Four wheeling with your tires at highway air pressure results in extremely poor traction off road.  This was one of the first lessons I learned 7 years ago on my first off road adventures.  A fellow 4WD driver took the time to explain the advantages of reducing air pressure for increased traction.

The basic concept is that as tire pressure is decreased it  allows the tire to flex more; as the tire sidewall flexes it increases the tread contact surface area.  The tread on the tire will also wrap around the rocks and terrain to grab a hold and give the vehicle traction.

Tire Air Down Increase Traction

Increased traction off road helps the driver to finesse over obstacles rather than using speed or spinning the tires.  The increased control keeps the vehicle moving forward in the proper direction.  This will help limit the possibility of damaging your vehicle or breaking parts.

How much air is enough?  In most cases, less is more; meaning that it’s best to run with the lowest pressure possible.  When airing down your tires wait until you see the tire sidewall start bulging out while sitting on level ground.  This will be a good pressure to start with; target range is 6-15 psi.  Then test it and air down further as needed.

Some tires with thick sidewall construction will need less air pressure than tires with thin sidewalls.  For instance, Super Swamper TSL or Bogger tires (thick sidewalls) may perform best at 6-8 psi; while a BFGoodrich AT (thinner sidwall) may perform well with 12-15 psi.

Tire Air Down Sidewall Flex

Will too little air pressure be an issue?  Yes, it certainly can be.  The primary concern is that the tire may come off the rim if the pressure gets too low.  This generally happens when a rock or stump pushes the tire sidewall away from the rim.  You’ve probably seen the Extreme Off Road Vehicles with beadlock wheels.  The beadlock wheels bolt the lip of the tire to the rim keeping it from coming off the rim at low tire pressure.  In most cases beadlock rims are not necessary.  I’ve had my tire come off the rim once in 7 years of 4wheeling.  Just exercise a bit of caution.

Tire Air Down Off Rim

Quick note:  Be sure you or someone with you has an air compressor and carry a spare tire.  Sometimes the unexpected happens and having the proper recover equipment is essential.

Click on the link below to discuss tire pressure on the forum.

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Post edited 4:25 am – March 1, 2009 by Ah Yeah

Here's the tire pressure that I've found to work well….

36″ Super Swamper TSL on 10″ wide wheels – 6-8 psi in for all conditions off road (these tires are very ridged) – never lost a bead

35″ Wild Country XTR on 8″ wide wheels – 9-10 psi for trails & 4-5 psi in deep snow – lost a bead once

33″ Toyo MTs on 8″ wide wheels – 10 psi on trails (worked great in snow too) – never lost a bead

Post up the tire pressure you prefer with your tires!

When I was running 35″ Toyo's, I ran them down to 8 psi on trails, and down to 5 psi on snow.  They were mounted on 8″ wide steelies, and never had any problems.  The 36″ TSL-SX's that are on the XJ, are mounted on 8″ wide beadlocks, and I have ran them as low as 4 psi, but most trails I ran them at 6psi.  Never had any issues, and worked excellent.