Abstract: A die assembly for generating a green tread extrudate for pneumatic tire fabrication is presented. Fundamentally, the invention includes a preform die of fixed configuration, having passages and openings therein for passing both a base stock material and a cap stock material. The openings are separated by a partition. Upper and lower final die plates are then formed to communicate with the openings, one for the cap stock, and the other for the base stock. The configuration of the die portion of the die plates control not only the external geometry of the resulting extrudate, but also the geometry of the junction between the cap stock and the base stock in the extrudate. The invention accommodates a broad range of tire specifications with the simple change of die plates.