How to read your tyre size

How to read your tyre’s sidewall markings

Your tyre sidewall contains all the information about your tyre that you’ll need. Here’s a little guide to what all those numbers and letters mean:

A. Tyre width

The width of your tyre, in millimetres, measured from sidewall to sidewall.

B. Aspect ratio or tyre profile

This is the ratio of the tyre’s cross-section to its width, expressed as a percentage. An aspect ratio of 65, for example, indicates that the tyre’s height is 65% of its width.

C. Wheel diameter

The diameter (height) of the wheel in inches.

D. Load index

Your tyre’s load index relates to its maximum carrying capacity (in kg). You’ll find the load rating of your tyre on the sidewall, just to the right of the diameter.

For example, a tyre with a load index of 91 can carry 615kg of weight.

Load ratings and speed ratings should be looked at together when you buy a new tyre. Also remember to check your manufacturer’s recommendations.

E. Speed rating

The speed rating is the maximum speed for a tyre when it is correctly inflated and being used under load. The speed rating is the letter at the end of the sidewall, after the load index number. A tyre with a speed rating of V, for example, has a maximum speed of 240 km/h.

When buying new tyres, make sure you match their speed rating with the speed capabilities of your vehicle.