S.C. Code § 56-5-4210
Anything in this article to the contrary notwithstanding, the Department of Transportation with respect to state highways and local authorities with respect to highways under their jurisdiction may prescribe, by notice as herein provided, loads and weights and speed limits lower than the limits prescribed in this chapter and other laws, whenever in their judgment any road or part thereof or any bridge or culvert shall by reason of its design, deterioration, rain or other climatic or natural causes be liable to be damaged or destroyed by motor vehicles, trailers or semitrailers, if the gross weight or speed limit thereof shall exceed the limits prescribed in such notice. And the Department of Transportation or such local authority may, by like notice, regulate or prohibit, in whole or in part, the operation of any specified class or size of motor vehicle, trailer or semitrailer on any highways or specified parts thereof under its jurisdiction, whenever in its judgment, such regulation or prohibition is necessary to provide for the public safety and convenience on such highways or parts thereof by reason of traffic density, intensive use thereof by the traveling public or other reasons of public safety and convenience. The notice or the substance thereof shall be posted at conspicuous places at terminals of and all intermediate cross-roads and road junctions with the section of highway to which such notice shall apply. After any such notice shall have been posted, the operation of any motor vehicle or combination contrary to its provisions shall constitute a violation of this chapter.
S.C. Code § 56-5-4210