Tyre Code

What does tyre size mean?

To the untrained eye, the side wall of a tyre can look like a meaningless set of numbers, letters and symbols. Hidden amongst these is the tyre size. But what does it look like and, more importantly, what does it mean?

Dissecting the code

The tyre size might read like this: P195/55 R16 87 V. Hardly user friendly but, when you know what it all means, you’ll realise it tells you useful information about the tyre’s construction, size and type.

       

1 Cross section width

The first three numbers, in this case 195, refer to the section width of the tyre. This is the measurement, in millimetres, from the tyre’s inner sidewall to its outer sidewall.

2 Aspect ratio

The aspect ratio, or profile, refers to the height of the sidewall as a % of the section width. In our example, 55 means the height is equal to 55% of the 195 mm width. The bigger the aspect ratio, the bigger the sidewall will be.

3 Construction type

The letter R means the tyre is a radial construction. Almost all new car tyres are radials.

4 Rim

The number to the right of the construction type is the rim diameter, measured in inches. In this case, it’s a 16” wheel.

5 Load index 

The final number is the load index i.e. the maximum load (in kg) that the tyre can carry.

6 Speed symbol

The final character (in this case V) relates to the maximum speed of use.