It's okay, the pressure's off

"I told you we should have lowered the tyre pressure some more."

Some 4WD trainers reckon deflating tyres is one of the worst sins an off-roader can commit. But go out with some tough club guys and anyone running more than 6psi is a pansy. The truth, as usual, lies somewhere between the extremes. Trainers often argue that dropping pressures at the start of a trip potentially uses your "get out of trouble free" card before you even get going. Extra grip offered by the bulging and elongated tread may lure the driver into trickier situations than his vehicle and/or skill level can handle. And with the pressure already dropped, it may not be safe to lower it further when running tubeless, as most 4WDs are. The tyre may come off its rim, causing more trouble than the vehicle and its occupants were already in. Trainers are also aware that many 4WDs come with fairly low profile tyres whose "short" sidewalls are likely to part from the rim after a much more modest pressure drop than, say, "tall" 75- or 85-series rubber.

Hard-core enthusiasts, on the other hand, want maximum traction and will run the lowest pressure they can get away with. They will normally run tubes and maybe beadlockers to achieve this. I've never had beadlockers, but used to run my tubed tyres as low as 6psi on the Land Rover when conditions warranted it. The grip was amazing. Usually, I found 16-17psi satisfactory for a rutted and muddy track. Many drivers, myself included, also like to drop pressure for off-road comfort. Rutted tracks can give a jarring ride at street pressures; going down to about 24 is wonderfully smoothing.

Dropping pressure for sand driving is common, but only once or twice have I needed to go really low, like below 12psi. Running in the 20-24psi range usually does the trick and often it's not necessary to go anywhere near as low. However, there's more to good sand driving technique than just losing air.