S.C. Code Regs. 38-393.78. Windshield wipers

(a) Every truck, and truck tractor, having a windshield, shall be equipped with at least two automatically operating windshield wiper blades, one on each side of the centerline of the windshield, for cleaning rain, snow, or other moisture from the windshield and which shall be in such condition as to provide clear vision for the driver, unless one such blade be so arranged as to clean an area of the windshield extending to within 1 inch of the limit of vision through the windshield at each side: Provided, however, That in driveaway towaway operations shall apply only to the driven vehicle: And provided further, That one windshield wiper blade will suffice when such driven vehicle in driveaway towaway operation constitutes part or all of the property being transported and has no provision for two such blades. (b) Every truck, and truck tractor, the date of manufacture of which is subsequent to June 30, 1953, which depends upon vacuum to operate the windshield wipers, shall be so constructed that the operation of the wipers will not be materially impaired by change in the intake manifold pressure.