Pneumatic radial tire for passenger vehicle.

摘要

The invention relates to a pneumatic radial tire for a passenger vehicle, wherein at least a portion of a carcass line extending radially outwardly from the maximum width position in a carcass line of a tire fitted to a normal rim and inflated up to its normal internal pressure is configured so as to substantially conform to an equilibrium carcass line expressed by the following equations (1) and (2) calculated by using an internal pressure allotment ratio g(y) of a carcass layer (4) at the tread portion (1) that is obtained by setting the distributional configuration index alpha of the following equation (3) at 4 or more, and that a tread pattern having a directional property is provided to the tread surface thereof, wherein: in yD in yB wherein, provided that a line drawn vertically downwardly from the center of the tread portion (1) to the axle of the tire is y axis of coordinates with the axle of the tire being z axis of coordinates, yA, yD, yC, yB and eta denote as follows: yA: y axis of coordinates for the carcass line at the center of the tread portion (1); yD: y axis of coordinates for the carcass line at the effective width end portion of the belt layer (7); yC: y axis of coordinates for the carcass line at the maximum width position in a tire carcass line; yB: y axis of coordinates for the carcass line at the bead portion (3);and eta : the internal pressure allotment ratio of the carcass layer (4) at the center of the tread portion (1).