Patent ID: 6216757
Filing Date: 2001-04-17
Classification: B60C

Abstract:
A low noise level truck and bus tire including; a carcass composed of at least one ply toroidally extending between a pair of bead cores, and a tread arranged radially outwardly of said carcass and composed on an outer cap rubber layer and an inner base rubber layer, wherein the cap rubber layer is made of a rubber having a dynamic storage modulus (E'c) of not less than 1.0.times.10.sup.8 dyn/cm.sup.2 and not more than 2.0.times.10.sup.8 dyn/cm.sup.2 and a loss tangent of not less than 0.15 and not more than 0.35, and the base rubber layer is made of a rubber having a dynamic storage modulus (E'b) of not less than 1.2.times.10.sup.8 dyn/cm.sup.2 and not more than 2.2.times.10.sup.8 dyn/cm.sup.2 and a rate of foaming of not less than 5% and not more than 50%, wherein said dynamic storage modulus (E'b) is greater than said dynamic storage modulus (E'c) and the values of dynamic storage modulus and loss tangent are determined by use of a viscoelastic spectrometer operated at an atmospheric temperature of 25.degree. C., a frequency of 52 Hz, an initial strain of 5% and dynamic strain of 1.0%.