4×4 Driving Tips: Choosing the right tyre pressures.

Tyre pressures are your greatest ally for improving off-road capability and comfort. You’ll go further off-road and do it a lot easier. And that means you’ll be more relaxed behind the wheel, and there is less strain on your vehicle and the environment. My early years of off-roading were spent in underpowered vehicles, old Land Rovers mostly. I didn’t have bulk power, locking differentials, or traction control to help take on the track’s tricky sections. I could only play the cards I had, playing with tire pressures and being crafty with the line I chose.
It was an excellent way to learn: the lower your pressures go, the more capable your vehicle becomes. My old, worn-out Sime tires managed to grip and hold traction on some pretty challenging parts of the track instead of spinning and bouncing.

The basics are pretty simple: the lower your tire pressures are, the larger the contact patch each tire makes with the ground. Lower pressure lets the casing become much more pliable as it molds to the terrain, and you’re left with significantly more mechanical grip. It doesn’t matter whether you’re driving on mud, rocks, sand, dirt, snow, or through water; lowering your tire pressures to a certain degree is always a good idea. Generally speaking, the harder the challenge and the slower you are driving, the lower your pressures can go… to a point. Rolling a tire off the bead on Stockton Beach gave me my starting point for too low.

So, what’s the best pressure for you? Recommending specific tire pressures for an each-and-every person out there is difficult because of all the variables. Vehicle size, weight, wheel/tire combination, and driving style all play a part in what kind of pressures are safe to run off-road. The best advice you can get in terms of finding your sweet spot is experimentation and practice. With a decent quality air compressor and accurate gauge at the ready, take some time to try out a few different pressures to see what feels the best from the driver’s seat. If you’re slipping around the place or getting bogged, that’s probably your vehicle telling you pressures are too high. And you’ll notice when you do get it right, your 4WD will feel much more capable and comfortable.

So, we can all agree that lowering tire pressures are king off-road. There are some risks to be aware of, however. And it’s also entirely possible to go too low and do some serious damage. There are two big issues to be aware of: heat build-up and rolling a tire off the bead. Both scenarios are easily managed, as long as you’re aware of them when driving and setting your pressures.

The Heat

Heat build-up happens when you’re driving at too high a high speed with low tire pressures. Other than your handling and braking being seriously compromised, the sidewalls will be continually flexing in and out where the tire bulges at the bottom. Flexing makes friction, and friction makes heat. That’s the perfect recipe for heat build-up if left unchecked, contributing to irreversible damage to the tire’s construction. Keep going, and you’ll likely get full-blown delamination. To avoid this, be prepared and able to air up as well as air down. And don’t go too fast while your tire pressures are low.

If you’re unsure, it’s probably worth spending the time to air up a bit. If you hop out of the car and the sidewalls of your tires are hot to touch, that’s a surefire indicator you’ve got too little air, you’re driving too fast, or both. Your tires are getting hot, and doing this for long periods will do damage.

The Bead

The other issue, rolling a tire off the bead, is handled by your driving style. While big steering and throttle inputs aren’t going to impact anything on-road with normal pressures, there is a big difference when you let out some wind. While the much-celebrated sand-flying, rooster-tailing photograph of a sharp turn at speed on the beach is hard to escape (especially in the media), it’s a patently bad idea. Tires are joined to the wheel at the bead, forced together by the air trapped inside. Less air pressure inside means there is less force keeping the wheel and tire together. Low pressures and steering sharply will prise the tire and wheel apart, so don’t do it.

Don’t bury the go and stop pedals if you can help it either. Tires have been known to spin on the wheel at low pressures. It’s not a show stopper, but it will annoyingly put your wheels out of balance. That means your car will now drive like crap, and you’ll have to spend your time and money at a shop getting it fixed. If you change your driving habits enough, which means going easy on the big throttle, braking, and steering inputs, you’ll almost eliminate the risk of rolling a bead. It’s still possible but improbable when you take it easy. Steer slowly and progressively, and apply your throttle and brakes even more so. You’re not in a hurry anyway.

So how low do I go?

Lower is better. It’s hard to recommend a blanket pressure for people to aim for because of all of the variables surrounding vehicles and drivers. However, a rough guide might help to get you started. There is a big caveat with this guide, however. Find out what works with your vehicle and application, keeping in mind every wheel/tire combination, vehicle weight, and wheelbase can all makes a difference. Going towards the lower end of the scale will reap more benefandalso increase the risk of heat build-up and popping a bead.

The CarAdvice rough guide to off-road tire pressures

High-speed, smooth dirt: 28+ psi Easy conditions: Unsealed, rocky and rough roads: 22-28 psi Medium conditions: firm sand, low-speed dirt, mild ruts, and washouts: 18-24 psi Hard conditions: Rock crawling, soft sand, thick mud, big ruts, washouts, and rock steps: 14-20 psi As I said, the guide should only be considered as a starting point. Everyone has their setup and driving style, along with their preferences for pressures. And of course, don’t leave home without a decent air compressor and quality gauge/deflator, which will let you adjust and experiment with your pressures. And finally, don’t forget the recovery gear and shovel, as well, just in case.