How to Air Down Tires for Off-road Driving
One of the easiest ways to make a vehicle perform better off-road is to air down the tires when you leave the pavement. Whether you’re on a short technical trail run or a long overlanding trip, reducing your tire pressure serves at least two critical functions.
First, reducing the pressure in the tire increases the amount of the tire touching the ground, which increases traction. This added grip prevents them from slipping. It also helps them float on soft ground, such as mud, snow, and sand, preventing them from bogging down and spinning in place.
Second, airing down can soften the ride for you and your passengers when you are off-road by allowing your tires to absorb shocks from rough roads and trails.
I’ll go into more detail below, but most tires designed for off-roading can air down to about 15 pounds per square inch (PSI) while traveling off-road without much risk of the tire coming off the rim. If you’re just looking to soften your ride a bit and get some moderate traction advantage, start by reducing your pressure by 5 -10 PSI.
To state the obvious, if you air down, you’re going to need to air back up again, which will require an air compressor. Driving aired-down tires on the pavement can be dangerous.
Do I have to air down my tires while off-road?
No. Letting air out of your tires and reinflating can be a hassle and cuts into trail time. Airing down also puts additional stress on your tires and makes the sidewalls more vulnerable to damage and, at low pressures, the tires are more likely to come off the rim. Only air down as much as you need to and not more.
If you’ll be traveling on relatively mellow gravel or dirt trails that don’t present much of a traction challenge, your standard pavement air pressure may be just fine.
Situations where you are confronted with more challenging terrain more clearly call for airing down. If you are crossing sand dunes, slogging your way through mud, or crawling up a boulder field, airing down can make a big difference.
It takes me about 30 minutes to air down and air back up again, depending on how much air I let out. I’ll typically air down if I’ll be on a mellow off-road trail for two or more hours. That said, if the run is more technically difficult, I’ll air down every time.
To sum it up, air down if it will improve your comfort over a long ride or help you navigate technical terrain.
And remember that it’s not an all-or-nothing proposition. You can always reduce and increase air pressure on the trail as needed — although it’s better to air down before you need to, as letting out air once you are stuck can present challenges.
What is the best tire pressure for off-roading?
One of the most common questions people ask about airing down tires for off-roading is what pressure is ideal. It’s actually a fairly complex question. The answer depends on several factors: the terrain, your vehicle’s weight, your tires, and your wheels.
Below, I’ll discuss how these various factors affect your decision to air down, but I’m also aware that taking all of these factors into account can be confusing. Like all things off-road, it’s possible to geek out on the details. In the following discussion about terrain, I’ve also tried to simplify airing down to a few simple guidelines that you can use as a baseline.
Here, I’ll tell you what I do. There are MANY opinions on the correct tire pressure for off-roading. I recommend you also talk with other people who off-road and overland in your area and who have a vehicle similar to yours to find out what works for them.
It’s important to remember that nothing is written in stone — experiment to find out what works best for your vehicle, tires, and situation.
A vehicle’s weight impacts how much you can air down its tires. With heavier vehicles, the tire is more likely to come off the rim at low pressures. Thus, you can’t air down the tires as much on a fully loaded overland rig as much as you can a lightly loaded Jeep headed out for a day on the local trails.
Generally speaking, you can air down smaller, stock tires less than you can larger off-road tires. The volume of air in a tire is what keeps the bead locked into the rim (not the PSI).
All things being equal, the pressure in a larger tire can be reduced to a lower PSI with less risk of the tire coming off the rim.
If you have standard wheels, without beadlock rims, there is a greater risk of the tire coming off the rim when you lower the pressure. The lower the pressure, the greater the risk.
Due to the risk of popping a bead, most off-road enthusiasts will keep their tire pressure above the 10-15 PSI range on the trail.
Beadlocks rims with the right tire can be aired down to single-digit PSI numbers, which provides far more traction. The terrain discussion below assumes you don’t have beadlock rims on your vehicle.
Off-Road Terrain and Tire Pressure
Terrain is probably the most important factor in determining how much you air down. Lowering your air pressure can go a long way to helping you successfully navigate tricky terrain.
