Tyre tread depth – when should I replace my tyres?
Even with a tread depth of 4 mm, road holding distinctly deteriorates, especially in wet conditions. The tyres can lose contact with the road, thus leading to steering and braking difficulties. Therefore don’t wait until the tread depth has reached the legal limit of 1.6 mm before replacing your tyres. Summer tyres should be changed when the tread depth reaches 2 to 2.5 mm and winter tyres at 4 mm. Tread depth can best be measured at the lowest point in the principal grooves. In measuring the degree of wear in the tread depth, any bridge-like protrusions or reinforcements in the tread base can be ignored. You will often find the abbreviation “TWI” (sometimes other letters are used) or tread wear indicator branded into the tyre sidewall. If you follow the arrow you’ll find a small rubber moulding 1.6 mm above the base of the tread groove. When the tread beside this point has worn down to this level, you can see that the tyre has reached the wear limit and should be replaced. Remember: in the UK by law, cars must have a tread depth of at least 1.6 mm across the central three-quarters of the breadth of the tread and around the entire circumference of the tyre. However, don’t let it reach this level. It has already been shown that even below 3 mm, especially in the wet, road adhesion is seriously reduced!
