Tyre codePortugal

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136. Tyre code

A tyre code is the series of letters and numbers marked on a tyre's sidewall that identifies important characteristics such as tyre width, aspect ratio, construction, wheel diameter, load capacity and speed rating. A typical example is 205/55 R16 91V.

Drivers should use tyres whose specifications are suitable for the vehicle. The required tyre sizes and ratings can normally be found in the vehicle handbook, certificate of conformity or other manufacturer information.

Tyre code
Diagram explaining the markings in a tyre code.
Wikimedia.org • F l a n k e r • CC BY
What does a tyre code such as 205/55 R16 mean?

205 indicates the nominal tyre width in millimetres, 55 is the aspect ratio between sidewall height and tyre width, R indicates radial construction and 16 indicates the diameter of the wheel rim in inches.

What do numbers and letters such as 91V mean on a tyre?

The number is the load index, which identifies the maximum load the tyre is designed to carry under specified conditions. The letter is the speed rating or speed-category symbol, which indicates the tyre's approved speed capability.

What other markings can appear on a tyre?

Tyres can carry additional markings indicating approval, manufacturer information, production date, suitability for winter conditions, reinforced construction or other technical characteristics. The exact markings depend on the tyre type and applicable standards.

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