Example: 255/45 R20
255 is the tyre width in millimetres. 45 is the sidewall height as a percentage of the width. R means radial construction. 20 is the wheel diameter in inches.
Load and speed ratings
Numbers and letters after the size indicate the load index and speed rating. The replacement must meet the vehicle requirements.
Other important markings
Run-flat, acoustic foam, manufacturer approval, extra-load and electric-vehicle markings can affect the correct option. Send a clear sidewall photo when unsure.
Check all four tyres
Front and rear sizes can differ, especially on performance vehicles. Read both axles rather than assuming every tyre is the same.
How this guidance should be used
Vehicle manufacturer instructions and the actual tyre condition take priority. The photographs and vehicle details should be reviewed before a service decision, and the tyre must be inspected when repair safety is uncertain.
This guide is general information. A technician must inspect the actual tyre and location before confirming a repair or replacement.