Here are a few of the specific types of terrain where airing down can really make a difference:
Dirt roads and moderate off-road terrain
If you are traveling on a forest service road or a moderate off-road trail that presents little technical challenge, you might air down just a bit to smooth out the ride.
This is especially true if you’ll be traveling on this trail for a long period of time. In this case, reducing your air pressure serves an important shock absorption role. Your passengers will appreciate that their teeth chatter less.
Usually, taking out 5-10 PSI is plenty for such terrain.
One thing that’s important to keep in mind is that you should drive slowly once you’ve taken a significant amount of air out of your tires. There is a temptation to go fast on easy trails, but tires with low air pressure will make handling sketching at higher speeds and there is a risk of the tire popping off the bead of the wheel.
Lowering the tires by 5-10 psi shouldn’t impact your handling too much and presents a low risk of popping a bead.
Soft ground: Sand, mud, and snow
In soft ground, such as sand, mud, and snow, airing down serves two functions.
First, it increases your tires’ footprint on the ground which increases traction to allow the tires to move the vehicle or stop it. Second, the larger footprint of the tire will help you float on top of the ground instead of sinking into it, which also improves traction, as your tires aren’t fighting to push through the soft ground as much.
If you are traveling on a road that has just a few inches of soft ground to cross, airing down 10 PSI in your tires’ air pressure might work just fine.
If you are traveling through deep sand, snow, or mud, airing down more can make a huge difference. Again, there are no hard and fast rules, but I typically reduce tire pressure to around 12-15 PSI when tackling really soft terrain.
Other people will drop down to 8 to 10 PSI with the same setup, or even lower, reportedly with no incidents of tiers popping a bead, but 12-15 seems to work fine for me.
When you’re driving over a technical, rocky section of trail, reducing your tires’ air pressure improves your crawlin’ capabilities.
Just as with other types of terrain, the larger footprint of an aired-down tire provides more traction as you climb up or down rocks. The lower pressure also allows the tire to conform to the uneven surface of rocks, wrapping around the edges which acts like a rock climber’s hand gripping a rock.
When I’m traveling over a moderately rocky patch, I’ll drop my pressure by 10 psi, which typically get the job done. If I know things are going to gnarlier, I’ll drop down further in advance, typically to around 12 PSI.
How do you air down tires off-road?
Airing down tires while off-roading involves two components: 1) releasing the air, and 2) keeping track of tire pressure.
You can use a simple stick gauge to release the air from your tires, using the nub on the back of the gauge to depress the core of the tire stem, and then checking the pressure as you go. This is the cheap but painfully slow method.
People who off-road and overland regularly will typically use more sophisticated devices to speed up the process. When I first started heading off-road regularly, I used the chuck on my air compressor to air down.
It had a locking release that would hold the valve open without me having to bend down and hold it open. Every so often I’d stop the release and check the tire pressure with the integrated gauge.
This is a good way to get started and saves you some money, as you’ll need to purchase an air compressor anyway if you’re planning to air down.
You can also buy this type of pressure gauge/deflator set up separately from an air compressor.
More recently, I’ve switched to automatic tire deflators, which are preset to the tire pressure I’m targeting.
These come in sets of four, so you can deflate all of your tires simultaneously, which saves a lot of time. Just screw them on and they will release air until they hit the desired pressure.
Another option is deflators that temporarily remove the valve stem from off-road tires to deflate them. These have the advantage of releasing air from the tire quickly. That said, as the air is being released rapidly, you have to monitor each tire closely to make sure you don’t overshoot and lower your pressure too much.
How do you reinflate an off-road tire?
Once you’ve gotten to the end of the trail, you’ll need to inflate your tires. This is where air compressors come in. Air compressors come in on-board and portable versions.
An on-board air compressor is fixed on your vehicle, often in the engine bay, and pre-connected to your battery for power.
Portable compressors usually live in some kind of box or bag that you can carry around, and they must be connected to your battery every time you want to use them.
Another way to fill up your tires is using a tank with compressed CO2, which speeds the process of airing up. This solution is popular among hard-core off-roaders who are on the trails regularly.
For more detailed information, check out our guide to off-road air compressors.