The International Harvester R-Series was a family of trucks that debuted for the 1953 model year. The R-Series succeeded the International Harvester L-Series, and was available in a wide range of paylod capacities. Light, medium, and heavy duty variants were built, with their differences denoted by the letter 'R' followed by three numbers (R110-R130 were light duty, R140-R180 were medium duty, and R190-R220 were heavy duty). This family of trucks was powered by a range of inline six engines available in gasoline and diesel versions. Light and medium duty variants of the R-Series ended production in 1955, with these trucks replaced by the International Harvester S-Series. Heavy duty versions of the R-Series remained in production until 1972.