Patent ID: 8387670

Claim:
A tire noise reduction device comprising at least one sound absorbing member of flexible polyurethane foam to be attached to an inner surface of a tire facing a cavity of the tire, wherein: the at least one sound absorbing member comprises a first sound absorbing layer placed on a tire inner surface side thereof and a second sound absorbing layer placed on a tire reverse inner surface side thereof, the second sound absorbing layer being disposed on the first sound absorbing layer; the first sound absorbing layer has a tear strength (N/cm) per unit density (kg/m 3 ) which is equal to or more than 0.30; the second sound absorbing layer has a density which is lower than that of the first sound absorbing layer; the first sound absorbing layer has a density of 18 kg/m 3 to 40 kg/m 3 , and wherein the density of the second absorbing layer is 40% to 80% of that of the first sound absorbing layer; the second sound absorbing layer is of a thickness that is greater than or equal to that of the first sound absorbing layer, one of either the first sound absorbing layer or the second sound absorbing layer is formed of one sound absorbing member extending annularly in the tire circumferential direction and the other of the first or second sound absorbing layers is formed of a plurality of the sound absorbing members annularly disposed at prescribed intervals in the tire circumferential direction, with each of said plurality of sound absorbing members being separated from each other by a gap that extends the full width of the relevant sound absorbing layer, and said second sound absorbing layer extends annularly in the tire circumferential direction.