1 2WD road.
2 Graded road. 4WD may be needed in poor weather.
3 Unimproved road. 4WD or extra clearance needed occasionally, with no special driving skills required.
4 Road rarely maintained. 4WD, good clearance, low gears often needed, with some extra care and a bit of driving experience useful.
5 Road rarely maintained, in difficult terrain. 4WD, good clearance, and low gears essential, with some driving skill and daring required.
6 Road probably maintained only by occasional users, in difficult terrain. Excellent stock truck or utility vehicle required, with considerable driving skill and daring needed.
7 Trail never maintained. Stock vehicles are in jeopardy. Modifications for improved off-road performance and top driving skills needed.
8 Only for dirvers that are not concerned about any body damage to their vehicles. There is a great possability that your vehicle will come back without somthing (axles, driveshafts, gears, etc.) that it needs in order to operate properely. And you may come back needing to change somthing too : ).