S.C. Code Regs. 38-393.75. Tires

(a) No motor vehicle shall be operated on any tire that (1) has body ply or belt material exposed through the tread or sidewall, (2) has any tread or sidewall separation, (3) is flat or has an audible leak, or (4) has a cut to the extent that the ply or belt material is exposed. (b) Any tire on the front wheels of a truck, or truck tractor shall have a tread groove pattern depth of at least 4/32 of an inch when measured at any point on a major tread groove. The measurements shall not be made where tie bars, humps, or fillets are located. (c) Except as provided in paragraph (b), tires shall have a tread groove pattern depth of at least 2/32 of an inch when measured in a major tread groove. The measurement shall not be made where tie bars, humps or fillets are located. (d) [Reserved] (e) No truck or truck tractor shall be operated with re-grooved tires on the front wheels which have a load carrying capacity equal to or greater than that of 8.25 20 8 ply rating tires. (f) Tire loading restrictions. No motor vehicle (except manufactured homes, which are governed by paragraph (g) shall be operated with tires that carry a weight greater than that marked on the sidewall of the tire or, in the absence of such a marking, a weight greater than that specified for the tires in any of the publications of any of the organizations listed in Federal Motor Vehicle Safety Standard No. 119 (49 CFR 571.119, S5.1(b) unless: (1) The vehicle is being operated under the terms of a special permit issued by the State: and (2) The vehicle is being operated at a reduced speed to compensate for the tire loading in excess of the manufacture's rated capacity for the tire. In no case shall the speed exceed 80 km/hr (50 mph).