All drivers are (or should be!) aware that the legal minimum tread depth is 1.6mm, but do you know why tread is so important?

Your tyres are your only contact with the road, and that contact is much smaller than you might think. The surface of each car tyre that is actually in contact with the road is about the size of a handprint. That’s all you have to grip the road with, and as around half of all car accidents are caused by the car skidding when the tyres cannot keep hold of the road, it is vitally important that there are no areas of your tyres that have less than 1.6mm tread.

The tread is what lets the tyre grip the road when it is wet. The grooves channel out the excess water, and if the tread is not deep enough, it will not be able to disperse the water quickly enough at higher speeds. The car will then aquaplane as there is a sheet of water between the tyre and the road, and that small, handprint sized contact point is gone.

The area you need to check is the central three quarters of the width of the tyre, all the way around the circumference. You should check it with a tread depth gauge in several places across this width and around the circumference. You may find that your tyres wear unevenly, particularly if you have to drive around many roundabouts, but as soon as any part of your tyre is getting close to 1.6mm, you should have a new car tyre fitted.