Patent ID: 6814118
Filing Date: 2004-11-09
Classification: B60C,Y10T

Abstract:
A pneumatic tire comprisinga tread portion, a pair of sidewall portions, a pair of bead portions, a carcass comprising a ply of cords defining the innermost reinforcing cord layer extending between the bead portions, an airtight layer disposed inside said cords of the carcass ply along the inner surface of the tire, covering the substantially entire inner surface of the tire, the airtight layer is made of a first air-impermeable rubber compound and a second air-impermeable rubber compound, the first air-impermeable rubber compound forms an outer layer coming into contact with the cords, and the first air-impermeable rubber compound comprises 10 to 50 weight % of halogenated butyl rubber and/or halogenated isobutylene-paramethyl styrene copolymer and 90 to 50 weight % of diene rubber in its rubber base, the second air-impermeable rubber compound forms an inner layer defining the tire inner surface, and the second air-impermeable rubber compound comprises 60 to 100 weight % of halogenated butyl rubber and/or halogenated isobutylene-paramethyl styrene copolymer and 40 to 0 weight % of diene rubber in its rubber base, a minimum torque of the first air-impermeable rubber compound is at least 1.1 times a minimum torque of the second air-impermeable rubber compound, wherein the minimum torque is measured under a temperature of 170 deg.C., an angularly amplitude of plus/minus 1 degrees, and an oscillation of 100 cycles/minute, and the thickness of the airtight layer measured from the inner surface of the tire to the cords of the carcass ply being in a range of from 0.2 to 0.7 mm.