The legal minimum tread depth for car tyres in the uk is 1.6 millimeters, across the central ¾ which is 75% of the tread around the complete circumference of the tyre.
A tyre tread check starts with a thorough visual inspection. Start by turning the steering wheel so you can see across the entire surface of the tread. You are looking for any signs of irregular wear that could be effecting one area of the tread more than another. If the tyres are wearing evenly, you should then determine if you have enough tread on your tyre.
A quick visual check of your tread depth can be made by simply looking at the wear indicators which you’ll find in the grooves of the tread pattern. However, a more accurate and reliable way is to use a depth measuring gauge. It’s small enough to keep in the glovebox and will give an accurate measure of the tread depth of your tyres.
Use a tread depth gauge — a tool to give you a fast, easy-to-read measurement.
Use Tread Wear Indicator (TWI)
Tread-wear indicators (TWI) means the projections within the tread grooves designed to give a visual indication of the degree of wear of the tread.
Premium tyre manufacturers mould TWI's into the design of the tyres' tread pattern. It's easily identifiable; it's made up of six or more small rubs across the bottom of the main tread grooves, which are usually 1.6mm to 2mm above the base of the groove. The legal limit of 1.6mm is reached when the tyre is worn to the level of the tread wear indicators in the main groove — as soon as this happens, the tyre should be replaced.
Remember: - Check your tread depth on all four tyres - Check the inner, centre and outer.
Another easy way to measure the depth of the tread. You can use the quick and simple 20p test. Insert a 20p coin into the lowest tread depth of your tyres. If you can’t see the outer rim around the edge of the coin, then your tyre is safe and has a minimum of 3mm tread depth. If you CAN see the rim then your tyre tread is less than 3mm and should be checked by a professional.
In an ideal world, you should check your tyre’s tread depth and pressure at least once every two weeks, and at the very least once a month. Safe and correct tyre treads are vital especially when travelling on long journeys and on motorways.
More tread means more grip. It's as simple as that. Be aware that even though the legal limit is 1.6mm, anything under 3mm can seriously compromise performance and safety.
In wet weather tyre tread grooves help to remove water from the contact patch between your tyres and the road surface meaning your car can brake, steer and accelerate properly.
Without adequate tread depth, your tyres may not be able to perform properly in wet conditions, reducing your safety on the road. It is therefore advisable to consider replacing your tyres well before they reach the legal minimum.
For safety reasons, it is recommended that you replace your tyres before the legal limit is reached. Many vehicle manufacturers recommend replacing at 3 millimeters. It’s always better to be safe than sorry!
Furthermore, drivers whose tyres fail to comply with the minimum tread depth requirements risk a fine of up to £2,500 and three penalty points for each illegal tyre