I usually like to drive fast enough to essentially skip across the tops of the washboard rolls which seems to be between 30-35mph. In sand or on rocks reducing your tire pressure gives you a larger tire tread contact patch and softer, more flexible and pliant face and sidewalls which help grab hold off, roll over or push through those sorts of obstacles. With properly deflated tires this can give you a relatively plush ride instead of the usual teeth-jarring, bone-rattling or wheel spinning.
For quick tire deflation duties I use a set of Coyote Automatic Tire Deflators.
They received good, consistent reviews on Amazon, were a step cheaper than the Stahn option and they are made in the US. I chose the model with the 3-50 psi adjustment range.
They’re quite small (36.7mm X 15.9mm/1.445″ X 0.625″) but feel nice and solid. Why? Well that’s because they are constructed of 100% solid brass. They come set from the factory for ~ 12 psi. Since I don’t have bead locker wheels I was apprehensive about airing down into the teen or even single digit psi range so I immediately swapped the factory installed silver springs (5-20 psi) for the included red springs which have a 5-50 psi range. During our first year of having the deflators we paid close attention to what PSI each of them “popped” closed at and repeatedly adjusted them to where all four ended up in the ‘teens and one pair was a few pounds higher than the other pair. The lower PSI pair (I wrote 1-4 with a Sharpie on them) usually ends up at 12-14 and I put those two on the front axle. The other two stop from 16-18 and I use those on the rear axle just because I think that the heavier half of the vehicle can use that extra “uumph” especially when we are bouncing around offroad. Depending on temperature and altitude those PSI numbers can vary +/- 5 PSI. After a couple of tries adjusting them, re-inflating the tires and seeing where they stop I’ve gotten them all to stop deflating at under 20 psi, warm, at sea level. If I am really in a fine-tuning mood I then take out my ARB pressure gauge and drop the pressure to what, exactly I think might be optimal. I never, ever, take out my ARB dual compressor just to add pressure for an offroad excursion. I use that strictly for the “Big” air-up after an extended run in conditions that warranted the previous air-down. It takes a couple tries but once you fine tune and set the psi where you want it you can assume it will just always work as you expect. They work incredibly easy. Twist on, pull ring, tires deflate to set pressure. Remove.
By the time you are done putting on the fourth one, the first one is usually done or close to it.
There is obviously some wiggle room when you factor in substantially higher elevations and/or wild temperature swings. I’ve used them from sea level to 7800′ or so and from 70 deg F to around 0 deg F and am seeing, at most, a 5 psi swing range. They still stop at the same psi as one another regardless of the environment though and predictable and consistent is good.
After the fun we’ve had being aired down the last thing we have to do when reaching a paved road is to re-inflate my KO2’s and we do that with our
MV50 Compressor (we now use an ARB Dual compressor instead.)