When heading offroad in the desert, it is important to air down your tires when driving in deep sand. This increases the surface area of your tires, and allows you to “float” on the surface of the sand rather than digging in. It is also important not to stop in areas of deep sand, and keep a steady momentum. When I know that I will be entering an area with deep sand, I pull over and air down my tires. I typically deflate them to around 16 PSI. To help with this, I use some automatic tire deflators that screw onto the valve stems. They will cut off the airflow as soon as the pressure reaches the calibrated PSI.
Airing down your tires also helps with washboard roads. It smooths out the ride and allows you to keep control of the vehicle. I don’t go all the way down to 16 PSI for washboard conditions though. Typically, something in the mid 20PSI range is plenty enough. When traveling over areas with sharp rocks, airing down your tires will also help avoid punctures. It is like trying to pop a balloon that is over filled with air, versus one that is partially deflated.
The dilemma arises when you return to pavement and need to fill your tires back up. The inexpensive cigarette adapter compressors will do the job, but they are slow. I had one that took about 15 minutes to air my tires back up to street pressure. 15 minutes x 4 tires is a long time.
I invested in a CO2 tank setup — They are expensive, but worth every penny. Instead of waiting 15 minutes for each tire, it takes me 30 seconds. For every 2 seconds, the tire is inflated 1 PSI. You could build one of these yourself by purchasing all of the components separately, but I am not very knowledgeable in this department. I left it to the experts, and purchased a Powertank setup.
I get the tank filled up for about $20 by a local gas and welding supply company. Each tank lasts several trips.
I store the tank in a Lightware case that was originally intended for a 400mm 2.8 lens with body attached. It’s a perfect fit! I store the tank behind the passenger seat in a void that was created by removing the rear seat. When I am not on a shooting trip, I still keep the tank with me. It comes in handy if my tires ever run a bit low.
Here’s a video that shows some conditions near Coyote Buttes South that require airing down.