Run-flat pneumatic radial tire

Claim 1

In a radial tire having an aspect ratio of up to 50%, a run-flat pneumatic radial tire characterized in that: a reinforcing liner layer made of a rubber having a complex modulus at 20° C., (E* 20 ,) of at least 16 MPa, a ratio of a complex modulus at 100° C., (E* 100 ,) to said complex modulus E* 20 , (E* 100 /E* 20 ) of at least 0.80, a 100% modulus of at least 60 kg/cm 2 and a loss tangent (tan δ) at 100° C. of up to 0.35, said E* 20 , E* 100 , and loss tangent at 100° C. being measured under conditions of a frequency of 20 Hz, an initial strain of 5% and a dynamic strain of 1% elongation, and having a crescent sectional shape is disposed inside a carcass layer at sidewall portions in such a manner that one of its end portions overlaps with the end portion of a belt layer of a tread portion and the other end portion overlaps with a bead filler of said bead portion; said bead filler of said bead portion being made of a rubber having a JIS--A hardness of from 60 to 80 and has a height h of up to 35 mm from a rim base of said bead portion in a direction vertical to the axis of rotation of said tire; and said carcass layer consisting of inner and outer two layers, said inner carcass layer is turned up from inside to outside said tire around said bead core so that its end is positioned at a position higher than the height h of said bead filler and is clamped between said inner carcass layer and said outer carcass layer and an end of said outer carcass layer is disposed axially outward of said bead core without being turned up around said bead core.