Tyre Pressure Guide for Australian Drivers — What PSI Should My Tyres Be?
Tyre pressure is one of the most commonly neglected aspects of car maintenance in Australia — and one of the cheapest to fix. Incorrect pressure affects fuel economy, tyre life, and most importantly, how your car handles in an emergency. Here's everything you need to know.
How to find the correct pressure for your car
The correct tyre pressure for your specific vehicle is listed on the tyre placard — a sticker usually found inside the driver's door jamb or on the fuel filler cap. The placard specifies pressures for both front and rear tyres, often with different values for each axle, and may include separate figures for normal driving versus fully loaded conditions. Always use the placard figure rather than the maximum pressure stamped on the tyre sidewall — the sidewall figure is the maximum the tyre can physically hold, not the correct operating pressure for your vehicle.
Why tyre pressure matters so much
Underinflated tyres flex excessively, generating heat that accelerates tread wear and can cause tyre failure at high speed — fuel consumption also increases by approximately 0.5% for every 10 kPa drop in pressure. Underinflation increases braking distances and reduces cornering grip in emergency situations. Overinflated tyres reduce the tyre's contact patch, decreasing grip and causing accelerated centre tread wear while transmitting more road impacts through the suspension. A tyre that is 20% underinflated runs at roughly 70°C; a tyre that is 50% underinflated can reach temperatures sufficient to cause tread separation at highway speeds.
When to check tyre pressure
Check pressure monthly and always before a long trip or when carrying heavy loads. Tyres must be cold when checked — driven less than 2 km at low speed — because hot tyres read 4–8 PSI higher than cold, which can lead to incorrect adjustment. Petrol station gauges are often inaccurate due to heavy use and limited calibration; a personal dial gauge costing $15–$25 is worth investing in for accurate and consistent readings. TPMS (tyre pressure monitoring system), fitted to most new Australian cars, alerts you when pressure drops 25% below recommended — useful for emergencies but not a substitute for monthly manual checks.
Front vs rear and loaded vs unloaded
Many vehicles specify different front and rear tyre pressures — the rear is often higher on wagons and SUVs to account for load-carrying requirements. Some vehicles specify significantly higher pressures when fully loaded with passengers and luggage, so check your placard carefully for a separate load pressure. Four-wheel drives used off-road sometimes reduce pressure to 18–22 PSI to improve traction on sand and soft terrain, but must reinflate to highway pressures before returning to sealed roads. Tyre deflators and a portable compressor are standard equipment for serious off-road driving for this reason.
Nitrogen vs air — is it worth it?
Nitrogen-filled tyres maintain pressure more consistently than air because nitrogen molecules are larger and permeate rubber more slowly, and pressure stability over temperature changes is slightly better with nitrogen. However, air is already 78% nitrogen, and the real-world difference between nitrogen and dry compressed air in a well-maintained tyre is minimal for everyday driving. Nitrogen makes practical sense for racing applications and aircraft where precise pressure stability is critical, but for regular Australian motorists the inconvenience and cost of nitrogen top-ups at specialised providers is not justified by the marginal benefit.
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