Patent ID: 6701986
Filing Date: 2004-03-09
Classification: B60C,Y10T

Abstract:
A pneumatic tire comprisinga tread portion, a pair of sidewall portions, a pair of bead portions, a carcass extending between the bead portions, and a tread reinforcement disposed radially outside the carcass in the tread portion and comprising a radially inner reinforcing cord layer disposed on the carcass crown, a reinforcing rubber layer disposed thereon, and a radially outer reinforcing cord layer disposed radially outside of the reinforcing rubber layer, the radially outer reinforcing cord layer composed of a first belt ply of cords laid at an angle of from 10 to 30 degrees with respect to the tire equator, and a band ply made of cords disposed radially outside of the first belt ply at a cord angle of not more than 5 degrees with respect to the tire equator, the radially inner reinforcing cord layer composed of a second belt ply of cords laid at an angle of from 10 to 30 degrees with respect to the tire equator in an opposite direction to that of the cords in the first belt ply, each said sidewall portion is provided on the axially inside of the carcass with a sidewall reinforcing rubber layer, which tapers towards its radially inner end and outer end from a central portion to have a crescent shape in a meridian section of the tire, the reinforcing rubber layer extending across the substantially overall tread width and made of a rubber material having a JIS-A hardness of not less than 70 degrees and a loss tangent of not more than 0.15 measured at a temperature of 70 degrees C., a frequency of 10 Hz, and a dynamic distortion of plus/minus 2%, in a tire meridian section, the thickness of the reinforcing rubber layer being in a range of not less than 2 mm at the tire equator and gradually decreasing towards the axial edges of the reinforcing rubber layer; and wherein in a meridian section of the tire under a normally inflated unloaded condition, the tire has a profile of the tread portion or continuing through the tread portion to a maximum tire section width point in each of the sidewall portions where the radius of the curvature gradually decreases towards the axially outside of the tire from the tire equator.