Process and drum for constructing a green tire

Expandable drum for constructing a green carcass of a tire has a periphery and includes a plurality of metal segments positioned to form a substantially cylindrical arrangement, adapted for radial expansion and compression. A thick-walled casing, positioned over the plurality of metal segments, forms the drum periphery. The thick-walled casing includes rubber and a plurality of voids arranged to have an outer periphery in the thick-walled casing. An evacuating pump is coupled to the plurality of voids. The plurality of voids form suctioning voids to suction the green carcass onto the drum periphery during compression of the drum periphery, and are coupled at radially outermost extents to a network of grooves arranged to provide wave-free and smooth contraction of green carcass during its compression, thereby avoiding bulges and creases in contracting green carcass. Radially innermost extents of the voids are coupled to evacuating pump to create vacuum in the grooves.