The invention relates to a tire for heavy vehicle of the agricultural or construction type, comprising a carcass reinforcement radially surmounted by a crown reinforcement, itself topped radially by a tread, said tread being joined to two beads by means of two sidewalls. According to the invention, the tire is such that the form ratio H/S is less than 0.75 and the ratio of the width of the tread A to the height of deflection B of the crown is greater than 17.