PROFILE STRUCTURE OF RADIAL PNEUMATIC TIRE FOR PASSENGER CAR HAVING IMPROVED RUN-FLAT PERFORMANCE

摘要

A profile structure of a pneumatic radial tire in a vehicle for improving run-flat performance is provided to improve riding comfort by modifying a profile of a tread and a carcass profile of a side wall and reinforcing the side wall. A belt layer(5) and a carcass(2) are formed in a tread(1), and the carcass is arranged in a side wall and connected to a bead core(4a) of a bead part(4). The bead part is placed in a rim flange(3) in a pneumatic radial tire, and a bead point of the carcass is formed around section height of 30 to 50% to a base line of the rim flange. The bead point of the carcass is connected to an end of the belt layer by a flexible carcass profile having the radius of curvature(RC1) of 25 to 40 mm, and the middle portion of the side wall is placed at the section height of 45 to 60% from the base line of the rim flange. The lower radius of curvature(RC2) of the carcass contacted to the bead point and connected to the bead core is 40 to 90 mm, and the angle between a tangent line(L) of the carcass and a perpendicular line of the bead point is 0 to 40‹. The tread is composed of triple read radiuses formed in the rate of 300 ~ 550 mm : 500 ~ 800 mm : 100 ~ 200 mm.