A heavy duty tire comprises a single carcass ply and a tread reinforcing belt. Each carcass ply turnup portion comprises a base part under a bead core and a radially outer part extending axially inwardly towards the carcass ply main portion. The belt consists of three plies of cords, wherein the cords of the radially outer ply are inclined toward one direction at an angle of from 13 to 23 degrees with respect the fire equator; the cords of the intermediate ply are inclined at an angle of from 13 to 23 degrees toward one direction being opposite to that of the radially outer ply; and the cords of the radially inner ply are arranged at an angle of from 30 to 70 degrees toward one direction being opposite to that of the radially outer belt ply.