Method for manufacturing a cuff on a plastic tube (14 30) comprising an inner tube (1 21) and an outer sheath (6 23) covering said inner tube (1 21). The outer sheath (6 23) comprises at least a portion to be molded for producing a cuff. The method comprises a covering step including an injection operation in which air is intermittently or continuously injected between the inner tube (1 21) and sheath (6 23).
