Overlanding upgrades often include expensive add-ons like lockers, a winch, or a new suspension. But there is a simple upgrade that will improve your vehicle’s traction, and it doesn’t have to cost a penny. Try airing down your tires.
Traction starts and ends at your tires and improves your vehicle’s off-road capability immensely. If your tires don’t have traction then it doesn’t matter how advanced your vehicle’s traction control system is or how much money you’ve dumped into other modifications. Airing down, or letting air out of your tires to reduce the pressure, increases a tire’s contact patch on the ground. Under the right conditions, airing down provides more traction and a smoother ride.
Read on to learn how to gauge tire pressure, the different methods for airing down, tools to make it easy, and how to air back up when you hit the pavement.
How Low Can You Go? Airing Down Your Tires
First, let’s talk about air pressure in general. There’s no hard and fast rule on what pressure you should air down to, and most tire manufacturers won’t give recommendations for liability reasons. Choosing how much air to let out of your tires will largely depend on your specific vehicle and tires, what street pressure you run, and your driving preferences. In general, lighter vehicles, like a Subaru Forester or Jeep Wrangler, can run lower air pressures off-road than a larger vehicle.
The best guide I’ve found is from Jonathan Hanson, a writer and adventurer who co-founded Overland Expo and Overland Journal. As a rough starting place, Hanson recommends dropping pressure by 25% for general off-road driving on rough dirt roads, washboard. and moderate trails, 30-35% for traction on slick-rock and difficult trails, and up to 50% for surfaces like very soft sand.
Let’s use my 06 Power Wagon as an example. I run about 44 PSI in the front tires and 54 PSI in the rear on the street, and going by the guide above I should be running around 30 PSI in the front and 40 PSI in the rear on most easy off-road terrain. I can go as low as 22 PSI upfront for deep sand. Remember, that’s just a starting point: figuring out the best pressure for your rig will take some testing to see what works best.
Tire Choice
Before diving into the nitty-gritty on how to air down, let’s talk about tire choice. Tires are the most important piece of the traction puzzle, and the tires you put on your vehicle can make the difference in how far down the dirt road you venture.
All-terrain tires work best for overlanding, offering a durable tread compound and burly sidewalls. These elements help protect the tires from punctures and other damage while driving off-pavement and also makes them better suited to airing down. When you reduce the pressure in your tires, the sidewalls flex, providing more tread in contact with the ground. Stiffer, stronger sidewalls allow you to air the tire down more with less worry about damage.
The Toyo’s Open Country A/T III, which I run on my truck, or BF Goodrich’s All Terrain T/A K02, provides an upgrade in off-road traction compared to the stock all-season tires that come on most crossovers, SUVs, and trucks. Thanks to a more aggressive tread pattern that has more bite, these tires perform well in loose dirt and rocks. Despite being more aggressive, they still work very well on pavement and remain quiet on the highway.
Three Methods for Airing Down
The Cheap Method
Tire gauges, like the small, pen-shaped devices that are available at most gas stations, will measure PSI and let air pressure out of your tires at a low cost. To use the tire gauge, depress the valve core and monitor the pressure gauge until you let the desired amount of air out of your tire, and repeat the process for each tire. You can also use a stick or other slim object like a pen if you’re in a bind, being careful not to let too much air out.
The biggest drawback of the tire gauge method is that, depending on your tire pressure, it takes a long time and you’ll only be able to deflate one tire at a time. There are several tools to consider to make it easier on yourself.
The Fast and Precise Method
To reduce time spent airing down, many overlanders use ARB’s E-Z Deflator. This tool removes the valve core (the mechanism that prevents air from escaping the tire) and lets you decrease pressure from your tire faster, saving you a ton of time at the trailhead. While you can remove the valve core yourself, you risk losing the valve core and ending up with a flat tire. The E-Z Deflator encases the valve core inside of it, ensuring you won’t lose it, and uses a built-in pressure gauge so that you won’t miss your mark when airing down. Unfortunately, using this method means you still only deflate one tire at a time.
The Automatic Method
Use automatic tire deflators to let the air out of more than one tire at once. Automatic tire deflators screw onto your tire’s valve stem and automatically let the air out of the tire until you reach your target pressure. First, you need need to set up your target tire pressure manually and then simply screw them on to your valve stems and let the tire deflators take the air out for you. When your tires reach the desired pressure, the deflators shut off and stop letting air out. This means you’re free to do other tasks and that you won’t have to worry about checking tire gauges. Here’s a great video on how to use automatic tire deflators. While at a higher price point this set from Staun has been proven over the years and is highly recommended.
If you want to make airing down even easier, consider another tool called an Indeflate. It’s a simple device with two air hoses that automatically equalizes the pressure in two tires and allows you to deflate or inflate two tires at once. It still takes the same amount of time that it would for your compressor to inflate two tires, but this tool will remove one step and pair down your airing down/up process even more.
Airing Back Up
Airing down provides a much more comfortable ride off road and gives you better traction, but running low pressure on the pavement is unsafe and robs you of fuel economy. Underinflated tires heat up on the pavement, especially at highway speeds, and are subject to blowouts and failures, so you must fill your tires back up when you leave the dirt. Driving slowly to a gas station with an air compressor works in a pinch, but you’re better off carrying an air compressor in your vehicle.
There are many portable air compressors on the market designed for automotive use. I recommend a high-quality compressor that connects to your vehicle’s battery for maximum filling capacity. For filling up larger off-road tires you should look at one from VIAIR or ARB – like VIAIR’s excellent 400P. Avoid buying one of the small compressors that plug into your car’s 12v outlet; they just don’t have the power to fill up tires quickly, and once you realize how long it takes it’s unlikely you’ll ever air down again.
When you choose an air compressor, pay attention to the CFM (cubic feet per minute) rating and duty cycle. The CFM number refers to how much volume the compressor can move, and the duty cycle refers to how long the compressor can run before needing to shut down. I’ve used VIAIR’s 400P Automatic for years with great success, and it will fill one of my truck’s 35×12.5in tires from 15-30PSI in 2 minutes and 45 seconds.
Make Airing Down Easy and You’ll Do it More
After swapping on a set of all-terrain tires, airing down provides the biggest performance boost you can give your rig. The time it takes to air down prevents many people from skipping this step, despite the many benefits. With that in mind, make airing down easy and you’ll be more likely to do it. A set of automatic tire deflators and a good air compressor will accomplish that goal.