Your tyres are the only part of the car that touches the road, so they do a lot of work for their size: steering, braking and grip in the wet all depend on them. They’re also one of the most common reasons for an MOT fail.
The good news is that most tyre problems are easy to spot yourself. Here’s what to look for, what the law says, and when it’s time for a new set.
The legal tread depth
The legal minimum tread depth for a car is 1.6mm across the central three-quarters of the tread, all the way round the tyre. Below that, the tyre fails the MOT, and if you’re stopped by the police with illegal tyres you could get a £2,500 fine and 3 penalty points for each one, according to National Highways on GOV.UK.
Grip, especially in the wet, drops off well before the legal limit. National Highways recommends not letting the tread get that low, and changing tyres at around 2mm in summer and 3mm in winter.
How to check your tread
A tread depth gauge costs a few pounds from a motor factor and gives you an actual measurement. Check in several places across the width of each tyre and at a few points round it, because tyres don’t always wear evenly.
Most tyres also have tread wear indicators: small raised bars across the bottom of the main grooves. Once the tread has worn down level with them, the tyre is at or near the legal limit and needs replacing.
Damage to look out for
Look over the sidewalls as well as the tread, including the inside edge if you can see it with the wheels turned. These all fail an MOT:
- Cuts deep enough to reach the ply or cords
- Lumps, bulges or tears, which mean the structure inside the tyre has started to fail
- Exposed or damaged cords
Uneven wear
The way a tyre wears tells you something about the car. Wear on both outer edges usually means the tyre has been run under-inflated, and wear down the centre suggests too much pressure. Wear on just one edge, or a car that pulls to one side, often points to the tracking.
Tracking that’s out wears tyres faster, so if your old tyres wore unevenly, it’s worth having it checked when the new ones go on. We do tracking in our own workshop.
Tyre pressures
Check the pressures regularly and before a long journey, ideally when the tyres are cold. The right figures are in your handbook, and usually on a sticker inside the driver’s door or fuel flap, sometimes with a higher figure for when the car is fully loaded. Don’t forget the spare, if you have one.
On cars first used from 1 January 2012, a tyre pressure monitoring system that isn’t working is an MOT fail, so don’t ignore the warning light.
Tyre age
There’s no legal age limit for car tyres, and the MOT only checks tyre age on vehicles with more than 8 passenger seats, such as buses and coaches. But rubber hardens and cracks with age, even on a tyre with plenty of tread, which is why National Highways suggests checking tyre age before a long journey.
You can find out when a tyre was made from the four-digit date code on the sidewall: 2321, for example, means the 23rd week of 2021. Look out for fine cracks in the sidewall or between the tread blocks, particularly on a car that isn’t driven much.
Matching tyres
Tyres on the same axle need to be the same size and the same type of construction, so a radial and a cross-ply can’t be mixed on one axle. They also need a load capacity and speed rating that meet the requirements for your vehicle. If you’re only replacing one tyre, it’s worth matching it to the one on the other side.
The MOT and your spare
The MOT only checks the tyres fitted to the car at the time of the test, so the spare isn’t inspected. If the tester notices a problem with it, they’ll tell you. It’s still worth keeping the spare in good condition, because it’s the tyre you’ll need when one of the others lets you down.
Getting new tyres fitted
We supply and fit tyres at our garage in Barking Tye, for all makes and models of cars and light commercial vehicles. You’ll find your tyre size on the sidewall as a string of numbers and letters such as 205/55 R16: that’s the width (205), the profile (55) and the wheel size in inches (16). Give us a call with it and we’ll tell you what we can get in.
If getting to us is tricky, local collection and drop-off is usually possible, so just call to arrange it.
Useful links
- Tyres
- Common reasons cars fail their MOT
- How to prepare for your MOT
- MOT inspection manual: tyres (GOV.UK)
- Tyre and journey checks from National Highways (GOV.UK)
Need new tyres? Call our garage near Needham Market with your tyre size and we’ll tell you what we can get in.
Monday to Friday, 8am to 5.30pm.