What's the legal tyre tread depth for an HGV?

The number most people remember is for a car. Heavy goods vehicles are held to a different one — and it catches drivers out at the roadside.

Where the tread actually has to be

The 1mm isn't measured on one lucky spot. The law asks for a continuous band of at least 1mm of tread across the middle three-quarters of the tyre's breadth, and around its entire circumference. The original tread pattern must still be visible across the rest of the tyre too.

In plain terms: one bald patch, or a worn shoulder that dips under 1mm around the wheel, fails the whole tyre — even if the centre still looks legal. That's why a proper walkaround means running your eye (and a depth gauge) right across and right round each tyre, not just glancing at it.

Tread isn't the only thing that fails a tyre

Plenty of tyres are pulled at the roadside with legal tread. These are instant prohibitions regardless of how much tread is left:

What it costs if you drive on it

Tyre offences on a goods vehicle are dealt with at court, not by a fixed penalty. Each illegal tyre can carry a fine of up to £2,500 and 3 penalty points — and that's per tyre. An examiner will normally also issue an immediate prohibition, so the vehicle isn't going anywhere until it's put right. Four illegal tyres is a very expensive, very bad day.

The practical rule

Don't run a tyre down to the limit. 1mm is where it becomes illegal, not where it becomes worth changing. Uneven wear means part of a tyre can be under 1mm while the rest looks fine, so plan replacement with a margin — and record the check either way, because the paper trail is what protects you at audit.