PNEUMATIC RADIAL TIRE

PURPOSE:To improve comfortableness while maintaining operation stability by forming a carcass line shape of combination of the predetermined circular arcs and reducing a radius of curvature of the circular arc shape having a curvature center on the tire inside in a crown part end part area. CONSTITUTION:A shape of a carcass line is formed of a circular arc, which has the center of curvature on a tire equatorial surface CL in the tire inside direction and is provided with a radius of curvature R1, in the tire width directional central part area in a tread 22. Further, in the position substantially corresponding to a tire width directional inside end 24A of a belt reinforcing layer 24, a carcass line is formed of a circular arc, which has the curvature center in the tire outside direction and is provided with a radius R2 of curvature, and a circular arc, which has the curvature center in an opposed part to a buttress part 26, in other words, in the tire inside direction in a crown part width directional end part of a carcass 12 and is provided with a radius R3 of curvature. Therefore both of riding comfort maneuvering stability can be accomplished at the same time, as the radius R3 of curvature R3 is small.