Abstract: A plant for assembling elastomeric pneumatic tires having a plurality of assembling drums (2) moveable along a predetermined assembling path. Each drum encounters, according to a pre-established sequence, a number of primary work stations (10, 11, 12, 13) each intended for the application of a respective main component (4, 5, 6, 7) common to a plurality of carcass types included in a predetermined production range. Alongside the primary stations are auxiliary work stations (14, 15) intended for applying specifically provided accessory components (8, 9), each being designed for a particular carcass type. Each auxiliary station can be removed and replaced by a different station depending on the type of process to be carried out and is movable between a rest position in which it is perpendicularly moved away from the assembling path and a work position in which it is operatively disposed along the assembling path, in order to execute the application of the respective accessory component.