Airing down the tires is a universal chore for fourwheelers but these days we're spoiled for choice when it comes to devices for making this job easier. Among these products there are two main systems: automatic deflators, and valve core removers. Automatic deflators are, as the name implies, automatic. You screw them onto the valve stems and they release air until a pre-set pressure is reached. With valve core removers, you use them to remove the valve core which lets the air out so quickly that you must stay there to monitor the pressure, lest you end up under-inflating your tires.

The Trailhead Deflator is the original automatic tire deflator. Each kit consists of four lightweight, aluminum deflators; an allen key for adjusting the deflators; a pressure gauge; a pressure reference chart; and a carrying case. Unlike some of the other automatic deflators, the Trailhead units are significant in that they are very good at retaining their pre-set pressure. Thanks to their internal adjuster, they don't loosen up and end up airing down your tires to the wrong pressure. Their other notable characteristic is that when you screw them into the valve stem, they immediately start releasing a strong flow of air. Some of the other deflators are a bit anemic in this regard.

Myself, I'm a supporter of the remove-the-valve-core philosophy of airing down your tires, mainly because it's fast. But testing these Trailhead deflators has made me reconsider my position. I did a comparison between the Trailheads and my ARB deflator. The test subject was a 36x13.5 IROK aired up to 25psi. First, I aired it down to 12psi (the default setting on the Trailhead deflators) and timed the process. Then I re-inflated it back to 25psi and aired it down using the ARB deflator.

Trailhead

ARB

It took about 3.5 minutes from the time I started screwing on a Trailhead deflator to when it reached 12psi and automatically stopped releasing air. Using my ARB deflator, it took about 1 minute, from the time I started screwing on the deflator to the time when it reached 12psi. Some of that time included me stopping and checking the air pressure, which, of course, is something that the automatic deflator avoids.

Clearly, the ARB valve core remover deflator is much faster. Much faster, that is, when deflating one tire. But when you consider the fact that you can attach the Trailhead deflators to the other tires while the first is deflating, the difference shrinks. As well, you could attend to other trail-prep activities such as unhooking your sway bar or locking in your hubs while the Trailhead deflators work. Meanwhile, with the ARB deflator, you're pretty much stuck there, squatting by the tire, to make sure that you don't under-inflate your tire.

This makes the Trailhead deflators sound like the obvious choice. But there are a couple of hitches. The main one is that the manufacturer recommends that your tire have twice the pressure of the target pressure. In other words, for the Trailhead deflators to reliably air down your tire to 12psi, it should start from a pressure of 24psi or higher. The second issue is that these deflators only air down to a specific pre-set pressure. Switching to a different pressure involves using the allen key to change the shut-off point. Each turn changes the pre-set pressure by around 1.5psi, but it's not absolutely accurate. Some trial-and-error is needed. So in the scenario where you air down to, say, 15psi for a softer ride on a gravel road, and then want to air down to 8psi when you reach the trailhead, the Trailhead deflators aren't the most practical choice.

If you tend to use the same pressure all the time, the Trailhead deflators would be a very good tool to keep in your 4x4's toolbox. They're small, lightweight, and turn the tedious chore of airing down into an easy and automatic process. They're also made in the U.S.A. and come with a limited lifetime warranty. They come in two pressures ranges: 5-20psi (red), and 15-40psi (blue).

I got mine from Roving Recovery: www.rovingrecovery.com/index2.htm

...lars