06 February, 2019

Tyre Tread Q&A

Here at CompareNewTyres.com HQ we get asked questions about tyres all the time, the most common being about tread depth. The questions we get asked normally start with “My friend Dave….” Or “Suzy from over the road said….”.


As the questions are really common, we thought it would be more helpful if we have a short Q&A session on our blog, so here are the questions we get asked and their answers.


Q. My mechanic says my tyres are '50% worn', what does this mean?
A. Historically a mechanic would check your tyres and tell you that you have XX thousand miles to go before they need changing, but unfortunately this estimate of mileage doesn't account for each individual style of driving, so where you may get 5,000 miles out of 4mm of tread, I might only get 2,000 miles because I drive differently. So many mechanics changed and went to a percentage worn, which simply shows you how much tread you have left and gives an indication of whether you might need to change a tyre soon.

Below is a short graphic detailing how much tread you have left on your tyres by percentage worn. By the time you get in to the orange and certainly in the red, it's time to consider changing your tyres. 

Q. I have been told that I need to change my tyres when the tread reaches 3mm, is that right?

A. For cars the legal tread depth is 1.6mm, so anything above this is a legal tread depth. That said, most tyre manufacturers advise that you should replace your tyres at around 3mm as when their tread is below 3mm they don’t perform as well. The only exception to this is Michelin who say you can use their tyres right down to 1.6mm without any noticeable loss of performance.


Q. Do I need to have tread across the whole tyre?
A. Bizarrely no you don’t. UK law says that you only need to have the 1.6mm tread (for cars) in a continuous band in the centre three quarters of the tread and around the entire circumference. Essentially, the shoulders or outer edges of your tyre can be bald but perfectly legal.


Q. How do I work out where the centre three quarters are?
A. We have created a short diagram to show you. If you imagine a tyre with a width of 200mm, then the central three quarters would be 75mm either side of the centre of the tyre. In our image below, we show you the centre line, the area required to have tread (shown by a shaded area) and the dimensions of the tyre.




Q. Is it safe to drive with only the central three quarters having tread?
A. You have to remember the law is setting a minimum level of what is acceptable and safe. In the same way that tyres with over 3mm of tread perform better, tyres with tread on the shoulders / outer edges will always perform better than those without, so our advice is always to change your tyres if you shoulders / outer edges are worn.


Q. Why does the tread on the outer edge worn quicker than the tyre?
A. Generally when the outer edges or shoulders of the tyre wear quicker than the tread, it indicates that your tyres need inflating and have been running whilst underinflated for some time. Make sure you check your tyre pressures against the manufacturers recommended pressures.

If you have any questions about tyres, then why not use the Contact Us section and send us your questions.