Tyre sidewalls look like a wall of code, but each part tells you something specific. Take a size like 205/55R16 91V as an example.
- 205 — the tyre's width in millimetres, measured sidewall to sidewall.
- 55 — the aspect ratio: the tyre's sidewall height as a percentage of its width. Here, the sidewall height is 55% of 205mm.
- R — construction type. R means radial, the standard construction for almost all modern passenger and light truck tyres.
- 16 — the rim diameter in inches that the tyre is designed to fit.
- 91 — the load index, showing the maximum weight the tyre can carry (see our Load Rating & Speed Rating guide).
- V — the speed rating, showing the maximum sustained speed the tyre is rated for.
Other markings you might see
- C after the rim diameter (e.g. 195R14C) — a light commercial tyre, rated for higher loads than a standard passenger tyre of the same size.
- M+S or a mountain/snowflake symbol — indicates a mud and snow, or all-weather rated tyre.
- DOT code — a series of characters ending in 4 digits (e.g. 2324) showing the week and year of manufacture — here, week 23 of 2024.
If you're ever unsure how to read your tyre's markings, bring it in and we'll walk you through it.