Pneumatic radial tire with under-belt pad and specified intermediate rubber layer rubber compound

摘要

A pneumatic radial tire is provided which comprises an under-belt pad (3) provided circumferentially between edge portions of a belt (1) and a carcass in a shoulder portion thereof, the under-belt pad (3) being of a rubber compound containing 10 to 60 parts by weight of carbon black and 3 to 30 parts by weight of silica with a total amount of carbon black and silica being 20 to 65 parts by weight, 2 to 5 parts by weight of sulfur and 0.5 to 3 parts by weight of resorcin or a resorcin derivative all relative to 100 parts by weight of rubber, and 0.5 to 2 parts by weight of hexamethylene tetramine or a melamine derivative as a methylene donor relative to 1 part by weight of the resorcin or the resorcin derivative, and having a dynamic viscoelasticity E' or 5 MPa to 10 MPa, a loss tangent tandelta of 0.10 to 0.18 and a 300% modulus of 11 MPa to 15 MPa.