The term 'trucking rig' refers to a large vehicle that is used for transporting goods. It is typically composed of a tractor unit and one or more trailers. The most common type of trucking rig is the SEMI, which is a combination of a tractor unit and a single trailer. The tractor unit is usually powered by a diesel engine and the trailer is connected to the tractor unit via a fifth wheel coupling. The SEMI is capable of carrying large loads and is often used in long-distance hauling.