Check tyre tread with a 20p coin

You’re running late, hopping into your car, and—uh-oh—that front tyre looks suspiciously bald. Is it still legal? Maybe you’re eyeing a bargain used tyre online but don’t trust the seller’s word. Whatever the case, you need to know: Will this pass an MOT, or am I risking a fine?

Good news — you don’t need fancy tools to figure it out. Here’s how to check a used tyre’s legality with stuff you’ve already got lying around.

The 20p test: Your pocket-sized tyre inspector

No tread depth gauge? No problem. Grab a 20p coin and follow this:

• Insert the coin into the tyre’s main tread grooves;
• Check the outer band – If the coin’s outer rim is hidden, your tread is above the legal limit (1.6mm in the UK).

If you see the rim, the tyre’s borderline illegal and needs replacing.

Pro tip: Test multiple spots across the tyre. Uneven wear? That could mean alignment issues—worth fixing before your next set of tyres wears out the same way.

The “No-Go” Zones: Cracks, Bulges & Other Red Flags

Tread depth isn’t the only dealbreaker. Run your hands over the tyre (watch for sharp objects!) and look for:

• Cracks in the sidewall – Sun damage or ageing rubber can weaken the structure.
• Bulges or blisters – A sign of internal damage; could blow out at speed.
• Patch repairs – If there’s more than one, or they’re within 25cm of each other, the tyre’s likely unsafe.

Fun fact: A tyre can look fine but still be illegal. If it’s over 10 years old (check the DOT code on the sidewall), many garages won’t fit it, even with decent tread.