How to read a tyre sidewall
The side of a tyre tells you its size, how much weight it can carry, how fast it's rated to go, when it was made, and which way round it goes. It also carries a pressure figure that catches a lot of people out. Here's how to read it, using a common size as the example: 205/55 R16 91V.
The size and rating
| Marking | What it means |
|---|---|
| 205 | Width: 205mm, measured from sidewall to sidewall. |
| 55 | Aspect ratio: the height of the sidewall as a percentage of the width. Here that's 55% of 205mm, about 113mm. |
| R | Radial construction, the usual type for car tyres. |
| 16 | Rim diameter: it fits a 16-inch wheel. |
| 91 | Load index: the most each tyre can carry, here 615kg. |
| V | Speed rating: the top speed the tyre is rated for, here 149 mph (240 km/h). |
A lower aspect ratio means a shallower sidewall. On high-performance tyres you may see ZR in place of R, which marks a tyre rated for more than 240 km/h (149 mph).
Load index
The load index is a code, not a weight. Each number stands for the maximum load one tyre can carry. A few common ones on cars:
| Load index | Most each tyre can carry |
|---|---|
| 82 | 475kg |
| 87 | 545kg |
| 91 | 615kg |
| 94 | 670kg |
| 97 | 730kg |
| 100 | 800kg |
Speed rating
The letter after the load index is the highest speed the tyre is rated for, when it's correctly inflated and carrying its load. It's a limit, not a target.
| Speed rating | Up to |
|---|---|
| T | 118 mph (190 km/h) |
| H | 130 mph (210 km/h) |
| V | 149 mph (240 km/h) |
| W | 168 mph (270 km/h) |
| Y | 186 mph (300 km/h) |
When you replace a tyre, match the size, and fit a load index and speed rating at least as high as your car maker specifies. Your handbook gives them.
XL and reinforced
XL stands for Extra Load. You may also see Reinforced, RF or HL. These tyres have a stronger structure, so they can carry more than a standard tyre of the same size and have a higher load index. They're designed to run at higher pressures to carry that extra load, so use your car maker's figures for the tyre fitted, and the separate XL figure if your handbook gives one.
Run-flat markings
There's no single industry code for run-flat tyres. Each maker uses its own, so look for markings such as RFT, ROF, SSR, ZP, ZPS, DSST, RSC or HRS, or the words Run Flat. Run-flats behave differently after a puncture, so it's worth knowing if you have them. Here's how far you can drive on a run-flat.
Winter markings
- M+S means mud and snow. It's the maker's own description of the tread, with no test behind it.
- The three-peak mountain snowflake (3PMSF) shows the tyre has passed a standard test for grip on snow. All winter tyres carry it, and so do the better all-season tyres.
More on winter, all-season and summer tyres.
How old is it? The date code
Look for the letters DOT followed by a string of letters and numbers. DOT refers to the US Department of Transportation, but the code is on tyres sold here too. The last four digits are the date the tyre was made: the week, then the year. So 3522 means week 35 of 2022.
The full code is often only on one side of the tyre, so if you can't find it, it may be on the inner face. A three-digit code is the old format: the DVSA treats any tyre with one as more than ten years old. Here's how old is too old for a tyre.
Which way round
- Directional tyres have an arrow, sometimes with the word ROTATION, showing which way the tyre must turn when the car moves forward.
- Asymmetric tyres are marked OUTSIDE and INSIDE, because the tread is different on each half. The side marked OUTSIDE faces out.
Fitting a tyre against its sidewall instructions can fail the MOT. More on tyres and the MOT.
Other markings
- TWI marks where the tread wear indicators are: small bars in the bottom of the main grooves at about 1.6mm, the legal limit for cars.
- An E in a circle with a number shows the tyre is approved to European standards.
- The tyre label isn't on the sidewall. New tyres sold in the UK come with a label, shown where you buy them, that rates fuel efficiency, wet grip and external noise.
The pressure on the tyre isn't your pressure
Near the rim, often in small print, you'll find a maximum load and a maximum pressure, usually marked something like MAX. PRESS. with a figure in kPa and psi. That's the most the tyre should ever be inflated to. It isn't the figure to use.
Pump a tyre up to its maximum and it's over-inflated: a harder ride, less grip, and wear down the middle of the tread. Here's what over- and under-inflation do. The right pressure depends on your car and how loaded it is, not just on the tyre. Your car's figures are on the label in the door frame or fuel flap, in the handbook, or you can look them up by registration.