JPS63265706A - Flat radial tire for small truck - Google Patents

Abstract

PURPOSE:To improve the running stability of a tire on its rutted snow road, by providing subgrooves in a radial direction of the tire in its tread surface shoulder part and forming plural notches, connecting the subgrooves, in the full region of specific width from a shoulder point to a tire center side. CONSTITUTION:A tire, providing plural subgrooves 1 in a tread surface shoulder part further plural notches 4 in a peripheral direction EE' of the tire, connects the fellow subgrooves 1, 1. It is preferable to form the width of this notch 4 to about 0.5-1.0mm and its depth to about 50%-80% the depth of a main groove 2. Further the tire forms the notches 4 in the full range to a distance B of 10% the grounded width A of the tire in the direction of a tire center line l from a shoulder point 5. By this constitution, running stability of the tire on its rutted snow road and escape quality of the tire from its rutted snow road can be improved.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a flat radial tire for small trucks that has significantly improved ability to escape from ruts on snowy roads and improved running stability on rutted snowy roads. .

[Prior art]

Conventionally, flat radial tires for small trucks, which are used for 2-ton to 3.5-ton small trucks, have a large trend radius and short tread contact width due to snowy roads, so the rear tires are particularly susceptible to damage from ruts on snowy roads. There is a problem with not being able to escape smoothly.

This is because, as shown in FIG. 2, the falling tire 11 has a large trend radius within the ruts 10 of the snowy road, and the shoulder portion 12
Only the tread is in contact with the ground (the tread contact width is short)
Also, since the flat tire has a short ground contact length, the ground contact area becomes extremely small (especially noticeable when the vehicle is empty).

Therefore, the inventors of the present invention believe that it is necessary to take measures to prevent the rear tire from sliding down in the radial direction (tire width direction) when the rear tire escapes from the rutted road, and therefore
c”F.

As a result of research to improve the FC, it was found that the FC is quite disadvantageous in terms of size (large tread radius, short tread contact width due to snowy roads), so the contact area (near the shoulder area)
We found that it was necessary to increase F[, -FF at , and came up with the present invention.

Here, Fc, Fo, and FF each mean the following.

Fc: Frictional force of rubber...17 Friction resistance force at the part where the rubber itself is in contact with the road surface.

FD: Edge effect (radial direction) -111--The force that the block edges and sipe edges of the tire pattern dig into the road surface.

F.: Frictional force on the groove wall - 1 - Working between the side of the groove of the Bakoon and the snow<)? Low paper drag.

[Purpose of the invention]

The present invention relates to the above F. - To provide a flat radial tire for small trucks, which has been achieved by increasing the FF and has significantly improved ability to escape from ruts on snowy roads and improved running stability on rutted snowy roads. With the goal.

[Structure of the Invention] For this reason, the present invention provides a plurality of sub-grooves in the tire radial direction in the shoulder portion of the tread surface, and a plurality of cuts in the tire circumferential direction, and connects the sub-grooves with the cuts. The present invention further provides a flat radial tire for small trucks, characterized in that the above-mentioned cuts are arranged in the entire area up to 10% of the tread contact width in the direction from the shoulder point to the tire center line.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of a tread pattern of a radial tire of the present invention. In FIG. 1, a plurality of sub-grooves 1 are provided in the shoulder portion of the tread surface in the tire radial direction FF'. 2 represents a main groove arranged annularly in the tire circumferential direction EE', and 3 represents a block.

(1) In the present invention, a plurality of sub-grooves 1 are provided in the shoulder portion of the tread surface as described above, and a plurality of cuts 4 are provided in the tire circumferential direction EE'.
connects the sub-grooves 1, 1 (the notches 4 are arranged such that both ends thereof reach the sub-grooves 1).

The width of the cut 4 is preferably 0.5 mm" to 1.0 mm. The depth of the cut 4 is preferably about 50% to 80% of the depth of the main groove 2.

Table 1 below shows the results of tests on snowy road running stability and snowy road rut escape performance with various numbers of cuts (feeling evaluation score using a 10-point scale). From Table 1,
It can be seen that when the number of incisions is plural, it is excellent.

Noshi F None 6.0 6.01 6
．． 0 6.5 3 trees 7.0 7.5 (2) Furthermore, in the present invention, shoulder point 5
Trend ground contact width A in the direction from tire center line 2
The cut 4 is arranged in the entire area up to 10% of the distance B, that is, the entire area up to the distance B (B/A=10%).
.

Here, the shoulder point refers to the boundary between the tread surface and the side surface.

Table 2 below shows the results of tests on snowy road running stability and snowy road rut escape performance with various B/A ratios (the number of cuts was set to 3). From Table 2, B/A is 10%
If it is within the range, it can be seen that the driving stability due to snowy roads and the ability to escape from snowy roads are good (feeling evaluation score based on a 10-point system).

(Margin below this page) Table 1 5 7.0 7
．． 08 7.0
7.510 7.0
' 7.512 6.5
7.015 6.5
6.520 6.0
6.0 [Effects of the Invention] As explained above, according to the present invention, a plurality of sub grooves are provided in the tire radial direction in the shoulder part and a plurality of circumferential cuts are arranged, so that the rigidity of the shoulder part is improved. decreases and an edge effect occurs in the tire radial direction, so the following effects can be achieved.

■ It is possible to stabilize driving on rutted roads made of snow.

■ The ability to escape from rutted roads made of snow can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the trend pattern of the radial tire of the present invention, and FIG. 2 is an explanatory diagram showing the state when the tire returns to the mountain. ■...Minor groove, 2...Main groove, 3...Block, 4...
...Notch, 5...Shoulder point, 10...
-Ruts on snowy road, 11...rear tire, 12...shoulder area.

Claims (1)

[Scope of Claims] A plurality of minor grooves are provided in the shoulder portion of the tread surface in the tire radial direction, and a plurality of notches are provided in the tire circumferential direction, and the minor grooves are connected by the notches,
Furthermore, a flat radial tire for a small truck, characterized in that the cut is arranged in the entire area from the shoulder point to 10% of the tread contact width A in the direction of the tire center line.