JPH03125608A - Snow tire - Google Patents

Abstract

PURPOSE:To improve sucking force, i.e. gripping force of holes at the time of traveling on an ice and snow road or the like by providing a proper number of holes which extends from the surface of blocks to the center of a tire and which has a diameter within the specified values on each block of a tread pattern. CONSTITUTION:A snow tire is provided with tread patterns 22 having a large number of blocks 24 formed by a large number of grooves 12, 14, 16, 18, 20 crossing each other. In the above structure, each block 24 is provided with a large number of holes 26 corresponding to the size of each block 24. Each hole 26 is formed in a circular cross section each having given diameter and also a limit position functioning as a snow tire, i.e. depth from the surface of the tread position to a platform is ensured. At this time, the abovementioned diameter (d) is set within the limits of 5-10mm. Sucking force, i.e. gripping force due to each hole 26 is improved at the time of traveling on an ice and snow road without lowering the rigidity of each block 24.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to snow tires, and more particularly to snow tires having a tread pattern that includes a plurality of blocks separated from each other by grooves.

(Prior Art) Spiked tires are one type of snow tires for use on icy roads, snow-covered roads, and the like. This spiked tire is used as a snow tire by driving spikes or studs into each of a plurality of holes formed in the tread.

However, spiked tires have problems such as noise, dust, and road damage.

Another type of snow tire is a perforated tire.

However, conventional perforated tires cannot be used as studless snow tires because the holes are only formed in a portion of the shoulder, and the adhesion to icy or snowy roads is small.

(Problems to be Solved) An object of the present invention is to provide a studless snow tire that has a high suction force, that is, a grip force due to the holes when driving on an icy road, a snowy road, etc.

(Solution, Operation, Effect) The snow tire of the present invention has a tread pattern including a plurality of blocks separated from each other by grooves, each block having at least one hole extending from its surface toward the center of the tire. and each person has a diameter dimension of 5 mm or more and 10 mm or less.

Each has the effect of increasing grip power when driving on icy roads, snowy roads, etc. When the diameter of the hole is less than 5 mm, the gripping force decreases rapidly. On the other hand, each person's diameter is f
If it exceeds Omm, the rigidity of the block will drop sharply, resulting in a sharp drop in driving force and wear resistance.

According to the snow tire of the present invention, since each block has a hole of a predetermined diameter, the grip force when driving on icy roads, snow-covered roads, etc. is large without causing a decrease in the rigidity of the blocks. In other words, there is no need to use studs.

The depth of the hole can be the same as the distance from the surface of the block to the limit position or platform that indicates the function as a snow tire.

The tread rubber of the tire is a compound, and has a glass transition point Tg of -50 degrees C or lower -60 degrees C or higher.
and HD according to JIS standard at -5 degrees C.
60 or less) preferably has a hardness of 1072 or less.

When the glass transition point of the tread rubber is less than 160 degrees Celsius, the physical properties of the rubber deteriorate and the tear resistance decreases. If the glass transition point of the tread rubber exceeds 150 degrees, the on-snow performance will drop sharply, depending on the hardness of the tread rubber.

If the hardness of the tread rubber is less than HD60, the wear resistance on the ship will be reduced. Tread rubber hardness is HD72
If it exceeds this, the tread will not have sufficient adaptability or tracking ability to the unevenness of the road surface, resulting in poor performance on ice and snow.

The number of holes in each block can be two or more. Also,
The snow tire of the present invention can be a snow tire as defined by the National Rubber Industry.

(Example) The snow tire lO shown in FIGS. 1 and 2 has a plurality of first grooves 12 extending in the circumferential direction of the tire, and a curved surface outward in the width direction of the tire from the first grooves. A plurality of second grooves 14 that extend and are separated from each other in the circumferential direction of the tire, a plurality of third grooves 16 that make adjacent second grooves 14 communicate with each other, and a plurality of third grooves 16 that make first grooves 12 communicate with each other. 4 grooves 18 and a fifth groove 20 that connects the fourth grooves 18 with each other,
It has a tread pattern 22 shown in FIG. The tread pattern 22 may have a shape other than that shown in FIG. 2.

Each block 24 separated by grooves 12-20 has a plurality of holes 26 formed therein depending on the size of the block. Each person 26 has a circular cross-sectional shape with a diameter d, and a depth t from the surface of the tread portion 28 to the limit position or platform 30 functioning as a snow tire.
has. Each block 24 defines a ground contact surface of the tread portion 28.

The diameter d is preferably 5 mm or more and 10 mm or less. The diameter d of the holes may be the same or different. However, it is preferable that the sizes d, t, and number of the holes 26 in each block 24 are set to values that will make the installation shape of the block as flat as possible and the installation pressure distribution uniform.

The depth of the groove 12.16 is slightly larger than the depth t of the hole 26;
The depth of the grooves 14,18 is approximately the same as the depth t of the hole 26, and the depth of the groove 20 is less than the depth t of the hole 26.

The tread rubber is a compound, and has a glass transition point Tg of -50 degrees C or lower and -60 degrees C or higher, and HD60 or lower according to JIS standards at -5 degrees C.
It is preferable to have a hardness of HD72 or less.

(Experiment example) A braking test on ice to determine the locking braking distance from 30 km/h on a conventional spiked tire A, a tire B of the present invention, and a conventional studless snow tire C without spikes, at a slope of 8%. A climbing test on ice to determine the distance reached at a constant initial speed on a water boarding road and a wear resistance test were conducted using a front-wheel drive passenger car. The test results are shown in Table 1.

The tread pattern of tire B is the pattern shown in FIG.
As shown in FIG. 2, the number of holes 26 was 2 to 5 depending on the size of the block 24, the hardness of the tread portion 24 was HD63, and the glass transition point Tg of the tread rubber was -56. Tire A
.

The sizes of B and C were 165R13.

The performance shown in Table 1 is expressed as an index when spiked tire A is set as 100, and the larger the value, the better.

1. As is clear from Table 1, although the tire B of the present invention is slightly inferior to the conventional spiked tire A in terms of ice braking, ice pitching, and abrasion resistance, it is still superior in ice braking and ice pitching. Superior to conventional studless snow tires C.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the tire of the present invention, and FIG.
1 is a diagram showing a tread pattern of the tire shown in FIG. 1. FIG. lO tires! 2, 14, 16, 18, 20: Groove. 22 Nidred pattern, 24 Niblock, 26 holes, 28 Tread section, 30 Nibrat home.

Claims (4)

[Claims] (1) An automobile snow tire having a tread pattern including a plurality of blocks separated from each other by grooves, each block having at least one hole extending from its surface toward the center of the tire, each hole is 5mm or more1
Snow tires with a diameter of 0 mm or less. (2) The snow tire according to claim 1, wherein the depth of the hole is the same as the distance from the surface of the block to the platform. (3) The tread rubber of the tire is a compound, and has a glass transition point Tg of -50 degrees C or lower and -60 degrees C or higher, and has an HD60 or higher and HD72 or lower according to the JIS standard at -5 degrees C. The claim (having hardness)
The snow tire described in 1). (4) The snow tire according to claim (1), wherein each block has two or more of the holes.