Abstract: A pneumatic radial tire for heavy loads, having steel belt layers provided on the inner side of a tread, and a tread pattern having a plurality of divisional ribs separated by a plurality of main grooves extending in the circumferential direction of the tire, characterized in that at least the inner vertical surfaces of left and right outermost main grooves out of the main grooves are formed so as to extend zigzag in the circumferential direction of the tire, narrow grooves which extend continuously in the circumferential direction of the tire being provided at the shoulder side edge portions of ribs internally adjacent to the outermost main grooves, the width W.sub.4 of the narrow grooves being set to a level in the range of 0.

Abstract: A pneumatic tire having a carcass ply of metal cords arranged and embedded in the radial direction in a rubber is disclosed. This carcass ply has a natural sectional profile, and the position of the carcass ply in the shoulder portion of the tire satisfies the requirement of 0.3.ltoreq.t.sub.2 /t.sub.1 .ltoreq.1.0 in which t.sub.2 designates the thickness of the tire inside the carcass ply and t.sub.1 designates the thickness of the tire outside the carcass ply. In this shoulder portion, the thickness of an inner liner layer inside the carcass cord is gradually reduced toward the center of the tire top and the maximum width position of the tire. This pneumatic tire is preferably used for a high-load vehicle.

Abstract: A radial ply pneumatic tire, having a high durability, comprising an improved bead portion thereof which comprises a bead wire bundle, a carcass ply of a metal tire cord fabric and a reinforcing ply, all embedded in a rubber matrix, the reinforcing ply having a portion thereof located in the outside surface layer in the bead portion and comprising a woven multifilament fabric consisting of multifilament warps in a density of 20 to 65 yarns/50 mm and multifilament wefts in a density of 20 to 65 yarns/50 mm and an endmost point of the portion of the reinforcing ply in the outside surface layer of the bead portion is located farther from the bead wire bundle than the endmost point of the carcass ply.