How Quick Can You Go Low?
The tradition of airing down at the trailhead is almost as old as four-wheeling itself. Why? Letting air out of your tires allows the tires to conform to the terrain for improvements in traction and ride quality. While the benefits are universal for all tires and vehicles, the method of getting the air out of the tires is not. We rounded up 10 different tire deflators and monitored how fast they could air down a 37-inch BFGoodrich Krawler T/A KX from 40 psi to 10 psi. More than just how fast the deflators worked, we also evaluated factors such as build quality, price, and ease of use.
The basic functionality falls into three groups: those that depress the valve core, others that remove the core from the valve stem, and products that take the original valve core out of the equation altogether. The emphasis on the valve core is not an accident. This is what retains air in your tires until you are ready to deflate them, and we found it to be a limiting factor with regards to speed. The Trailhead, Staun, Extreme Outback, and Smittybilt deflators screw onto the valve stem and depress the valve core, then the air pressure must overcome a spring to let air out. As a result, they are very fast at high pressures and slow down as pressures decrease. In the case of the Smittybilt, it was still allowing air to slowly escape after 18 minutes, but had not yet reached our target pressure of 10 psi.
The ARB and Currie gauges remove the valve core and speed up the process considerably. The Slime valve core tool removes the core as well, but it doesn’t capture and retain the valve core like the ARB and Currie products, nor does it allow you to monitor the pressure like the other two. The Power Tank Monster Valves and Rimrock Mountain Supply Rapid Air Down Stems circumvent the stock hardware altogether with auxiliary valve stems that you add to your wheels. Both have holes in the body of the valve stem beneath the core that release air quickly once uncovered. They were the fastest products in the test.
Note that the testing times did not take into account setting the correct pressure of the auto deflators, which is necessary on the Trailhead, Staun, and Smittybilt products. This is not a trivial process and best done in the garage before you head out the trail. Trailhead cleverly recommends using a wheelbarrow tire to set the pressures, since the volume is small and easy to air up and down quickly. Once you dial in the desired pressure these products are ready to air down all four tires when you reach the trail. By comparison, the ARB and Currie deflators require no setup, but they are only capable of airing down one tire at a time. So while they are faster in our single tire test, the numbers become more comparable when airing down all four tires. Consider this when reviewing the results table and drawing a conclusion about which product is best for your needs.
ARB E-Z Deflator
How It Works: The ARB E-Z Deflator is gauge and tire deflator all in one. But unlike most “all-in-one” products, this one actually excels in both areas. The deflator functions by removing the valve core from the stem and capturing it within the brass housing. Then you slide a collar- up to release air, down to close the system and check the air pressure.
Installation Notes: The tool must be entirely threaded onto the valve stem to ensure that the core can be removed without damaging it. We were curious about the accuracy of the gauge, but found it to be within two pounds of the liquid-filled Power Tank gauge we used for reference in all of our tests.
Pros: Fast, reasonable price, integral gauge makes it simple to check pressure, can easily run different pressures to suit the terrain, easy to transfer from one vehicle to another.
Cons: Only capable of airing down one tire at a time, interference issues with some wide beadlock rings, cannot be used while the vehicle is moving.
Our Take: This deflator strikes a near perfect balance between speed, price, and ease of use.