JPH11342706A - Pneumatic tire for show-icy road - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve both of icy performance and dry turning performance as suppressing drop in snowy performance. SOLUTION: In this tire, two blocks 4 are merely formed in an inner tread surface area 1 at the tire vehicle attached inside from a tire center line CL, while a plurality of ribs 5 extending in the tire circumferential direction are set up in an outer tread surface area at the tire vehicle attached outside. A groove area ratio of the inner tread surface area 1 is 45±15% to an area of the area 1, and a groove area ratio of the outer tread surface area O is 25±15% of the area O, and the groove area ratio of the inner tread surface area 1 is made larger by 5% or more than the outer tread surface area O.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for use on icy and snowy roads, and more particularly to a pneumatic tire for use on icy and snowy roads in which both the on-ice performance and the dry turning performance are greatly improved while suppressing a decrease in on-snow performance. Related to pneumatic tires.

[0002]

2. Description of the Related Art Generally, a pneumatic tire for icy and snowy roads is shown in FIG.
As shown in FIG. 1, a large number of blocks 14 are defined on a tread surface 11 by a main groove 12 extending in the tire circumferential direction T and a lug groove 13 extending in the tire width direction, and a sipe extending in the tire width direction is formed on the surface of the block 14. 15 is formed. Further, a low hardness rubber is used for the tread portion. The main groove 12 and the lug groove 13 secure the groove area to exhibit high performance on snow, while the edge effect of the block 14 and the sipe 15 and the grounding effect of the tread portion made of low hardness rubber ensure the performance on ice. ing.

[0003] However, since the tread surface is subdivided into blocks and low-hardness rubber is used for the tread portion, there has been a problem that turning performance on a dry road surface is reduced. In recent years, in cold regions such as Hokkaido, the road surface often freezes in winter and causes the Millerburn phenomenon. Therefore, further improvement in performance on ice has been required. Therefore, as a countermeasure, as shown in FIG.
There is proposed a technique in which a rib 16 is divided by a main groove 12 extending in a tire circumferential direction T, and a sipe 15 extending in the tire width direction is formed on the surface of the rib 16. By providing a rib pattern on the tread surface 11, a large contact area is ensured, the performance on ice is greatly improved, and the turning performance on a dry road surface is also greatly improved. However, the adoption of such a rib pattern inevitably reduces the groove area, and there is a problem that the performance on snow greatly deteriorates.

[0004] Further, as shown in FIG.
Ribs 16 are arranged on both sides of the center of the
There is also a proposal for a technology provided with 4. By arranging the ribs 16 and the blocks 14 in a mixed manner as described above, a relatively large ground contact area can be ensured with respect to the block pattern of FIG. While the performance on ice has been greatly improved. However, the effect of improving the turning performance on dry road surfaces was small, and was not satisfactory.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire for snowy and snowy roads capable of greatly improving both on-ice performance and dry turning performance while suppressing a decrease in on-snow performance. .

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a plurality of main grooves extending in a tire circumferential direction on a tread surface. Are arranged at a predetermined pitch in the tire circumferential direction to form only a land portion composed of a block defined by the main groove and the lug groove, while the main area of the outer tread surface area outside the tire vehicle mounting is formed. Forming a land portion comprising a plurality of ribs extending in the circumferential direction of the tire divided by the main groove, providing a sipe extending in the tire width direction on the land portion formed on the tread surface, and forming a groove in the inner tread surface region. The area ratio is 45 ± 15% with respect to the area of the tread surface region, and the groove area ratio in the outer tread surface region is 25% with respect to the area of the tread surface region.
The inner tread surface area is set to ± 15%, and the groove area ratio of the inner tread surface area is made 5% or more larger than that of the outer tread surface area.

As described above, while maintaining the groove area ratio of the inner tread surface region on the tire vehicle inner side to the outer tread surface region on the tire vehicle outer side within the above range, the tread surface has a block and rib with a sipe. By providing both, compared to the conventional pneumatic tire for icy and snowy roads provided with a block pattern, it is possible to secure a wider contact area and prevent a large decrease in groove area, so that the performance on snow decreases. The performance on ice can be greatly improved while suppressing the noise. Further, by providing only the blocks in the inner tread surface region and disposing the ribs in the outer tread surface region, it is possible to increase the dread stiffness on the outer side of the tire mounted on the tire vehicle, which greatly affects turning on a dry road surface. Even when a low hardness rubber is used for the tread portion, the dry turning property can be greatly improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be specifically described below with reference to the embodiment shown in the drawings. FIG. 1 shows an example of a main part of a tread surface of a pneumatic tire for icy and snowy roads according to the present invention. In a tread surface 1, a plurality of main grooves 2 extending straight in a tire circumferential direction T are provided. . One main groove 2A having a wider groove width is disposed on the tire center line CL, and main grooves 2B having a groove width narrower than the main groove 2A are disposed on the left and right sides.

