S.C. Code Regs. 38-393.42. Brakes required on all wheels

(a) Every commercial motor vehicle shall be equipped with brakes acting on all wheels. (b) Exception. (1) Trucks or truck tractors having three or more axles (i) Need not have brakes on the front wheels if the vehicle was manufactured before July 25, 1980; or (ii) Manufactured between July 24, 1980, and October 27, 1986, must be retrofitted to meet the requirements of 38-393 within one year from February 26, 1987, if the brake components have been removed. (2) Any motor vehicle being towed in a driveaway towaway operation must have operative brakes as may be necessary to ensure compliance with the performance requirements of Regulation 38-393.52. This paragraph is not applicable to any motor vehicle towed by means of a tow bar when any other vehicle is full mounted on such towed motor vehicle or any combination of motor vehicles utilizing three or more saddle mounts. (See Regulation 38-393.71(a)(3).) (3) Any full trailer, any semitrailer, or any pole trailer having a GVWR of 3,000 pounds or less must be equipped with brakes if the weight of the towed vehicle resting on the towing vehicle exceeds 40 percent of the GVWR of the towing vehicle.