Hot rods are custom-built cars. Originally the term was used to the practice of taking an old car, usually a Ford, and improving its performance by reducing weight (usually by removing roof, hood, bumpers, windscreen and fenders), lower it, change or tune the engine to give more power, add fat wheels for traction and paint it to make it stand out. The term may have originated from "hot roadster" and the term was used in the 1950s and 1960s as a derogatory term for any car that did not fit into the mainstream. Other sources indicate that the term was derived from replacement of connecting rods in engines to allow higher RPMs to be reached without parts failure. When hot rodding became commercialised in the 1970s, magazines and associations catering to "street rodders" were started.