For most 4WDs, a sensible starting point is around 15 to 20 psi for sand, the high 20s to low 30s for rough gravel and corrugations, and the low-to-mid 20s for slow rock work, then straight back to your placard pressure before you return to the bitumen. Those numbers are only a launch pad: your vehicle's weight, the tyre's construction and the surface on the day decide where you finish.
This guide walks through why airing down works, how far to go on each surface, how to do it without damaging a tyre, and how to get back to road pressure safely.
Why letting air out makes such a difference
A tyre at highway pressure is firm and round, so only a small patch of tread touches the ground. Drop the pressure and the tyre relaxes, the sidewalls bulge slightly and the footprint grows longer. On soft sand that bigger footprint spreads the vehicle's weight, so the tyre floats over the surface instead of digging a hole.
On gravel and rock, the softer tyre wraps around stones rather than bouncing off them. You get more grip, a smoother ride, less shaking through the cabin and a lower chance of a sharp rock piercing a rock-hard tread.
The trade-off is heat and stability. A softer tyre flexes more with every turn of the wheel, and flexing builds heat. That is why every drop in pressure needs a matching drop in speed.
Starting pressures by surface
Begin with the cold pressure on your vehicle's tyre placard, usually found on the driver's door pillar, and work down from there. The table gives common starting points for a typical wagon or dual-cab ute on standard rims.
| Surface | Typical starting point | What to watch |
|---|---|---|
| Sealed road | Your placard pressure (higher when loaded) | Check cold, before you set off |
| Smooth gravel | A few psi below road pressure | Ease off the speed a little |
| Rough gravel and corrugations | Roughly 26 to 32 psi | Heat on long, fast sections |
| Rock and low-range tracks | Low-to-mid 20s psi | Sidewall cuts, sharp edges, sudden steering |
| Firm or general sand | Roughly 15 to 20 psi | Keep momentum, avoid sharp turns |
| Very soft sand | Mid-teens psi | Bead security, very low speed |
Treat about 15 psi as a practical floor on standard rims. Below that, a sharp turn or a burst of throttle can push the tyre off its bead, and you go from bogged to flat in a second. Always check your vehicle maker's recommended minimum as well.
Three things move the right number up or down.
Load and towing
A heavy vehicle squashes its tyres more at any given pressure. A fully loaded touring rig with water, a fridge, drawers and a roof tent may need a few psi more than the same vehicle running empty, especially at the rear. Towing a camper adds weight to the rear axle again. Never run so low that the tyre is working beyond the load rating printed on its sidewall.
Tyre construction
Light truck (LT) tyres have stiffer sidewalls and more plies than passenger-construction 4x4 tyres. They cope better with low pressures on rock and corrugations and resist bruising and punctures. Stiff rugged-terrain and mud-terrain tyres may need a little less air than a softer all-terrain to get the same footprint, so judge the bulge, not just the gauge.
Temperature
Pressure rises as a tyre warms up. A reading taken after an hour on a hot desert track will be higher than the same tyre first thing in the morning. Set your pressures cold where you can, and avoid letting air out of hot tyres to chase a number, or they will be too soft once they cool.
How to air down safely
- Stop somewhere safe and level, off the track and out of the way of other vehicles. Pick shade on a hot day.
- Note your starting pressures. A quality digital or low-pressure gauge is far more accurate than a cheap stick gauge at these numbers.
- Use deflators or a valve-core tool. Screw-on deflators that stop at a preset pressure let you do all four tyres at once and keep them even.
- Go in steps. On a new surface, drop to your starting point first. If you are still struggling, take a few more psi out rather than jumping straight to the bottom of the range.
- Check that all four tyres match. Uneven pressures side to side make the vehicle pull and wander.
- Refit the valve caps. Sand and grit in a valve is a slow leak waiting to happen.
Driving on low pressures
Once aired down, drive as if the tyres are fragile, because they are. Keep the speed down, make smooth steering inputs and avoid hard braking or sudden bursts of throttle. Sharp turns on soft sand are the classic way to peel a tyre off its rim.
On sand, momentum is your friend. A steady, sensible speed keeps the vehicle floating, while stopping on a slope or in deep, churned sand makes it harder to get going again. If you start to bog, stop before the wheels dig in. Let a little more air out, reverse gently back along your own tracks, then drive forward again.
On rock, walk the line first, use low range and let each tyre roll over edges slowly. Watch for sharp stones near the sidewall, which bulges more at low pressure and is the part of the tyre most likely to be cut.
Carry recovery gear whenever you leave the bitumen: a shovel, traction boards, a rated snatch strap with suitable shackles, a solid jack base and a good spare.
Airing back up for the highway
Low pressures on bitumen at highway speed are a real hazard. The tyre overheats, the steering goes soft and vague, and the vehicle is less stable under braking. Re-inflate as soon as you are back on a hard surface, and keep the speed down until you do.
- Carry a reliable 12V compressor. A unit with a decent duty cycle and a long hose will fill four large tyres without overheating.
- Inflate to your placard pressure, adjusted for load and towing, and remember a warm tyre reads a little high.
- Inspect while you inflate. Look for cuts, bulges, stones lodged in the tread and damage to the valve stems.
- Only a short stretch of bitumen? If more dirt follows soon, you can stay aired down for a brief run, but drive slowly.
Make a final check the next morning when the tyres are cold, and top up any that have dropped. A slow loss after a trip can point to a small puncture or a bead that has picked up sand.
Choosing tyres that handle pressure changes
If you air down often, construction matters as much as tread pattern, and LT tyres with tough sidewalls handle repeated low pressures best. In 265/65R17, a popular size on many utes and wagons, options include the Lanvigator Land Warrior R/T, the Ninevont Fighter PT-Z20 and the Sabin Pearlman Baja Good AT, all in LT construction. For a touring setup that spends more time on gravel and highway, the Keter HyperTrax all-terrain is worth a look.
See every pattern in that size with our 265/65R17 search, compare all-terrain tyres, or read the tyre guide for help choosing. When it is time to fit them, book a local workshop or mobile fitter near you.
Common questions
What tyre pressure should I run on the beach?
Most 4WDs start around 15 to 20 psi on beach sand, heading toward the mid-teens in very soft, dry sand. Heavier vehicles and fine sand usually need the lower end. Check your vehicle maker's minimum first.
Can I drive on the highway with aired-down tyres?
Only for a short distance at low speed. At highway speeds, low pressures overheat the tyre and make the vehicle unstable. Re-inflate to your placard pressure as soon as you reach the bitumen.
How low is too low?
On standard rims, about 15 psi is a practical floor. Lower than that and the tyre can come off the rim in a sharp turn. Beadlock rims allow lower pressures, but check the rules for road use in your state or territory first.
Do LT tyres need different pressures?
LT tyres are stiffer, so they may need slightly less air than a passenger-construction tyre to reach the same footprint. Use the starting points above, then judge by how the tyre bulges and how the vehicle drives.