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1. A pneumatic radial tire for heavy loads comprising a tread portion, a pair of sidewall portions, a pair of bead portions each having a bead core therein, a radial carcass composed of at least one carcass ply including a body portion extending toroidally between the bead cores of the bead portions and turn-up portions turned up along the bead cores, and a tread rubber disposed on an outer circumferential side of a crown region of the carcass, wherein:
in a widthwise cross section of the tire when the tire is mounted to an application rim and inflated with a specified internal pressure, turnoff point is defined at an end of an inclined area inclined both outward in a tire width direction and inward in a tire radial direction from a tread ground-contact end of the tread rubber; a maximum tire width position is positioned further outward in the tire width direction than a tire outer surface corresponding to a maximum carcass width position and the turnoff point, and is also positioned further outward in the tire radial direction than the maximum carcass width position, further inward in the tire radial direction than the turnoff point; an angle α is defined as an acute angle that a line joining an intersection between a virtual line and the tire outer surface and the maximum tire width position forms with respect to a radial line segment, the virtual line passing through the maximum carcass width position in a direction parallel to a tire axis line, and the angle α satisfying a relationship 0<α≦30°; a distance h is defined as a distance in the tire radial direction from a tread center to the maximum tire width position, the distance h ranging from 0.20SH to 0.40SH where SH is a tire section height, and an angle β is defined as an acute angle that a line joining the maximum tire width position and the turnoff point forms with respect to the radial line segment, the angle β satisfying a relationship 0<β<30°; and a reinforcing rubber is disposed such that at least a portion of the reinforcing rubber is positioned axially between the body portion and the turn-up portion of the carcass, and said reinforcing rubber has an upper end located at a height equal to 0.15SH to 0.25SH, as measured outward from the virtual line that intersects with the maximum carcass width portion, and a lower end at a height equal to 0.20SH to 0.30SH, as measured inward from said virtual line, the reinforcing rubber having a modulus of elasticity M at 300% elongation ranging from 60 to 100 kgf/cm2 and a rebound resilience coefficient R in a range 0.4<R<0.7. |
