S.C. Code § 56-5-4040
Incorporated cities and municipalities may by ordinance permit the operation within their respective jurisdictions of any motor bus or trolley coach with a maximum outside width of not to exceed one hundred and two inches. But in the case of state highways within incorporated cities no such permit shall become effective until approved by the Department of Transportation. All such permits shall specify the streets or sections of streets over which such trolley coaches may be operated. The term "trolley coach" means a vehicle which is propelled by electric power obtained from overhead trolley wires though not operated upon rails.
The Department of Transportation with respect to the state highways and local authorities with respect to other highways, may issue permits for the operation of motor buses and trolley coaches, having a lateral outside width of not exceeding one hundred and two inches upon any highway, route or routes of sufficient width in suburban areas adjacent to municipalities.
S.C. Code § 56-5-4040