Low section profile pneumatic radial tire for heavy vehicles

A low section profile radial tire for heavy vehicles the cross-sectional configuration uninflated defined in a metal mold of which has an aspect ratio of smaller than 0.85 and a crown flatness of larger than 2.0 and which comprises a carcass formed by plies, a number of cords of which lie in a substantially radial plane, a belt formed by a plurality of inextensible layers and superimposed about said carcass and extending over substantially the total width of a crown of a tread portion of the tire, and a cushion rubber inserted between said carcass and belt, said tire constructed to satisfy the following conditions:

• 1. the thickness of the tread portion which extends along the crown region is substantially uniformly distributed over 35-60% of the maximum width of the inextensible layers which comprise a tension member of said belt,
• 2. said cushion rubber formed of a rubber stock triangular in cross section having a thickness arranged outside both sides of the center region of the crown, said cushion rubber gradually increasing the thickness of the tread portion toward the hump portion of the tire, and
• 3. the thickness of said cushion rubber limited to a range of 25-50% of the thickness of that tread portion which is located at the crown center position, the thickness of said cushion rubber being defined by a distance from the the end of the inextensible layer having the maximum width to the carcass, the distance being measured on a normal line which is drawn from the end of the inextensible layer having the maximum width perpendicular to the carcass ply.