Tire pressure: the number that quietly runs your car

Tires are the only part of your car that touches the road, and air is what gives them their shape under load. Get the pressure right and everything downstream improves: braking, cornering, comfort, wear, even fuel use. Get it wrong and the tire fails at all of them — quietly, for thousands of kilometres, until it wears out early or lets go at the worst moment.

Why it matters more than you think

Pressure decides how the tread sits on the road. Too low and the tire flexes on its shoulders, running hot, scrubbing the edges and dragging your economy down. Too high and it balloons onto its centerline, shrinking the contact patch and turning every bump into a jolt.

• Under-inflation wears both shoulders and can overheat at speed.
• Over-inflation wears the center and reduces grip and comfort.
• Correct pressure spreads the load evenly across the full tread.
• Even 0.3 bar low measurably raises rolling resistance and fuel use.

Finding your correct pressure

Your number is not printed on the tire — the figure on the sidewall is a maximum, not a recommendation. The correct pressure for your car is set by the manufacturer.

1. Open the driver's door

   Look for the placard on the door jamb or the inside of the fuel flap. It lists front and rear pressures, often with a loaded option.

2. Check cold

   Measure before driving, or after the car has rested at least three hours. Driving heats the air and adds false pressure.

3. Set every tire, including the spare

   Use a single trusted gauge and match the placard exactly. Refit the valve caps — they keep dirt and moisture out of the valve.

How often to check

Tires lose roughly 0.07 bar (1 PSI) a month just by permeation, and more when the seasons turn — air contracts in the cold, so a tire set in autumn can be noticeably low by deep winter. A monthly check, plus one before any long trip, keeps you in the safe band.