Offroad Trail Rating Systems
Why use a "difficulty" rating system
Although Offroading Home trails come from a variety of sources and use maps with fairly divergent difficulty rating systems we try to use a system similar to that used in the "Trails" series of books from Adler Publishing. It seems a bit "comprehensive" at first but allows some degree of standardization, which is good.
- Trail Difficulty Rating Systems
- Rating 1 - Graded dirt trail but suitable for a normal passenger vehicle. Normally with gentle grades, fairly wide track, and very shallow (if any) water crossings.
- Rating 2 - High clearance vehicles are preferred but NOT necessary. These are dirt roads, but not suitable for normal passenger vehicles due to rocks, grades, water crossings or ruts. Passing and mud are not a concern under normal weather and circumstances.
- Rating 3 - High clearance 4WDs are preferred but any high clearance vehicle is acceptable. Rough road surface is expected, mud and sand are possible but passable. Rocks up to 6 inches in diameter, loose surface, shelf roads wide enough for passing or pull-offs.
- Rating 4 - High clearance 4WDs are recommended, though most stock SUVs are acceptable. Rough road with rocks greater than 6 inches but with a reasonable driving line is expected. Negotiable mud patches, deep sand requiring lower tire pressures, up to 12 inch deep stream crossings, substantial sections of single-lane shelf road, moderate grades and sections of moderately loose surface are all possible.
- Rating 5 - High-clearance 4WDs are required. Rough, rutted surface, rocks up to 9 inches, mud and deep sand requiring experienced driver, 18 inch stream crossings are expected. There may be traction problems on steep sections, and shelf roads with steep drop-offs or tight clearance (for an SUV width vehicle) between rocks or trees.
- Rating 6 - Trail is for experienced drivers only and are potentialy dangerous due to large rocks, ruts, terraces, stream crossings greater than 18 inches involving rapid currents or unstable bottoms or difficult access. There are also steep slopes, loose surfaces, narrow clearances, narrow shelf-roads with steep drop offs and possibly challanging surfaces.
- Rating 7 - Skilled, experienced 4-wheel drivers only. Very difficult trails with steep grades, loose surfaces, large rocks, deep ruts, and/or tight clearances. Winching over mud, sand or ruts is not unexpected.
- Rating 8 - 10 - There is likely damage to stock vehicles at this level and the trail may be impassable. Highly-skilled, experienced driver is required. These are largely beyond the scope of these maps.
- General - Assumption is that "you are not a serious four-wheeler, but someone traveling in a stock, high-clearance 4-wheel-drive (4WD) vehicle with all-terrain tires and a transfer case with high and low range.
- Easy - The trail is a cruise that probably won't require using 4WD unless conditions deteriorate.
- Moderate - The trail is slower going using 4WD at least occasionally, with rough spots, possible stream fordings, ruts, etc., but little or not technical terrain.
- Difficult - Trail with at least some technical four-wheeling, rough and slow going in 4WD/low range, and the possibility that you will scrape the undercarriage or body panels.
- General - Trail difficulty is both subjective, changeable and un-predictable. You are sole judge of trail's condition on the day you drive it. If any part of the trail is difficult, the entire trail is rated difficult. Read each trail description carefully for specific details. Funtreks displays "photo-descriptions" of each rating at their Photo Gallery. In this case, a picture says a thousand words!
- Easy - Gravel, dirt, clay, sand, or mildly rocky road. Gentle grades.Water levels low except during periods of heavy runoff. Full-width single lane or wider with adequate room to pass most of the time.Where shelf conditions exist, road is wide and well maintained with minor sideways tilt. Four-wheel drive recommended on most trails but some are suitable for two-wheel drive under dry conditions. Clay surface roads, when wet, can significantly increase difficulty or may be impassable.
- Moderate - Rutted dirt or rocky road suitable for most sport utility vehicles. Careful tire placement often necessary. Four-wheel drive, low range, and high ground clearance required. Standard factory skid plates and tow hooks recommended on many trails. Undercarriage may scrape occasionally. Some grades fairly steep but manageable if dry. Soft sand possible. Sideways tilt requires caution. Narrow shelf roads possible. Backing may be necessary to pass. Water depths passable for stock high-clearance vehicles except during periods of heavy runoff. Mud holes may be present especially in the spring. Rock-stacking maybe necessary in some cases. Brush may touch vehicle.
- Difficult - Some trails are suitable for more aggressive stock vehicles but most trails require vehicle modification. Lifts, differential lockers, aggressive articulation, and/or winches recommended in many cases. Skid plates and tow hooks required. Body damage possible. Grades can be steep with severe ground undulation. Sideways tilt canbe extreme. Deep water crossings possible. Shelf roads extremely narrow; use caution in full-size vehicle. Read trail description carefully. Passing may be difficult with backing required for long distances. Brush may scratch sides of vehicle.
- Class I - Semi-improved road, recieving little or no maintenance, over which you can drive a standard passenger car with little fear of damaging the undercarriage. Their publication company (Track and Trails Publications) has a photo description of what they call the Mitchell Scale. In this case, a picture says a thousand words!
- Class II - Road might have a high center, or an occasional rock sticking up, either of which could cause problems for ordinary passenger cars. Possibly able to be negotiated by a skilled driver operating a low-slung automobile, however two-wheel drive vehicles with higher ground clearance than most passenger cars is higly suggested. Four-wheel drive and dual range gears are not needed.
- Class III - Possibly very rocky, very sandy, or very steep. Four-wheel drive may be required. A transfer case with low range gears and locking axles is not needed. Unless they are excessively wide, most off-the-shelf SUVs and pickups, even with novice drivers, should be able to handle this road without any vehicle damage.
- Class IV - Unsuitable for most stock SUVs and recommended only for fully experienced drivers. 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 which can be easily deflated and inflated on the trail. Minor vehicle body damage could occur. An outside spotter may be needed.
- Class V - Extremely difficult and unsuitable for stock vehicles or even moderately experienced drivers. 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. Again, look at the photos of this rating: Mitchell Scale.
- Class VI - Extreme and hard-core. In addition to 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!
Adler Publishing System (Designed with SUVs in mind) -
Tony Huegel Utah Byways (Designed with SUVs in mind) -
Charles A. Wells FunTreks, Inc. -
Track and Trails Publications: The "Mitchell Scale" -
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