Abstract: A heavy duty pneumatic radial tire comprising a carcass, a tread and a belt layer consisting of four belt plies piled radially one above another and containing steel cords therein. The four belt plies consist of a large belt ply having a width wider than that of the other belt plies, a middle belt ply arranged radially inward of the large belt ply and having steel cords oblique in the same directions as those of steel cords of the large belt ply, a first small belt ply arranged between the large belt ply and the middle belt ply and having steel cords oblique in opposite directions to those of the cords of the large belt ply and a width smaller than that of the middle ply, a second small belt ply arranged radially inward of the middle belt ply and having steel cords oblique in opposite directions to those of the cords of the large belt ply and a width smaller than that of the middle belt ply.

Abstract: An off-the-road pneumatic steel radial tire comprises a radial carcass comprised of at least one carcass ply containing steel cords and a belt superimposed about a crown portion of the carcass and comprised of at least three laminated steel cord layers. In this tire, the belt includes at least two main belt layers each containing substantially inextensible steel cords, in which steel cords included in at least one of these main belt layers satisfy conditions that a cord diameter is. the same in this layer but different from that of the remaining main belt layer, and a ratio of cord diameter in these main belt layers is within a range of 1.2-3.0, and a ratio of total breaking load of cords in these main belt layers per unit width is within a range of 1.1-2.0 times.

Abstract: A heavy duty pneumatic bias tire having a thick case gauge is disclosed, which comprises a carcass of a bias structure composed of a plurality of carcass plies each containing organic fiber cords and a plurality of bead rings spaced from each other in each of bead portions of the tire, both end portions of a plurality of the carcass plies being turned-back around each of the bead rings from the inside to the outside of the tire. In the tire of this type, the ends of the carcass plies turned-back around the bead rings except the axial innermost bead ring are positioned in the outside of the region "C" between the planes "A" and "B" in each of sidewall portions of the tire.