When and Why to Deflate Your Tires

Have you ever wondered why so many people air down their tires before heading off-road?

Lowering your tire pressure allows the tire to become softer and more flexible. This can improve ride quality, help the tire conform to uneven terrain, and increase the amount of tread contacting the ground. All of that can improve traction.

And when we say “off-road,” that can mean a lot of different things. It might be a washboard dirt road where you’re traveling under 30 mph, a soft sand wash where you need more flotation and traction, or a rocky Colorado trail where you’re crawling over ledges and obstacles.

So, you’ve reached the beginning of the trail. What pressure should you air down to?

There isn’t one perfect answer. Several factors determine how low you should go:

• What size are your tires?
• How heavy is your vehicle?
• What type of terrain will you be traveling over?
• What brand and construction are your tires?
• How stiff is the tire and what load range is it?
• Do you have beadlock wheels?

Tire size and vehicle weight

Generally, the larger the tire, the lower the pressure you may be able to run off-road. But tire size has to be considered along with the weight of the vehicle.

A lightweight Jeep on 37-inch tires may behave very differently at the same pressure as a heavier truck on similar-sized tires.

Terrain matters

The type of terrain is another important consideration.

On softer surfaces such as sand, lowering your tire pressure can help increase the tire’s footprint and allow the vehicle to float over the surface instead of digging into it.

On rocky or hard terrain, airing down can still greatly improve traction and ride quality, but you also need to be more careful. Extremely low pressure combined with side loads or impacts can increase the chance of pushing the tire bead away from the wheel.

Tire construction

Not all tires react the same way when aired down.

Some tires have very stiff sidewalls because of their construction, while others are much more flexible. A heavier-duty tire may need to be aired down farther before you notice much change in ride quality or tire flex.

That is why knowing your tires, and learning how they behave on your particular vehicle, is so important.

Load range and sidewall stiffness

A lighter-duty tire will generally flex more easily than a heavy-duty tire.

For example, a tire with a softer carcass may not need to be aired down as much to get the desired ride and traction. A heavier-duty tire with a stiff sidewall may need considerably less pressure before it begins to conform to the terrain.

Instead of focusing only on the number of plies, pay attention to the tire’s load range, construction, and how stiff the sidewall actually feels on your vehicle.

Beadlock wheels

One of the biggest factors in determining how low you can safely go is whether you have beadlock wheels.

A true beadlock wheel mechanically clamps the outer tire bead to the wheel. This greatly reduces the likelihood of the tire bead separating from the wheel when running very low pressures off-road. Without beadlocks, you need to be more conservative.

Several of our recent shop builds run beadlock wheels for exactly this reason. You can see a few of them on our custom builds page.

As a general starting point, many off-road vehicles without beadlocks may run somewhere around 10 to 14 PSI. With beadlock wheels, 8 to 10 PSI can often work very well, and some properly equipped vehicles may run even lower.

These numbers are only starting points, not universal recommendations. Every tire, wheel, vehicle, and trail combination is different.

Don’t air down unless you can air back up

This is one of the most important things to remember.

Don’t air down your tires unless you have a reliable way to air them back up.

Before returning to pavement and highway speeds, you need to bring your tires back to an appropriate street pressure. Carrying a quality onboard air compressor, portable compressor, or CO2 system gives you the ability to air back up after a day on the trail.

And if a rock cut or a nail catches you out there before you get the chance to air back up, it helps to know how to patch it on the spot. We covered that in how to fix a tire puncture on the trail.

Airing down can make a tremendous difference in ride quality, traction, and overall control off-road. Like most things in four-wheeling, knowing your equipment and using it correctly is what makes the difference.

In the next Scott’s Korner, we’ll talk about the different ways to air down efficiently and air back up when the trail is over.

Trail-tested knowledge for every off-road adventure. Until next time, let’s enjoy the trail!