When do your tyres actually need replacing?
A tyre must be replaced once tread depth reaches the legal minimum of 1.5mm across the tread surface — the point where the wear indicator bars moulded into the grooves sit level with the tread. Tyres also need replacing regardless of tread if they have sidewall cuts or bulges, exposed cord, damage from being run flat, or significant age cracking.
Most people think about tyres in terms of tread depth alone. It is the legal test, but it is not the only reason a tyre is finished.
The legal limit: 1.5mm
The minimum legal tread depth is 1.5mm across the tread surface. You do not need a gauge to check it — every tyre has wear indicator bars moulded into the bottom of the tread grooves, sitting at exactly that height. When the tread wears level with those bars, the tyre is at the limit and will fail a safety certificate inspection.
Reasons to replace regardless of tread
- A cut, bulge or split in the sidewall — this cannot be repaired, and a bulge means the internal structure has already failed
- Exposed cord anywhere on the tyre
- Damage from being driven flat, which happens inside the tyre and is invisible from the outside
- Age cracking — rubber hardens and crazes over time even on a car that barely moves
- A puncture in the shoulder or sidewall, which is not in a repairable area
What uneven wear is telling you
A tyre that is worn unevenly is usually reporting a fault somewhere else on the car, and replacing it without fixing the cause just wears out the new one:
- Both edges worn, middle fine — chronically underinflated
- Middle worn, edges fine — overinflated
- One edge only — an alignment problem
- Scalloped or cupped patches — a balance problem, or worn suspension
That is the advantage of having tyres fitted somewhere with a hoist and a mechanic on site: the wear pattern can be looked into rather than shrugged at.
A Grade Tyre & Auto handles this at the workshop on Lawrence Drive, Nerang.
General information only, current as at 11 September 2026. Requirements change and individual circumstances differ — for anything that turns on your specific situation, check with Queensland Department of Transport and Main Roads on 13 23 80 or at qld.gov.au.