Abstract: A drum for producing blanks for car tires of rubber with straps wherein the drum consists of coaxial rings movable axially relatively to each other and having supporting surfaces for the beads of tire blanks. According to the invention each ring has an annular groove containing a ring insert of an elastomeric material with a high E-modul. The insert is radially stretchable and consists of a cylindrical supporting part and a disk part firmly connected therewith. The disk part in cross-section has a toggle-like bend and is supported upon the base of the groove. The supporting part is fixed to a limiting flange.