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TRAIL RATING
Arizona State Association of 4-Wheel Drive
clubs, Inc.
NUMERICAL 4WD TRAIL RATING
SYSTEM
2-WHEEL DRIVE
1.0 All-weather high speed paved or graded dirt or gravel
road, regularly
maintained, with excellent drainage. 4WD not needed, even in wet weather.
Speeds of over 40 mph can be achieved. Passenger cars acceptable.
1.5 Maintained graded dirt road. 4WD not needed except in
wet weather. May
have potholes, dips, and sharp curves. May drain poorly in wet weather.
Speeds of over 10 mph possible. Passenger cars can do, but will have
to
slow down considerably on washouts, etc. due to lack of ground clearance. No
grades over 10 degrees.
EASY 4WD
2.0 Unimproved or rarely graded dirt road; 4WD and/or extra
clearance
occasionally needed at times, with no special driving skills required.
Passengers cars NOT acceptable, due to insufficient ground clearance. 2WD &
4WD trucks with stock clearance are acceptable. Street tires are
acceptable. Day runs are typically 20 miles in length.
2.5 Dirt road graded rarely, if ever. 4WD low range and good
clearance
often needed, with some extra care and a bit of driving experience useful.
Suitable for novice drivers. Speeds often under 10 mph. Street tires
are
acceptable. 2WD trucks NOT acceptable, due to lack of low range gears.
No
grades over 20 degrees.
MODERATE 4WD
3.0 Ungraded road in difficult terrain, rarely maintained. 4WD
low range
and clearance required., with some driving skill and daring useful.
Challenges for novice driver. Suitable for stock 4WD vehicles.
Street
tires are not recommended. No 2WD vehicles, due to lack of traction.
Speeds
often under 5 mph.
3.5 Road or trail in difficult terrain, probably maintained
only by
occasional users. Considerable driving skill and daring needed. Not
recommended for the novice driver. Surface may include wash beds, and,
cinders, lava rock, snow, mud, water, etc. Vehicles with long front
or
rear overhang (beyond the axles) may scrape front or rear bumpers on
wash
crossings, etc. Street tires not acceptable. Approaching the limit of
what
a capable stock 4WD vehicle (with capable driver) can do. Stock 4WD
vehicles usually not recommended. Upgrade to 31" tires, mild lift (1" or
2"), and rear locker or limited slip is highly desirable. Equipment
failure
is usually limited to flat tires. Grades may exceed 20 degrees. Occasional
off camber situation may exceed 20 degrees. Water crossings should be 2 feet
or less in depth. Spotting may be required on the more difficult
sections,
especially for long, wide vehicles. Average speed is 3 mph. A
day run is
typically around 10 miles in length. This is the most common numerical
rating given to 4WD trails. Suitable for mildly modified 4WD vehicles &
moderately experienced drivers.
HARD 4WD
4.0 Trail badly eroded. Off camber situations likely and may
exceed 25
degrees. Grades may exceed 25 degrees. Water crossings can
exceed 2 feet
in depth. Stock vehicles NOT recommended. 31" tires minimum,
(33"
preferred), mild lift & hard locker, (not limited slip), in the rear
probably required. Front locker or limited slip recommended.
Speeds often
under 3 mph. Spotting probably required on the more difficult
obstacles to
avoid body damage. Recommended for experienced 4WD drivers only. Body
damage possible, but unlikely. More likely on long, and/or wide
vehicles.
Equipment failure possible, but unlikely.
4.5 Trail is TOUGH. Big rocks, grades exceeding 30 degrees.
Off camber
situations exceeding 30 degrees. Sometimes, but not always,
best suited
for short wheel base vehicles. (under 105") 33" Tires minimum,
(35" or
larger preferred). 2" to 4" of lift and gearing of 40 to 1
(20 to 1 for
automatics) or lower in first gear, low range probably required. Hard
locker in the rear and limited slip or hard locker in the front probably
required. Speeds often under 1 mph. A day run will usually be 1-3
miles in
length. Body damage likely, but usually can be avoided by very careful
driving and good spotting. Typically 10% of the vehicles on these runs
will
experience major mechanical failure, i.e. driveline or steering failure.
(u-joints, axles, pitman arm, drag link, tie rods, etc.) Usually,
but not
always, these failures are due to improper and insufficiently tested
vehicle modifications or poor (sloppy) driving technique. (Too much gas or
steering pressure) An experienced driver with a
properly setup vehicle can usually avoid most breakage.
5.0 Trail CANNOT be driven the whole way. Winching is required
in at least
1 point on the trail. Water crossings may exceed 2 1/2 feet in depth.
Grades exceeding 40 degrees. The biggest rocks with off camber situations
exceeding 35 degrees. Rollovers possible. Usually only suitable
for short
wheel base vehicles. (under 105") Winch, 33" minimum tires, (35"
or larger
preferred), 3" to 5" of lift, gearing of 60 to 1 ( 30 to 1 for
automatics)
or lower in first gear, low range, and hard locker in both front and
rear
axles probably required. Axle upgrades highly recommended. Speed
continuously under 1 mph. A day run is typically 1 mile in length.
These
trails are typically very hard on tires. 1 spare probably required, 2
spares recommended. Plug kit and/or tubes recommended. Tires with
sufficient sidewall protection (Boggers, Swampers, etc.) recommended.
50%
or greater chance of body damage. 50% or greater chance of major mechanical
failure. Breakage is usually due to excessive torque or torque spikes
on
axles or steering components. Only world class, experienced (5
years +)
drivers with extra money, parts & energy to repair broken vehicles
need
apply.
NOTES
Each .5 increase in the trail rating, doubles the difficulty.
Therefore a
4.0 rated trail is approx. twice as hard as a 3.5 rated trail.
Wet trail conditions can raise the trail rating by .5, and ratings can
vary
(+ or -) by up to .5 from year to year, due to changing conditions.
When evaluating trail ratings and suggested minimum vehicle and driver
experience requirements, please realize that it is possible to drag
any 4WD
vehicle, (or 2WD vehicle for that matter), through practically any
type of
terrain, given enough time, energy and money and effort.
The suggested
minimum vehicle requirements and driver experience levels are based upon the
following assumptions.
1. That the vehicle will be driven under its own power throughout the
entire trail.
2. That no body damage will occur.
3. That the trail will not be altered. (by stacking rocks, etc.)
4. That the trail will be completed in a reasonable time frame.
If these items are not important to you and you wish to participate in a run
with a vehicle or driver experience level substantially below the suggested
minimum requirements, please contact your trip leader as to the
feasibility
of your participation. Remember that the last item "reasonable time
frame"
affects everyone on the run, not just you and your vehicle.
Paint scratches from vegetation on narrow trails can be an issue on any
trail rated 2.0 or higher. While not technically an obstacle, we
realize
that to some participants with newer vehicles this is a concern.
Please
contact your trip leader as to this possibility, and trip leaders inform
your participants as to the probability of this occurring. The
best
defense against this is a good coat of wax, and very careful driving.
Most
scratches on a highly waxed surface will buff out after the trip. Black
paint shows the most scratches, white paint shows the least.
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