On the right inner tread surface region I, which is inside the mounting of the tire vehicle, with respect to the tire center line CL,
The lug grooves 3 extending in the tire width direction are arranged at a predetermined pitch in the tire circumferential direction T, and the main groove 2 and the lug grooves 3 define a block (land portion) 4.

In the main area Oa of the left outer tread surface area O on the outer side of the tire vehicle mounting, three main grooves 2A, 2
Two ribs (land portions) 5 extending straight in the tire circumferential direction T divided by B and 2B are formed. On the tread surface 1 on the shoulder side of the main region Oa, lug grooves 6 extending in the tire width direction are arranged at a predetermined pitch in the tire circumferential direction T, and a block (land portion) 7 is formed by the main groove 2B and the lug grooves 6. A section is formed, and an asymmetric tread pattern is formed on the tread surface 1. Here, the main area Oa means a range from the tire center line CL to the tire contact edge E of the outer tread surface area O in the range from the tire center line CL to the tire contact edge E side, up to 90% in the tire width direction. Area. Tire contact edge E
JATMA YEAR BOOK is the tire entry column in the pneumatic-load capacity correspondence table of 1998. If there is a distinction between S and D, the entry is in the S column. Means the tire contact end when the maximum load is applied under the air pressure condition corresponding to the maximum load capacity.

The groove area ratio of the inner tread surface region I is in a range of 45 ± 15% with respect to the area of the region I.
The groove area ratio of the outer tread surface region O is in a range of 25 ± 15% with respect to the area of the region O. Further, the groove area ratio of the inner tread surface region I is set to be 5% or more larger than the groove area ratio of the outer tread surface region O.

A plurality of sipes 8 extending straight in the tire width direction are provided on the surfaces of the blocks 4 and 7 and the ribs 5 so as to communicate with the main groove 2. Also, a tread portion X in which blocks or ribs are provided on the tread surface 1
Is made of low hardness rubber having a JIS A hardness of 45 to 60.

As described above, according to the present invention, while the groove area ratio between the inner tread surface region I and the outer tread surface region O is maintained in the above-described range, the block having the sipe 8 on the tread surface 1 and the rib are mixed. By arranging them, the ground area can be secured more than the conventional block pattern,
Since the decrease in the groove area can be suppressed, the decrease in the performance on snow can be suppressed, and the performance on ice can be greatly improved. On the other hand, only the block 4 is arranged in the inner tread surface region I which is the tire vehicle mounting inner side, By providing the ribs 5 in the outer tread surface region O on the outer side of the tire vehicle, the dread stiffness on the outer side of the tire vehicle, which greatly affects turning on a dry road surface, can be increased. Even when rubber is used, it is possible to effectively improve dry turning performance.

In the embodiment of the present invention, two ribs 5 are provided in the main region Oa of the outer tread surface region O. However, the number of ribs may be one to five. Further, the main groove 2 may be formed in a zigzag shape instead of the straight shape, and the rib 5 may meander in a zigzag shape.

The present invention can be suitably used particularly for a pneumatic radial tire for snowy roads using a low hardness rubber in the tread portion, but is a pneumatic tire for snowy roads in which the tread portion is not formed of low hardness rubber. You may.

[0016]

Example 1 A tire 1 of the present invention having a tread pattern shown in FIG. 1 and a tread pattern shown in FIGS. 2 and 3 using a tire size common to 265 / 70R16 and using a low hardness rubber for a tread portion was used. Conventional tires 1 and 2 were produced.

Each of these test tires was rim size 16 × 7.
Attach it to the JJ rim, set the air pressure to 200 kPa, and
When mounted on a 0 cc vehicle and subjected to evaluation tests on ice performance, snow performance and dry turning performance under the following measurement conditions, the results shown in Table 1 were obtained.

On-ice performance On a icy road test course with an ice temperature of -5 ° C. to -8 ° C. and an air temperature of -3 ° C. to -5 ° C., the linear braking distance when braking from a speed of 40 km was measured, and the results were used in the invention. The tire 1 was evaluated with an index value of 100. The larger the value, the better the performance on ice.

On-snow performance A feeling test was conducted by a panelist on a snowy road test course at a snow temperature of -3 ° C to -6 ° C and an air temperature of -2 ° C to -5 ° C. It was evaluated by an index value. The larger the value, the better the performance on snow.

Dry turning performance On a dry circuit road surface, a feeling test was performed by a paneler at the time of cornering, and the result was evaluated by an index value with the tire 1 of the present invention as 100. The larger the value, the better the dry turning performance.

