanizing mold forming the fine ribs 26, and the soft rubber is arranged as the covering rubber layer.

If the thickness is less than 0.3 mm, the volume may be insufficient and manufacturing defects may be unavoidable. On the other hand, if it exceeds 1.0 mm, it takes time to expose the intermediate rubber layer 36, and the initial exercise performance may be deteriorated. There is concern and it is not preferable.

Similarly, the hardness is made smaller than the intermediate rubber layer 36 by 5 degrees or more in order to avoid manufacturing defects, and is made smaller in the range of 20 degrees or less in order to maintain the braking / driving performance on the dry road / wet road. It is preferable.

The coating rubber layer 38 may be added with a third component of an organic and / or inorganic substance having a hardness higher than that of rubber in order to increase the frictional force on the road surface. Specific examples of the third component include walnut shell powder, polyamide short fibers, and fine powder of resin and the like. When the third component has a long shape such as a fiber, it is preferable that its main direction be substantially parallel to the tire circumferential direction.

By adding the third component of the organic and / or inorganic substance, the braking / driving performance in the initial stage on the snow and snow road can be enhanced. When the third component is a long shape such as a fiber and is oriented in the tire circumferential direction, fine ribs can be formed thereby, and the drainage effect at the initial stage of wear can be enhanced.

As the intermediate rubber layer 36, a foamed rubber layer or a rubber to which a third component of organic and / or inorganic substance is added may be used.

(Test Example 1) In order to investigate the effect of the present invention, Example tire A to which the present invention was applied (the pneumatic tire of the first example shown in FIG. 1) and Example tire B (see FIG. 4) Pneumatic tire of the second example shown) and conventional tire A without fine ribs (pneumatic tire of the first example shown in FIG. 1 from which the fine ribs are removed), a total of three types of pneumatic tires (tires). Size 195 / 65R15, internal pressure 2.0kg
/ cm ² )) was prepared and the test was carried out for each item of grip level, controllability, braking distance on dry snow road (ice burn), dry performance on general road, and wet performance. The test is carried out by mounting a test tire on a passenger car having a displacement of 1500 cc, and the test methods and test conditions are as shown below. In addition, the test result shows the tire A of the conventional example.
Is shown as an index in Table 1 below.

Test method and test conditions Grip level on a snow-packed road: snow-packed road (in an ice-burn state, air temperature -7 ° to -10 ° C, road surface temperature -6 ° to-)
Evaluated according to the feeling of the test driver after running at 10 ° C. The larger the value, the higher the grip level.

Controllability on a snow-covered road: The handling performance when running on a snow-covered road was evaluated by the feeling of a test driver. The higher the value, the better the controllability.

Braking distance on a snowy road: The braking distance was measured. The smaller the value, the shorter the braking distance.

Dry performance on general road: Steering stability was evaluated by the feeling of a test driver. The larger the number, the better the dry performance.

Wet performance on a general road: The steering stability of a wet road (water depth 2.0 mm) was evaluated by the feeling of a test driver. The larger the value, the better the wet performance.

[0077]

[Table 1]

(Test Example 2) Further, in order to investigate the effect of the present invention in the same manner as in Test Example 1, the example tire C to which the present invention was applied (the pneumatic tire of the third example shown in FIG. 6). , Example tire D (the pneumatic tire of the example shown in FIG. 11) and conventional tire B without fine ribs (the pneumatic tire of the third example shown in FIG. 6 from which the fine ribs have been removed), a total of 3 Seed pneumatic tire (tire size 195
/ 65R15, internal pressure 2.0 kg / cm ² ) was prepared, and the same test as in Test Example 1 was performed.

The test results are shown in Table 2 below as an index with the conventional tire B being 100.

[0080]

[Table 2]

From the test results shown in Tables 1 and 2 above, the pneumatic tires according to the present invention (Example tires A, B,
It is clear that C and D) have improved performance on a snow-covered road and wet performance on a general road without deteriorating other performances.

[0082]

As described above, the pneumatic tire of the present invention takes in water, which causes a reduction in frictional force, in the groove portions between the fine ribs, and through the groove portions to the outside of the ground contact land portion. Therefore, the braking performance and the driving performance are improved on the ice and snow road surface or the wet road surface, and the overall performance as a pneumatic tire is improved, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a plan view of a tread of a pneumatic tire according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of the block shown in FIG.

FIG. 3 is an enlarged cross-sectional view of a minute rib shown by an arrow A in FIG.

FIG. 4 is a plan view of a tread of a pneumatic tire according to a second embodiment of the present invention.

5 is an enlarged plan view of the block shown in FIG.

FIG. 6 is a plan view of a tread of a pneumatic tire according to a third embodiment of the present invention.

FIG. 7 is a plan view of a tread of a pneumatic tire according to another embodiment of the present invention.

FIG. 8 is a plan view of a tread of a pneumatic tire according to still another embodiment of the present invention.

FIG. 9 is a plan view of a tread of a pneumatic tire according to still another embodiment of the present invention.

FIG. 10 is a plan view of a tread of a pneumatic tire according to still another embodiment of the present invention.

FIG. 11 is a plan view of a tread of a pneumatic tire according to still another embodiment of the present invention.

FIG. 12 is a sectional view of a block of a pneumatic tire according to a fourth embodiment of the present invention.

[Explanation of symbols]

 10 Pneumatic tire 12 Tread 20 Block 26 Fine rib

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kojima 4-19-5 Higashi Toyota, Hino City, Tokyo (72) Inventor Ryuji Izumimoto 3-5-5 Ogawa Higashimachi, Kodaira-shi, Tokyo (72) Inventor Moji Kaji Shiro 728-4 Ishihata, Mizuho-cho, Nishitama-gun, Tokyo

Claims (2)

[Claims] 1. In a pneumatic tire having a tread pattern, fine ribs having an angle between the longitudinal direction and the tire circumferential direction in the range of 0 ° to 40 ° are arranged in the tire width direction on the ground contact land portion of the tread. A pneumatic tire characterized by being installed. 2. The fine ribs have a top width of 5 μm to
The pneumatic tire according to claim 1, wherein the pneumatic tire has a height of 2.0 mm, a height of 5 μm to 1.0 mm, and an interval between adjacent fine ribs of 5 μm to 1.5 mm.