In the case of a winter tire such as studless tire, in order to enhance running performance (hereinafter “on-the-ice performance”) on an icy road surface, it is necessary to increase a road surface digging friction or an adhering friction. For this purpose, various researches have been attempted for increasing coefficient of friction of a tread rubber with respect to an icy road surface.
As one of results of researches, it is proposed to blend short fibers into the tread rubber and to orient the short fibers to a radial direction (thickness direction of the tread rubber) of the tire. This proposal has a merit that the road surface digging ability is enhanced by orienting the short fibers in the radial direction, softness of the tire in the thickness direction can be secured due to fine bumps and dips on the road surface and thus, adhering frictional force is also enhanced, and on-the-ice performance can largely be enhanced.
In recent years, as the performance and output of vehicles are enhanced, it is strongly desired to control side slip at the time of turning of the vehicle to enhance on-the-ice performance, and to prevent accidents caused by slipping.
Thereupon, it is a first object of the present invention to provide a pneumatic tire in which short fibers blended with a tread rubber are inclined outward of a vehicle and radially outward of a tire, an inclination angle α1 of the short fibers in a grounding end on an outer side of the vehicle is made greater than an inclination angle α2 of the short fibers of a tire equator and based on this structure, the side slip at the time of turning of the vehicle can largely be controlled, and steering stability on a slippery road surface is enhanced.
It is a second object of the invention to provide a producing method capable of easily forming the pneumatic tire based on an idea of using a long band-like rubber strip in which short fibers are oriented in a direction of the tire width.
USPTO Backgrounds
USPTO Backgrounds