How to decode the markings on a tyre.
Learn to decode the letters and numbers engraved on the sidewall of your tyres. You will need this information when it comes to changing them.
The technical characteristics of a tyre are indicated on the outer sidewall, and on some tyres, there is additional data specifying the technical characteristics and approvals for the tyre model. When choosing your tyres, it is important to know the meaning of these codes.
Dimensions and performance
- 205 : width of the tyre in millimetres. The higher the figure, the wider the tyre and the more stable the vehicle.
- 65 : ratio of the width of the tyre to the height of the sidewall. Here, the height of the tyre is 65% of its width.
- R: indicates a radial tyre, crossply and belted crossply tyres are denoted by a dash – instead of the R.
- 15 : diameter of the rim to which the tyre should be fitted, expressed in inches.
- 91 : Load Index, indicates the load that the tyre can carry at its highest speed.
- V: Speed Index, indicates the maximum speed that the tyre can reach.
- Brand: name of the tyre manufacturer.
- Model: name of the range.
- Tubeless: tyre with an integrated airtight liner, hence without an inner tube.
- M + S: indicates a mud and snow tyre.
- Reinforced: indicates a reinforced tyre (with a higher load index).
The DOT number (Department of Transport) is the tyre's fingerprint. It means that the tyre meets the safety standards set by the American ministry of transport. In particular, it indicates the place and date of manufacture.
Manufacturers such as Porsche or Mercedes have developed specific tyres for some of their ultra high-performance vehicles. Markings specific to the manufacturer are visible on the sidewall.
- N0, N1, N2, N3: Porsche, VW Touareg
- C1: Chrysler Viper
- K1: Ferrari
- B: Bentley Continental GT
- MO1: Mercedes SL 65 AMG
- RO1: Audi Quattro, RS6, RS4, R8