Abstract: An annular metal mold portion forming a tire tread is constructed by assembling a plurality of sector metal molds 2 severed in the circumferential direction, and all or some of the sector metal molds 2 are constructed of a plurality of smaller parts 3 severed in the axial direction as well as in the circumferential direction. Joining surfaces between the sector metal molds themselves each consisting of a plurality of smaller parts are formed of contour surfaces in arbitrary shape of the smaller parts. These contour surfaces are such curved surfaces that at every location a radius of curvature is 5 mm or larger and an inclination angle of a tangential plane with respect to a tire axis is 80 degrees or less.

Abstract: A split vulcanizing die comprising lower and upper molding rings with the upper ring movable relative to the lower molding ring. A side molding ring composed of a plurality of arc-shaped segments is movable in the radial direction of the die, so that when all the segments are moved to their radially innermost positions, the side molding ring is placed in tight contact with the outside circumferential surfaces of the upper and lower molding rings moved toward each other. An outer ring having an inside circumferential truncated-cone-shaped surface is provided outside the side molding ring so that said outer ring can be moved in the axial direction of said die. Oblique dovetail couplings conjoin the segments to the outer ring. The oblique planar surfaces are provided on the circumferential outside of the segments.