Tyre Pressure: Why It Matters and How to Check It

Why tyre pressure matters

Your tyres are the only contact between your car and the road. Correct pressure affects three critical areas:

1. Safety — underinflated tyres overheat and are more prone to blowouts. Overinflated tyres have less grip, especially in wet conditions. Both increase stopping distance.
2. Fuel economy — underinflation increases rolling resistance. A tyre 20% below its recommended pressure can reduce fuel economy by several percent.
3. Tyre life — incorrect pressure causes uneven wear. Underinflated tyres wear at the edges; overinflated tyres wear in the centre. Both shorten the usable life of the tyre.

Finding the correct pressure

The recommended pressure for your car is not printed on the tyre itself — that number is the maximum pressure the tyre can hold. The correct pressure for your vehicle is found in:

• The tyre pressure placard — usually on the driver's door jamb, inside the fuel filler door, or in the glove box.
• Your owner's manual.
• Sometimes the placard lists different pressures for front and rear tyres, and a higher pressure for full loads.

Typical pressures range from 30 to 36 psi (2.0 to 2.5 bar) for passenger cars, but always use the specific figure for your vehicle.

When to check

• At least once a month.
• Before long trips or when carrying heavy loads.
• When the seasons change — pressure drops in cold weather and rises in hot weather.
• After hitting a pothole or kerb — check for pressure loss or damage.

Tyres naturally lose a small amount of pressure over time, so do not wait for a tyre to look flat — by the time it is visible, it is already dangerously low.

How to check tyre pressure

1. Check when tyres are cold. Tyres heat up while driving, which increases the pressure reading. Ideally, check before driving or after less than 3 km of driving. If you have been driving, add roughly 3–4 psi to the recommended figure as an approximation.
2. Remove the valve cap from the tyre.
3. Press a pressure gauge firmly onto the valve. You should hear a brief hiss, then the gauge shows the reading.
4. Compare to the recommended pressure. If it is low, add air. If it is high, release a small amount and recheck.
5. Replace the valve cap — it keeps dirt and moisture out of the valve.
6. Check all four tyres, plus the spare if your car has one.

A simple handheld pressure gauge is inexpensive and worth keeping in the car. Many fuel stations have air pumps with built-in gauges, though these can be less accurate.

Signs of incorrect pressure

Underinflation

• Both edges of the tread wear faster than the centre.
• The car may feel sluggish or heavy to steer.
• Fuel economy drops.
• The tyre heats up more during driving.

Overinflation

• The centre of the tread wears faster than the edges.
• The ride feels harsh or bumpy.
• Grip is reduced, especially on wet roads.

Tyre pressure monitoring systems (TPMS)

Many modern cars have a TPMS that warns you when a tyre is significantly underinflated. If you see a tyre pressure warning light, check your pressures as soon as possible. Note that TPMS typically only warns at a significant pressure drop — it does not replace regular manual checks.

See our guide to Understanding Common Dashboard Warning Lights for more on TPMS and other warning indicators.

Related guides

• Basic Car Maintenance Checklist
• What Affects Fuel Economy?