Patent ID: 8104523

Claim:
A pneumatic tire comprising a carcass structure having at least one carcass ply and at least one annular reinforcing structure associated with said carcass ply, a tread band made of an elastomeric material at a radially outer position with respect to said carcass structure, a belt structure interposed between said carcass structure and said tread band and a pair of axially opposite side walls on said carcass structure, the tread band comprising: i) at least one radially extending first sector substantially of a first elastomeric material; ii) a plurality of radially extending second sectors positioned at axially opposite sides of said at least one first sector and substantially of a second elastomeric material; iii) at least one longitudinal groove formed in said at least one first sector and extending substantially for the entire circumferential development of the tread band, the at least one longitudinal groove defining a cross section; wherein said first elastomeric material has a modulus of elasticity under compression at 23° C. greater than the modulus of elasticity under compression at 23° C. of said second elastomeric material, wherein the modulus of elasticity under compression at 23° C. of said first elastomeric material is 20 to 80 MPa, and wherein a ratio between an IRHD hardness at 23° C. of the first elastomeric material and an IRHD hardness at 23° C. of the second elastomeric material is 1.15 to 2.70 such that the cross section of the at least one longitudinal groove remains substantially constant when a radially outer surface of the tread band is in contact with the ground.