Decode a tyre size marking

How to read a tyre marking

A passenger marking such as 205/55 R16 91V is a compact spec. 205 is the section width in millimetres. 55 is the aspect ratio: sidewall height as a percentage of that width. R is radial construction. 16 is the rim diameter in inches. 91 is a load index. V is a speed symbol.

Sidewall height is width × aspect ÷ 100. Overall diameter is two sidewalls plus the rim converted to millimetres (inches × 25.4). Those millimetre figures help you compare two markings. They are not a substitute for the vehicle plate or the tyre maker’s fitment list.

Load index and speed symbol are tables, not guesses. We include the common passenger range. If a marking is outside that table, the result says it is not in the bundled table rather than a made-up kilogram or km/h figure.

We do not offer a vehicle-to-size lookup. That data is licensed. Putting an unofficial scrape on a public marketing site would be both inaccurate and, in many cases, not permitted. If you run a tyre counter, Tyren is the product for GST billing and vehicle-based fitment inside the app — not this decoder.

Use the field below, then optionally email yourself the decode. That email is a lead with intent=tool. The size string never hits a government or OEM API from this page.

Extra load (XL / Reinforced) and LT commercial markings are not fully decoded here. If the string does not match 205/55 R16 91V-style passenger notation, the tool says so instead of guessing a rim. Plus-sizing changes speedometer error and clearance — that is a workshop decision, not a marketing-page output.