Patent ID: 7810535

Claim:
A pneumatic radial tire having an aspect ratio of 55% or less and a tire outer diameter of 720 mm or more, in which a carcass layer is disposed in the inner side of the tire to extend from a tread portion to left and right bead portions through sidewall portions, respectively, and a plurality of plies of belt layer are disposed on the outer circumferential side of the carcass layer, wherein the carcass layer is formed of a single ply, both ends of the carcass layer are folded back from the inner side of the tire to the outer side thereof around left and right bead cores, respectively, so as to wrap corresponding bead fillers, each end of the folded-back portions of the carcass layer is wrapped on the inner side of each end of the belt layer by not larger than 10% of a maximum width of the belt layer, and the hardness of the bead fillers is 65 to 80 in terms of JIS durometer A hardness, and the height hb thereof from a bead base is 10 to 20% of the cross-sectional height H of the tire, wherein a reinforcement layer composed of an organic fiber cord is disposed to extend in a tire radial direction along the bead core and the bead filler between a main body portion and each folded-back portion of the carcass layer; and a height hr of the reinforcement layer in a tire radial direction is 40 to 60% of the cross-sectional height H of the tire, wherein the reinforcement layer is wound so as to wrap the bead core and the bead filler.