How to read a tyre sidewall: every number and letter explained
The sidewall of a tyre tells you its size, how much weight it can carry, how fast it can go and how old it is. Once you know where to look, it takes about ten seconds to read.
Here is a typical car tyre marking, the kind you would find on a family hatchback:
We'll go through it piece by piece, then cover the smaller markings you might spot.
1. Tyre size: 205/55 R16
This is the most important part, and it must match what your car is approved for. You'll find the correct size in your handbook, on a sticker inside the driver's door frame or inside the fuel filler flap.
| Marking | Meaning | In our example |
|---|---|---|
| 205 | Width of the tyre, wall to wall, in millimetres | 205 mm wide |
| 55 | Profile (aspect ratio): sidewall height as a percentage of the width | 55% of 205 mm = 112.75 mm tall |
| R | Radial construction. Almost every modern car tyre is radial | Radial |
| 16 | Wheel (rim) diameter, in inches | Fits a 16-inch wheel |
A lower profile number means a thinner sidewall. That's why a 225/45 R17 looks sportier than a 205/55 R16, even though their overall height is almost the same. You can check how close two sizes are with the tyre size comparison tool.
Van tyres often have a C after the rim size, such as 215/65 R16C. The C means "commercial": a stronger tyre built for heavier loads. Don't swap C tyres for car tyres on a van.
2. Load index: 91
The number after the size is the load index. It's a code for the maximum weight each tyre can carry when inflated correctly. It isn't the weight itself, so you need a chart. Some common values:
| Load index | Max load per tyre |
|---|---|
| 84 | 500 kg |
| 87 | 545 kg |
| 88 | 560 kg |
| 91 | 615 kg |
| 94 | 670 kg |
| 95 | 690 kg |
| 97 | 730 kg |
| 100 | 800 kg |
So a 91 tyre can carry up to 615 kg, or about 2,460 kg across four tyres. Replacement tyres should have a load index at least as high as the one your car was designed for. Going lower can affect your insurance and your car's handling when loaded.
3. Speed rating: V
The letter after the load index is the speed rating: the top speed the tyre is built to handle at its full load.
| Rating | Max speed |
|---|---|
| Q | 99 mph (160 km/h) |
| R | 106 mph (170 km/h) |
| S | 112 mph (180 km/h) |
| 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) |
You'll never legally drive at these speeds in the UK, but a higher rating usually means a stiffer, more heat-resistant tyre. As with load index, replacements should match or beat the original rating. Winter tyres are a common exception: a lower rating is often allowed, but check with your insurer.
4. DOT date code: 2321
Look for the letters DOT followed by a string of letters and numbers. The last four digits tell you when the tyre was made: the first two are the week, the last two the year.
The full code may only appear on one side of the tyre, so check the inner sidewall if you can't see it. Pop the four digits into the tyre age checker to see the exact age and when to replace it. This matters most for spare tyres, cars that sit unused and part-worn tyres, which are often older than they look.
5. Other markings you might see
| Marking | What it means |
|---|---|
| XL, Extra Load or Reinforced | A stronger tyre with a higher load index than a standard tyre of the same size. Often specified on heavier cars and EVs. |
| M+S | "Mud and snow". The tread is designed for some mud and snow, but on its own this is not a proper winter tyre. |
| Mountain with a snowflake (3PMSF) | The tyre has passed a standard snow performance test. Found on winter and many all-season tyres. |
| RFT, ROF, SSR, ZP and similar | Run-flat tyre. It can keep going for a limited distance after a puncture. Different makers use different abbreviations. |
| Arrow + ROTATION | Directional tyre: it must be fitted so it turns in the direction of the arrow. |
| OUTSIDE / INSIDE | Asymmetric tyre: the marked side must face out (or in). |
| TWI or a small triangle | Shows where the tread wear indicators are. These raised bars in the grooves sit at 1.6 mm, the legal limit for cars. |
| E + number in a circle (e.g. E11) | The approval mark, showing the tyre meets the UN ECE standard. The number is the approving country. |
| MAX. PRESS or MAX. INFLATION | The highest pressure the tyre can safely hold. This is not the pressure to run it at. Use your car's recommended pressures instead. |
| TUBELESS | No inner tube needed. Standard on modern car tyres. |
| PART-WORN | A second-hand tyre. By law this must be marked in capitals at least 4 mm high. See the part-worn tyre checker. |
You may also see a model name, a brand-specific code showing the tyre was approved for a particular car maker, and on some tyres a "treadwear" number. Treadwear grades come from a US system and aren't comparable between brands, so don't rely on them.
Quick checklist when buying tyres
- The size matches your car's approved size (or is an approved alternative)
- The load index and speed rating are the same or higher than the original
- Both tyres on the same axle are the same size and type
- The date code shows a reasonably fresh tyre. New tyres are often up to a year or two old, which is normal
- If buying part-worn: there's a permanent "PART-WORN" mark and at least 2 mm of tread