Class A • Loads of 1-60 psi. • Recommended for pedestrians, bicycles and wheel chair traffic.   Class C • Loads of 176-325 psi. • Recommended for heavy-duty pneumatic tire forklifts and tractor trailers at speeds less than 20 m.p.h., H-20 rated.           Class B • Loads of 61-175 psi. • Recommended for medium-duty pneumatic tire traffic, autos and light trucks at speeds less than 20 m.p.h.   Class D • Loads of 326-575 psi. • Recommended for heavy-duty hard tire forklifts at speeds less than 20 m.p.h., H-20 rated.