Everything seems to have its standard of measurement. Earthquakes have their Richter Scale, sound has its decibels, and heat has its British Thermal Units. It does not seem unreasonable then, that we should be able to quantify the degree of difficulty that a road or jeep trail should present. The scale, which we modestly call the Mitchell Scale, was stolen from mountain climbers who have their own type of madness. It begins with Class I, the easiest trail conceivable, to Class VI, the impossible.
This includes just about type of semi-improved road, which receives little or no maintenance, over which you can drive a standard passenger car with little fear of damaging the undercarriage.
This road might have a high center, or an occasional rock sticking up, either of which could cause problems for ordinary passenger cars. While this class of road may possibly be negotiated by a skilled driver operating a low-slung automobile, we nevertheless recommend this road for two-wheel drive vehicles having higher ground clearance than most passenger cars. Four-wheel drive and dual range gears are not needed.
The surface of this road may be very rocky, very sandy, or very steep. This is the easiest type of road that would prudently require the driver to use four-wheel drive. A transfer case offering low range gears and locking axles is not needed. Unless they are excessively wide, most off-the-shelf SUVs and pickups, even those being driven by drivers having limited off- road experience, should be able to handle this road without any vehicle damage.
Here we begin to separate the men from the boys, both in terms of driver experience and the type of vehicle. We only recommend this severity of road for fully experienced drivers, who know the capabilities of their vehicle very well. A transfer case with ultra low-range gears is necessary, as is at least one full-locking axle, skid plates protecting everything vital underneath, and oversize tires of at least 33 inches that can be easily deflated and inflated on the trail. Be aware that some minor vehicle body damage could occur, unless the driver has an outside spotter to act as a guide. Roads and trails having significant portions of Class IV are unsuitable for more than half of the unmodified pickups and SUVs on the market today.
This is an extremely difficult road, totally unsuitable for 98% of new vehicles as they leave the factory. The following items are a must: A transfer case with low range gears, two to four-inch lift of the suspension, locking axels both front and rear, skid plates protecting the entire undercarriage, roll bars, and a winch. Even with a spotter, some vehicle damage will occur. This is not a trail for the faint of heart, a novice four-wheeler, or a stock right out of the factory vehicle.
This is extreme four-wheeling for hard-core rock crawlers only. Besides the equipment and modifications listed above, a full rigid cage is recommended. Even with an experienced driver in a highly modified vehicle, the chances of a rollover are quite high!