Abstract: A pneumatic radial tire includes a bead portion having a plurality of bead cores, and one or plural radial carcass plies wound up from a tire inner side toward an outer side at the respective bead cores. One-half or more of the number of end portion(s) of the radial carcass ply (plies) wound up on the bead cores is/are positioned at each bead core within a range of 35 to 55% of a tire section height as measured from the reference line of the tire section height. In accordance with this structure, rigidity from the bead portion to a side portion of the tire markedly improves. Accordingly, even when the tire is large and a load applied thereto is increased, deformation of the bead portion in the loaded state is suppressed, a strain level of the bead portion is reduced, and excellent durability of the bead portion is ensured.

Abstract: A pneumatic radial tire includes a bead portion having a plurality of bead cores, and one or plural radial carcass plies wound up from a tire inner side toward an outer side at the respective bead cores. One-half or more of the number of end portion(s) of the radial carcass ply (plies) wound up on the bead cores is/are positioned at each bead core within a range of 35 to 55% of a tire section height as measured from the reference line of the tire section height. In accordance with this structure, rigidity from the bead portion to a side portion of the tire markedly improves. Accordingly, even when the tire is large and a load applied thereto is increased, deformation of the bead portion in the loaded state is suppressed, a strain level of the bead portion is reduced, and excellent durability of the bead portion is ensured.

Abstract: An off-the-road heavy duty pneumatic radial tire is suitable to be used on irregular grounds or roads. The tire includes a carcass of radially arranged cords and a belt of a plurality of rubber coated steel cords. The belt comprises a main layer of first, second and third layers whose cords in adjacent layers are arranged inclined reversely to each other with respect to an equatorial plane of the tire and a protective layer laminated on the main layers. Cords of the protective layer are high elongation cords whose tensile breaking elongation is 1.4 to 3.0 times that of the cords of the main layer of the belt. The second layer is narrower than the adjacent first layer and much narrower than the adjacent third layer. The protective layer extends wider than the widest third layer. Edges of the protective layer are on extensions of a center line of a total thickness of the main layers.