[0021]

[Table 1]

From Table 1, it can be seen that the tire of the present invention is the same as the conventional tire 2
On the other hand, it can be seen that both the on-ice performance and the dry turning performance can be greatly improved while suppressing the decrease in the on-snow performance.

Example 2 The tire 1 of the present invention, the tire 2 of the present invention having the same tire size as that of Example 1, and the groove area ratio was changed as shown in Table 2, the comparative tires 1 to 8, and the tread of FIG. A conventional tire 3 having a pattern was manufactured. Note that the present tire 2 and the conventional tire 3 have the same total groove area ratio.

Each of the test tires was subjected to evaluation tests on ice performance, snow performance and dry turning performance in the same manner as in Example 1, and the results shown in Table 2 were obtained. However, in Table 2, the evaluation was made with an index value with the conventional tire 3 being 100.

[0025]

[Table 2]

From Table 2, the groove area ratio of the inner tread surface region is 45 ± 15%, and the groove area ratio of the outer tread surface region is 25%.
The tire 2 of the present invention in which the groove area ratio of the inner tread surface region is set to be within ± 15% and the groove area ratio of the inner tread surface region is 5% or more larger than that of the outer tread surface region has improved the performance on ice while suppressing the decrease in the performance on snow. It can be seen that the dry turning performance can be further improved compared to the conventional tire 3.

The groove area ratio between the inside and outside of the conventional tire 3 is 20% and 20%, 30% and 30%, 40% and 40%.
%, 50% and 50%, and correspondingly the inner and outer groove area ratios are 10% and 30%, 20% and 40%, 30% and 50%.
%, 40% and 60% of the tires of the present invention, and comparative tires in which the ratios were changed out of the range as shown in Table 2 above, and evaluation tests of each test tire were performed in the same manner as above. As a result, a result showing the same tendency as the result shown in Table 2 was obtained.

[0028]

As described above, the pneumatic tire for icy and snowy roads of the present invention has only the block formed in the inner tread surface area inside the tire vehicle, and the tire circumferential direction in the outer tread surface area outside the tire vehicle. By arranging a plurality of ribs extending in the range and setting the groove area ratio in the above range, it is possible to greatly improve both the on-ice performance and the dry turning performance while suppressing the decrease in the on-snow performance.

[Brief description of the drawings]

FIG. 1 is a development view of a main portion of a tread surface showing an example of a pneumatic tire for icy and snowy roads according to the present invention.

FIG. 2 is a development view of a main portion of a tread surface showing an example of a conventional pneumatic tire for snowy and snowy roads.

FIG. 3 is a development view of a main part of a tread surface showing another example of a conventional pneumatic tire for snowy roads.

FIG. 4 is a development view of a main portion of a tread surface showing still another example of a conventional pneumatic tire for snowy roads.

[Explanation of symbols]

1 Tread surface 2, 2A, 2B
Main groove 3, 6 Lug groove 4, 7 Block 5 Rib 8 Sipe CL Tire center line I Inner tread surface region O Outer tread surface region Oa Main region T Tire circumferential direction X Tread portion

Claims (4)

[Claims] A plurality of main grooves extending in a tire circumferential direction are provided on a tread surface, and lug grooves extending in a tire width direction from a tire center line to an inner tread surface area inside a tire vehicle are mounted at a predetermined pitch in a tire circumferential direction. The main groove and the lug groove are arranged so as to form only a land portion composed of a block defined by the main groove and the tire extends in the tire circumferential direction divided by the main groove in a main region of an outer tread surface region outside the tire vehicle mounting area. A land portion made of ribs is formed, a sipe extending in the tire width direction is provided on the land portion formed on the tread surface, and a groove area ratio in the inner tread surface region is set to 45 ± 15% with respect to an area of the tread surface region. The groove area ratio in the outer tread surface area to the area of the tread surface area by 2
A pneumatic tire for icy and snowy roads, which has a groove area ratio of 5 ± 15% and a groove area ratio of the inner tread surface region that is at least 5% larger than that of the outer tread surface region. 2. A main region of the outer tread surface region includes:
2. The pneumatic tire for snowy and snowy roads according to claim 1, wherein a range from the tire center line to the tire contact end is 90% from the tire center line to the tire contact end. 3. 3. The pneumatic tire for icy and snowy roads according to claim 2, wherein 1 to 5 land portions made of the ribs are provided. 4. The rubber portion of the tread portion has a JIS A hardness of 45.
The pneumatic tire for icy and snowy roads according to claim 1, 2, 3 or 4, wherein the pneumatic tire is made of a low-hardness rubber of from 60 to 60.