You set your tyre pressure at the servo, on bitumen, in the morning. Then you turn off onto a corrugated dirt road for 200km.
That's the wrong pressure for the surface you're on.
Why Pressure Matters on Dirt
On corrugated or rough dirt roads, running your tyres at bitumen pressure (typically 35–40 PSI for a 4WD) means the tyre is too stiff to conform to the surface properly. The vehicle bounces more, handling is reduced, and tyre wear — particularly sidewall fatigue — accelerates significantly.
Dropping tyre pressure to 28–32 PSI for dirt road running (depending on your vehicle and load) lets the tyre flex more, absorb corrugations better, and run cooler. It also gives you a larger contact patch, which improves traction.
The Heat Factor
Central Australian temperatures mean your tyres are already running warmer than normal. Heat increases tyre pressure (roughly 1 PSI for every 10°C rise in temperature). A tyre that started at 36 PSI cold can be at 40+ PSI after an hour on hot bitumen in summer.
Overinflated tyres wear faster in the centre of the tread and are more susceptible to impact damage.
After Dirt: Re-Inflate Before Bitumen
If you've deflated for dirt road driving, re-inflate to bitumen pressures before returning to the highway. Underinflated tyres on bitumen at highway speed generate heat and flex in the sidewall — the combination that causes tyre failure.
Tyre Inspection
After any significant dirt road trip, inspect your tyres for sidewall cuts and bruising. A sidewall injury isn't always obvious immediately — it can fail days later.
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