a conveyor assembly is provided for movably supporting a tire of a vehicle . the conveyor assembly includes a track , a dolly , and a trapdoor assembly . the track is configured for supporting the tire of the vehicle . the track terminates at an edge , and a gap is defined beyond the edge . the dolly is configured to move along the track to the edge so as to guide the tire along the track to the edge . the trapdoor assembly is configured to substantially cover the gap when in a closed position and is movable to an open position to uncover the gap and allow the dolly to translate around the edge . the trapdoor assembly includes a device configured to prevent a human from inadvertently opening the trapdoor assembly .