How It Works: The Trailhead Deflators use a simple spring and check valve with a set screw at the top to set the preload, which adjusts the pressure. Setting the pressures on the Trailhead Deflators takes a little bit of work since they are set internally, but once they are set you don’t have to worry about the pressures accidently getting changed.
Installation Notes: One thing that we noticed with the Trailhead Deflators is at low pressures you cannot manually start them, as you can with the Staun and Smittybilt deflators, because the entire mechanism is internal to the product. The tradeoff is that the Trailhead Deflators are less prone to becoming stuck due to dirt or sand getting into the mechanism.
Pros: Can use while driving, simple design, small and light, lifetime warranty, come with lots of extras.
Cons: Require Allen head wrench to adjust (included), cannot manually start at low pressures.
Our Take: The Trailhead Deflators are the only deflators that allow you to drive while you air down.
How It Works: Staun offers brass deflators that use a plunger and a spring, with a collar that sets the preload of the spring, which in turn changes the pressure that the Staun deflators automatically stop at. A jam nut keeps the pressure set, but be sure to crank it down or it is easy to accidently alter the pressure.
Installation Notes: We found the Stauns comparatively difficult to set all to the same pressure without some fine-tuning. Once they were set, they were easy to use, just screw them on and walk away. Staun does not endorse leaving the deflators on while you drive, but we did this (at low speeds) without any issues.
Pros: Easy to adjust, compact, well made, manual start, easy to transfer between vehicles.
Cons: Difficult to set to the same pressure.
Our Take: Similar in function to the Trailhead Deflators and Smittybilt Tire Deflators. Easier to accidently change the pressure than the Trailheads, but can manually start at low pressures.
TeraFlex Air Deflators
How It Works: Constructed from zinc-plated steel, the TeraFlex Air Deflators take the work out of pushing down the valve core by doing it for you. Just screw them on to your valve stems and they let out air until you remove them. You can easily put a gauge (not included) on top of the deflator to periodically check pressure.
Installation Notes: These are as simple as it gets. No setup, nothing to fail (unless you cross-thread them). Just don’t get too involved swapping stories to your friends at the start of the trail or you will end up with four flat tires.
Pros: Compact, inexpensive, double as a key chain, nothing to stick or fail.
Cons: Do not automatically stop at a given pressure.
Our Take: TeraFlex doesn’t tout their deflators as being fast, but they do simplify the air down process at a very reasonable price.
Extreme Outback Products Mil-Spec Multi Choice Deflator
How It Works: The premise behind Extreme Outback Products’ Mil-Spec Multi Choice Deflators is the same as the Trailheads and Stauns. While not as compact as those designs, the Mil-Spec deflators add an integrated adjustment feature that is easy to read and use. No guessing about what pressure you are running, even if you don’t have a gauge handy.
Installation Notes: This was the easiest of all the products to use. No set up time, no need to keep an eye on the process. Just turn the dial to set the pressure and screw it on to the valve stem. One issue we found with our testing, which was performed at 5,000 feet in elevation, was that the pressure settings were slightly off as a result of the altitude. This is something to keep in mind if you are airing down at the top of Black Bear Pass.
Pros: Easy to adjust to different pressures to suit the terrain, easy to transfer from one vehicle to another.
Cons: Expensive, large, and bulky.
Our Take: The Mil-Spec Multi Choice Deflators are the easiest to adjust and are well made, but these features come at the highest price in our test.
Slime Four-Way Valve Tool
How It Works: This tool ejects the valve core at a high rate of speed into the dirt if you are not careful. By the time you find the valve and wipe it clean you might be left with no air in the tire. Getting the valve core back in can be a challenge while the air is escaping.
Installation Notes: We simply pulled the valve core out and let the air out until we got to 10 psi. Without a secondary location to hook up a gauge though this is not always easy on the trail, but we found that escaping air changed pitch as the pressure got lower. We were surprised to find that this method was no faster than the ARB or Currie gauges, which we assumed caused some resistance.
Pros: Fast, dirt cheap, easy to transfer between vehicles.
Cons: Prone to losing valve cores, difficult to stop airing down at desired pressure.
Our Take: As cheap and simple as it gets if you are not picky about exact pressures, but remember to pack a few extra valve cores.