Heavy duty pneumatic tires

A heavy duty pneumatic tire comprising a carcass of a bias structure composed of a least 12 rubberized laminated ply layers each containing organic fiber cords embedded therein, and divided into three groups, an inner group, a middle group and an outer ply group by three bead cores, the cords in said inner, middle and outer ply groups having the same diameter, said cords crossed with each other as a reinforcement for a toroidal casing inclusive of a tread, wherein in a region extending from an upper area of a bead portion of said casing within a range of 0.15 to 0.45 times a tire height as measured from a bead base of the tire, at least an average cord distance between adjacent ply layers at said middle and outer ply groups is made substantially wider than at said inner ply group and, a cord distance between adjacent ply layers at said outer ply group is substantially equal to that at said middle ply group and is within a range of 0.6 to 3.5 times a diameter of said cord used in the outer portion of the toroidal casing.