Ro-ro is an acronym for Roll-on/roll-off. Roll-on/roll-off ships are vessels that are used to carry wheeled cargo. such as tractors, buses and trucks, or oversized cargo loaded on special flatbed, mafi or lowboy trailers. New or used automobiles that are transported by ship are often moved on a large type of RORO called a Pure Car Carrier (PCC) or Pure Car Truck Carrier (PCTC)