Tyre Pressures, Tread Bands, And Wear Patterns

Cold Numbers

Some cars print the figures on the driver\'s end of the facia. They apply to the original-equipment tyre. Another make may want a different number from its maker. Above 160 km/h (100 mph) the handbook may ask for more pressure. The space-saver is not a high-speed wheel.

• Comfort: 2.1 bar (30 psi) front and rear.
• Normal: 2.6 bar (38 psi) front, 2.4 bar (35 psi) rear.
• Space-saver: 4.1 bar (60 psi).

Measure cold. A hot tyre reads high and you will set it wrong. If you pumped them for a loaded run, drop them back afterwards.

Tread

The original tyres have wear bars that appear at about 1.6 mm. A triangle on the sidewall marks the bar. A cheap depth gauge is more honest than a glance. Pull nails and stones before they reach the cord. A nail that has made a hole goes back in as a marker, then the wheel comes off.

What The Pattern Is Saying

• Both shoulders: under-inflation, heat, a tyre that can let go.
• Centre bald: over-inflation, a harsh ride, shock into the carcass.
• One shoulder: camber. Look at the suspension.
• Feathered edge: toe. You feel it more than you see it. Tracking is a tyre-shop job.
• Shake at about 80 km/h: balance. Through the wheel only, fronts. Through the whole car, rears as well.

Alloy rims mark easily on kerbs. A bent steel rim is often scrap. Fronts wear faster than rears; rotating them evens that out, and then you buy four at once.