There's no single answer to how long a tyre lasts, because there are two clocks running at once. One is the tread, which wears down with every kilometre. The other is the rubber itself, which hardens and cracks with age whether the car is driven or not. A tyre is finished when either clock runs out.

The tread clock

How fast tread wears depends far more on the car and the driver than on the tyre alone. These are the things that shorten it most:

  • Wheel alignment that's out — the single biggest cause of tyres wearing out early, and often on one edge where you won't notice.
  • Running pressures too low or too high.
  • Hard acceleration, braking and cornering.
  • Heavy loads and towing.
  • Lots of short trips and tight turns in town.

The age clock

Rubber ages from the day it's made. Sun, heat and long periods of standing still speed it up, which is why tyres on low-kilometre cars, caravans, trailers and spares often age out long before they wear out. The signs are fine cracking in the sidewall and between the tread blocks, and rubber that feels hard rather than supple.

New Zealand has no fixed age limit for car tyres, and a WOF inspector isn't checking the date. They are checking condition, though, and a perished, cracked tyre can fail on that. Tyre makers' general advice is to have tyres inspected every year once they're five years old, and to replace them by ten years old regardless of how much tread is left. Some vehicle manufacturers set a shorter limit, so check your owner's manual.

How to read the date

Look on the sidewall for a code beginning "DOT". The last four digits are the week and year of manufacture: 2219 means week 22 of 2019. It may only be on one side of the tyre, so if you can't find it, check the inside face.

Getting the most out of a set

  • Check pressures monthly, when the tyres are cold.
  • Have the alignment checked every 10,000km or once a year, and whenever new tyres go on.
  • Get a slow leak looked at early.
  • Look over your spare and any trailer tyres now and then — they're the ones that get forgotten.

Not sure how much life your tyres have left? Bring the car to 151 Totara Street, Mount Maunganui, and we'll check the tread, the date and the condition, and tell you straight. Call +64 29 777 7122.