PURPOSE: To contrive an improvement in sticking accuracy of a tread of a flat tire, by a method wherein the tread is molded by dividing the same into three of a center tread and a right and left treads and the treads each are stuck in order onto a tire carcass and stitched.

CONSTITUTION: A tread 5 divided into three is extrusion-molded beforehand into a center tread 5a, which is in almost a trapezoidal sectional form, and two shoulder treads 5b and in almost a uniform width. The treads 5b, 5b are stuck beforehand to side walls 6a, 6b and a casing is stuck onto a tire carcass 1 under a flat state. Then after a tread 5a is stuck through lamination onto a molded breaker 2 of the tire carrass by inflating a tire, stitching is performed respectively toward a shoulder part Wb from the central part of the tread 5a by a stitching roll 4. Then the treads 5b, 5b are stuck by turning up the tips of them and the stitching is performed respectively toward a tread 5a side from a tire bead 7 side by the sticking roll 4.