Tyre size guide
What tyre size is my car?
It’s moulded into the side of every tyre, and the sizes and pressures the maker recommends are on a sticker, usually inside the driver’s door frame. Here’s where to look and how to read the code. We can’t look sizes up by registration yet: that data is licensed, and we haven’t signed up a provider.
Tyres came up in 26.4% of failed MOTs in 2025. Enter a registration to see whether a tester has flagged yours.
Where to find your tyre size
| Tyre sidewall | The size of the tyre fitted now, moulded into the rubber. This is the one to trust when you’re buying a replacement. |
|---|---|
| Door-frame sticker | The factory sizes and pressures, usually on the driver’s door frame. Some makers put it inside the fuel filler flap or the glovebox lid. |
| Owner’s handbook | Every wheel and tyre option the car was sold with, and the pressures for each. |
| V5C logbook | Doesn’t list the tyre size, so don’t go hunting for it there. |
How to read 205/55 R16 91V
| 205 | Width in millimetres. |
|---|---|
| 55 | Sidewall height as a percentage of the width (the profile). |
| R | Radial construction, which is nearly every car tyre sold today. |
| 16 | Rim diameter in inches. |
| 91 | Load index: 91 means 615kg per tyre. |
| V | Speed rating: V means up to 149mph. |
Replace like for like on size. The load and speed ratings can go up but not down: a rating below the car’s minimum is a major defect at the MOT.
Tyres at the MOT
In 2025, 1,835,811 cars and light vans failed their first MOT attempt with a tyre defect. That’s 26.4% of all fails, and tyres were the fourth most common reason after suspension, lights and brakes.
The rules the tester applies, from section 5.2.3 of the MOT inspection manual:
- Tread at least 1.6mm deep across the central three-quarters of the tread, all the way round.
- No different sizes on the same axle.
- Load and speed ratings at least what the car needs.
- No cuts, lumps, bulges or exposed cords.
The pre-MOT checklist has the 20p tread test. If you drive an electric car, check the tyres first: electric cars fail on tyres far more often than petrol cars of the same age. The pass rates by model show how often each model fails on tyres.
Questions
Can you look up my tyre size from the registration?
Not yet. No government register holds tyre sizes. Factory fitment data is licensed from commercial vehicle-data providers, and we haven't signed one up. The sidewall and the door-frame sticker give you the answer in under a minute.
What if my car has different wheels on it?
Go by the sidewall of the tyre that's actually fitted. The door-frame sticker lists the sizes the car left the factory with, and aftermarket wheels can take a size that isn't on it.
How do I read a tyre size?
205/55 R16 91V means 205mm wide, sidewall 55% of the width, radial, 16-inch rim, load index 91 (615kg per tyre) and speed rating V (up to 149mph). Match the size exactly when you replace a tyre, and match or beat the load and speed ratings.
How old are my tyres?
Look for the four-digit date code at the end of the DOT marking on the sidewall. 2319 means the 23rd week of 2019. It may only be on one side of the tyre.
Can I have different tyre sizes front and rear?
Yes, if the car was built that way: some performance cars run wider tyres at the back. What the MOT fails is different sizes on the same axle.
MOT figures: DVSA anonymised MOT results, 2025, first attempts on cars and light vans, retrieved 12 Sep 2026. Tyre rules: DVSA MOT inspection manual, section 5.2.3. Page last reviewed 11 Oct 2026.