A tire mold including a pair of shells (2) for molding the side walls of tire and a ring or sectors (1) for molding the tread of the tire and in which each sector (1) of the mold includes an outer support (10) and an inner mold fitting (11). The contact of the sectors with each other and of the sectors on each side wall molding shell (2) takes place via segments (3) of small cross section, compressed elastically upon the closing of the mold, so as to assure complete tightness of the mold.