Methods and apparatuses for coding occlusion layers, such as occlusion video data and occlusion depth data in 3D video, are disclosed. The head portion is generally tear-drop in shape and has a width no greater than 12 inches. A first via is provided that connects the slit in the nipple to a flow channel leading into a fluid reservoir. A block element on the center tread region side of the groove has multiple circumferentially spaced apart and laterally extending sipes extending across the block element. The bumper has at a fastening point a depression to receive a head of the screw and a recess for the mounting of the screw cover.