Driving on an illegal tyre carries a penalty of up to £2,500 and 3 penalty points — per tyre. That means four bad tyres could in theory cost £10,000 and 12 points, an automatic ban. It can also leave your insurance invalid if you're involved in a collision.
What makes a tyre illegal?
- Tread below the legal 1.6mm minimum anywhere in the central three-quarters.
- Cuts longer than 25mm or 10% of the section width, whichever is greater.
- Lumps, bulges or cord visible through the rubber.
- An under-inflated or over-inflated tyre that's clearly unfit for use.
- The wrong size, construction or speed/load rating for the vehicle.
Why the penalties are "per tyre"
The law treats each defective tyre as a separate offence, which is why costs add up so fast. Police can issue penalties at the roadside, and defective tyres are a routine finding at vehicle checks. Beyond the fine, the bigger risk is safety: worn tyres dramatically increase stopping distances in the wet.
Insurance implications
If you have an accident on tyres that were illegal, your insurer may reduce or refuse a payout, arguing the vehicle wasn't roadworthy. That financial exposure usually dwarfs the cost of new tyres.
Stay legal without the hassle
Check your tyres monthly with the 20p test and replace anything marginal. If you'd rather not drive to a garage on a doubtful tyre, our 24-hour mobile fitters come to you across London and Birmingham, day or night. Book here.
