S.C. Code Ann. § 56-5-3630: Manner in which motorcycles must be operated.

(A) A person operating a motorcycle shall ride only upon the permanent and regular seat attached thereto and the operator shall not carry any other person nor shall any other person ride on a motorcycle unless the motorcycle is designed to carry more than one person, in which event a passenger may ride upon the permanent and regular seat if designed for two persons, or upon another seat firmly attached to the motorcycle at the rear or side of the operator.

(B) A person shall ride upon a motorcycle only while sitting astride the seat, facing forward, with one leg on each side of the motorcycle.

(C) No person shall operate a motorcycle while carrying any package, bundle or other article which prevents him from keeping both hands on the handlebars.

(D) No operator shall carry any person, nor shall any person ride, in a position that will interfere with the operation or control of the motorcycle or the view of the operator.

(E) No person shall ride upon a motorcycle as a passenger unless, when sitting astride the seat, the person can reach the footrests with both feet. Provided, the provisions of this section shall not apply to persons riding in a motorcycle sidecar.

(F) No person riding upon a motorcycle shall attach himself or the motorcycle to any other vehicle on the roadway.