A pneumatic radial tire which includes a tread portion defining an overall diameter of the tire under a normally-inflated unloaded state and a ground contacting width under a normally inflated loaded state; a pair of sidewall portions defining an overall width of the tire there between under the normally-inflated unloaded state; a pair of bead portions each with a bead core therein; a carcass extending between the bead portions through the tread portion and, sidewall portions; and a belt disposed radially outside the carcass in the tread portion, wherein the overall diameter of the tire is in the range of from 750 to 820 mm; the ground contacting width is in the range of from 85 to 90% of said overall width of the tire; and the carcass comprises an ultrahigh-turnup ply extending between the bead portions through the tread portion and sidewall portions and turned up around the bead core in each of the bead portions so that the turned-up portions each extend radially outwardly into the tread portion through the sidewall portions, and the turned-up portions each terminate axially inward of the axial ends of the belt.