Abstract: A low section profile pneumatic radial tire for heavy vehicles used for recently developed transport facilities such as a trolley bus, mono-rail vehicle, driverless vehicle, sub-way vehicle, etc. is disclosed. The low section profile pneumatic radial tire for heavy vehicles is constructed to satisfy the following three conditions, i.e.1. a thickness Gm of that tread portion which extends along a crown center region SW2 is substantially uniformly distributed over 35-60% of the maximum width SW1 of those inextensible layers which mainly consist of a tension member of a belt,2. a cushion rubber formed of a rubber stock which is triangular in cross-section and has a thickness Gs is arranged outside both sides of the center region of a crown and inserted between a carcass and a belt so as to gradually increase the thickness of the tread portion toward the hump portion of the tire, and3.