Class descriptions for Ice Trials:

Class A (unlimited) is for modified (racing) cars

A-1 = FWD unlimited, any wheel size, studded racing tires
A-2 = RWD unlimited, any wheel size, studded racing tires
A-3 = 4WD unlimited, any wheel size, studded racing tires

Classes B through D are for unmodified street cars

B-1 = FWD, 13" wheels & smaller
B-2 = FWD, 14" wheels
B-3 = FWD, 15" wheels & larger
B-4 = FWD, stock car car with studded (racing) tires

C-1 = RWD, 13" wheels & smaller
C-2 = RWD, 14" wheels
C-3 = RWD, 15" wheels & larger
C-4 = RWD, stock car with studded (racing) tires

D-1 = 4WD, 13" wheels & smaller
D-2 = 4WD, 14" wheels
D-3 = 4WD, 15" wheels & larger
D-4 = 4WD, stock car with studded (racing) tires