A simple 20p coin test on tyre tread before rain could save UK drivers from fines up to £2,500 and three penalty points per illegal tyre, according to safety experts.
Sudden downpours after dry spells make roads slicker, and tyres with worn tread are more likely to lose grip when braking, cornering or steering. The test takes less than a minute and involves pushing a 20p coin into the main grooves of the tread at several points, as tyres do not wear evenly.
If the tread does not cover the coin's outer rim, the tyre may be running too close to the legal minimum of 1.6mm across the central three-quarters of the tyre and around the full circumference. In that case, drivers should have it properly measured rather than risk wet roads.
Expert warns of hidden dangers
Ollie Green, car safety expert at Collect Service Go, said: "Most people don't think about their tyres until something feels wrong, but that's exactly why quick checks are useful. Summer can give you long stretches of dry weather followed by a really heavy downpour, and that change in conditions can catch drivers out."
He added: "If your tyres are already worn, you don't want the first time you find out to be when you're trying to brake or steer on a wet road." He also urged motorists to look for cracks, bulges and uneven wear.
Costs and penalties
Checkatrade says replacement tyres typically cost £45 to £250 each, including fitting and balancing, with many motorists paying £70 to £120 for a mid-range option. Prices vary by brand, tyre size and fitting choice.
Drivers with illegal tyres can be fined up to £2,500 and get three penalty points per tyre, meaning four illegal tyres could lead to £10,000 in fines and 12 points, effectively a ban.
The 20p test is not a replacement for proper tread depth measurement, so concerned drivers should get tyres checked. Experts also advise checking tyre pressures, especially before long motorway runs, as under-inflated tyres can worsen braking and handling and wear edges faster.
