Harry Wagner
Contributor
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.
Click to enlarge the chart.
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.
Trailhead Deflators
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.
Staun Deflators
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.
Smittybilt Tire Deflators
How It Works: A spring inside the machined brass housing must be overcome by the tire pressure in order to allow air to escape from holes in the body of the deflator. 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: Smittybilt’s packaging states “Get The Original,” but they look just like the Staun deflators. In fact, some of the components even interchange! The Smittybilt deflators do not come in various pressure ranges, and the spring is noticeably stiffer than the Staun. As a result, small changes make a big difference in pressures, making it difficult to set all four deflators to the same value. Smittybilt does not endorse leaving the deflators on while you drive, but we did this (at low speeds) without any issues.
Pros: Low price, manual start, easy to transfer between vehicles.
Cons: Difficult to set to the same pressure, poor fit and finish, small adjustments make big changes.
Our Take: The price is right, but be prepared to make some compromises for that value.
Currie EZ Deflator
How It Works: The Currie deflator functions the same as the ARB deflator. In fact, near as we can tell they are exactly the same product.
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 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.
Power Tank Monster Valves
How It Works: Instead of relying on the stock valve stems, Monster Valves add a second valve stem to the wheel that are larger than stock. This aluminum valve stem has a threaded collar on it below the valve core. Simply unscrew the collar to uncover the holes in the valve body and begin deflating.
Installation Notes: In order to install Monster Valves you have to drill and tap a hole into each of your wheels. Power Tank has a video on its website that explains the installation. You do not need to dismount the tires, and Power Tank suggests mounting the Monster Valve 180 degrees from the factory valve and inboard on the rim in order to keep it protected from harm. Make sure that you drill and tap them straight, you only get one shot! The Monster Valves also come with a Monster Chuck to air up with. Airing up from 10 psi to 40 psi through the standard valve stem took two minutes for our Krawler, while the Monster Chuck on the Monster Valve only took 1:20, a 50-percent improvement.
Pros: Blistering fast, allows you to check the air pressure with the original valve stem while airing down with the Monster Valves, only system that allows faster airing up.
Cons: Have to drill holes in rims, could get torn off on the trail, cannot easily transfer between vehicles.
Our Take: Monster Valves could be the perfect choice for those who have 37-inch and larger tires and still drive on the street.
Rimrock Mountain Supply Rapid Air Down Stems (RADS)
How It Works: The RADS are similar in premise to the Monster Valves, with a collar on the outside of the valve stem that has holes beneath the valve core. Turn the collar to expose these holes and air comes out at a rapid rate. Unlike the Monster Valves, the RADS use a traditional-sized valve core.
Installation Notes: Rimrock Mountain Supply recommends adding a second hole to your rim for the RADS, so we did this for our test. We had an issue with the valve stem being too long for our relatively thin steel wheels, so we had to cut the bottom threaded portion of the RADS in order to allow the tire bead to pass over the valve stem.
Pros: Fastest product in our test, low profile, allows you to check the tire pressure with the stock valve stem while airing down through the RADS.
Cons: Requires dismounting tires from wheels and drilling holes in wheels, fitment issues on some applications, cannot easily transfer between vehicles.
Our Take: We recommend using them instead of traditional valve stems rather than in addition to, just to simplify installation. The limitation is that you cannot check the air pressure while deflating, but we would just get close and then use the traditional valve core to fine-tune the pressure.
