PURPOSE: To increase high-speed stability and turning stability while maintaining riding comfortableness by forming a rubber layer arranged inside a tread part ion the radial direction of a carcass with a rubber compound containing specified amounts of carbon black and short fibers.

CONSTITUTION: A tire is formed so that a tread width WT is the maximum tire width, a tread surface 2A is bent protrudedly in tire axis direction, and a rubber layer 9 is arranged inside a tread part 2 in the radial outward direction of a carcass 6. Also the carcass 6 is formed of a carcass plies 6A and 6B in which bias-arranged carcass cords are arranged, the rubber layer 9 is formed of a rubber compound which contains a carbon black of 30 to 60 pts.wt. with an iodine adsorption amount of 35 to 120mgr/gr, and short fibers of 20 to 50 pts.wt. arranged at an angle of 0 to 20° relative to a tire equator C for a rubber component of 100 pts.wt. Thus cornering force can be reduced to enhance the high-speed stability and turning stability.