... All weather
Road, 4WD not needed.
Rating 1.5 ... Graded Road, 4WD may be needed in poor weather.
Rating 2 ...Unimproved or Rarely Graded Road, 4WD or extra clearance
needed at times, no special driving skills required.
Rating 2.5 ...Road Rarely Maintained, 4WD, good clearance, low gears
often needed, with some extra care and a bit of driving experience useful.
Rating 3 ...Road in Difficult Terrain, Rarely maintained, 4WD, good
clearance, and low gears essential, with some driving skill and daring
required.
Rating 3.5 ... Road in difficult terrain, probably maintained only be
occasional users. Excellent stock truck or utility vehicle required, with
considerable driving skill and daring needed.
Rating 4 ... Trail either never bladed or badly eroded. Stock vehicles
in jeopardy. Modifications for improved off-road performance and top
driving skills needed.
Rating 4 + ...It is common to have as many as 10% of the vehicles
experience major mechanical failures (gears, axles, driveshafts) on these
trails.