In case you haven’t already spotted it, Jonathan Hanson, a co-founder of the Overland Journal and now co-director of Overland Expo, writes an excellent blog called Overland Tech & Travel.
He recently posted an in-depth article on airing down, in which he explains the ins and outs, as well as reviews the most well-known tools to help with the job. He covers, among others, the ARB E-Z Deflator (a valve core removal tool coupled with a pressure gauge), a set of second generation Staun deflators, and the Mil-Spec deflator from CB Developments.
Both the Staun and CB Developments deflators screw on to the tire valve and stop deflating at a predetermined pressure. The cutoff pressure for the Stauns (they come as a set of four for about $80) has to be set using a tire inflated to the desired cut-off pressure (from 3 to 50 psi). The CB Development deflators (sold individually for about $100) can be dialed in to the desired pressure directly (from 10 to 20 psi). He covers deflators by Trailhead as well.
The article is well written and the products sound like they were well tested.
Photo: Airing down on our way to Laurel Lakes, near Mammoth, California