A main tilting door for the closure of an access opening of a room includes two fixed uprights, including vertical sliding guides, and one fixed crosspiece associable with each other to define a fixed frame. The door includes two movable uprights and two movable crosspieces associable with each other to define a movable frame. The door includes tilting movement device/unit/component/apparatus or the like including two lateral supporting arms each having a first end which can be hinged to an intermediate area of the movable uprights and a second end which can be hinged to a top of the fixed uprights; and two sliding supports movable along the vertical sliding guides. The door includes panels associable with the movable frame. At least one of the movable uprights and the movable crosspieces includes a sliding track and cursors movable along the sliding track, the panels associable with the cursors.