Patent ID: 7549453

Claim:
A method for forming a green tread rubber, the green tread rubber composed of a cap rubber layer of which outer surface forms a tread surface and a base rubber layer that adjoins the radially inside of the cap rubber layer, wherein the base rubber layer is made of a base rubber, and the cap rubber layer is made of a cap rubber, the method comprising the steps of: forming an annular base rubber layer by winding a strap-like base rubber one turn around a molding drum and jointing the circumferential end portions thereof with each other, wherein the strap-like base rubber is extruded from a rubber extruder and is cut into a certain length; and forming the cap rubber layer by successively winding and overlapping a long strip of the cap rubber in the circumferential direction and in a spiral manner on the annular base rubber layer, wherein the long strip is extruded from a rubber extruder and has a smaller width than that of the strap-like base layer, wherein a thickness T2 of the base rubber layer is 0.05 to 0.7 times a thickness T 0 of the green tread rubber measured at the tire equator, the rubber component of the cap rubber comprises not less than 80 parts by mass of a styrene/butadiene rubber per 100 parts by mass of the rubber base material, and the complex elastic modulus E 1 * thereof after vulcanization is 5.0 to 8.0 MPa, and the rubber component of the base rubber comprises not less than 50 parts by mass of a natural rubber per 100 parts by mass of the rubber base material, and the complex elastic modulus E 2 * thereof after vulcanization is smaller than said complex elastic modulus E 1 * and the difference |E 1 *-E 2 *| therebetween is not less than 2.0 MPa.