The legal limit for tyre tread depth for a car in the UK is 1.6 millimeters across the central three-quarters of the tyre's tread around its complete circumference. This means the tread must meet or exceed this minimum depth throughout the central 75% of the tyre's width all the way around. Driving with tyres below this limit is illegal and can result in fines up to £2,500 per tyre and penalty points on your driving license. For safety, experts recommend replacing tyres before they reach this legal limit, ideally at around 3 millimeters of tread depth, since stopping distances increase significantly below this point in wet conditions. Regular checks and maintenance ensure tyres stay safe and legal on the road.