Words of Wisdom: “In the end, an ounce of prevention is worth a pound of cure. If you are in any way unsure of the way ahead, stop the car and walk the route to determine grade, clearances, and firmness.” – USExplorer1)
“By far the best bang for your buck is a 12 volt air compressor and air down your tires. Just airing down your tires to 10 pounds will get you unstuck an amazing amount of times. It should be number one on your list for taking your van in rough country.” – akrvbob2)
Four wheel drive (4WD) is the most common concept in increasing traction. In a 4wd system both the front and rear axle receive power. It is common for base-model 4WD vehicles to have “open diffs” (see below). While it has definite benefits, 4WD generally costs more to purchase, insure, maintain, and lowers MPG.
In trucks and cargo vans a two wheel drive (2WD) vehicle only receives power at one axle, usually the rear axle.3).
All Wheel Drive (AWD) is a usually a full-time system found in cars and light SUVs. It has limited capabilities offroad, but can be nice for snow and slippery flat surfaces. It is NOT a replacement for 4WD.
The usual type of stock differential is an open differential, a simple arrangement that is inexpensive and works well on surfaces with sufficient traction. The problem is that when traction is not always sufficient; in those situations one tire spins, one tire is stationary, and the vehicle is stuck.
One way to meet this challenge is to use a locking differential (LD). A locker can be changed, electronically or by air pressure, between two states:
Another way to meet the challenge is to use a limited slip differential (LSD), whether physical or virtual. A physical or traditional LSD uses clutch packs or worm gears to limit the difference between wheel speeds. A certain amount of spinning of one wheel relative to the other results in a clamping effect which can either lock them together or limit the difference, as in a torsen type LSD. Some GM vehicles came stock with a clutch type G80 limited slip; a VIN decoder or vehicle info tag will reveal this information.
The sensors and controls associated with ABS brakes allow for virtual forms of limited slip. A subset of Electronic Traction Control (ETC), Brake-lock differential (BLD) can control wheelspin with an otherwise-open diff by selectively braking the wheel that is spinning. In addition to stability controls that will not be addressed here, many ETC systems can be configured on the fly:
Tires on the drive axles can make a major difference on a vehicle's ability to reach secluded camping spots. All terrain tires favored on CRVL are:
Having a lower tire pressure is like wearing a snowshow. – BleepinJeep12)
Airing down works because:
In sand, airing down to pressure of 12-15psi is common, with some going down to 8psi (with bead locks). This video shows the difference between full pressure and 15psi in wet sand. This video shows the difference between 22psi and 10psi in dry sand
In loose rock, air down somewhat less so the sidewalls are less likely to be damaged by sharp rocks. This video shows the difference between 30psi and 5psi.
A snatch strap is a nylon strap that has some stretch in it. Not only does this greatly reduce the violence of pulling someone out, but it also allows the rescue vehicle to get keep forward momentum when the strap pulls tight. It is a rubber band or bungie cord effect, only much stronger.
Before you get stuck:
When you are stuck:
This Australian video shows excellent safety procedures.
Recovery Mats/Boards such as Max Trax are a good idea to carry with you at all times if you expect to be going off pavement. They're a lot cheaper than a tow truck.