Your tyre’s sidewall contains all of the information about your tyre that you’ll need. Here’s a little guide to what all of those numbers and letters mean:
A. TYRE WIDTH
The width of your tyre, in millimetres, measured from sidewall to sidewall.
B. ASPECT RATIO
This is the ratio of the tyre’s cross-section to its width, expressed as a percentage. An aspect ratio of 60, for example, indicates that the tyre’s height is 60% of its width.
C. WHEEL DIAMETER
The diameter (height) of the wheel in inches, measured at the bead seat.
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.
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 H, for example, has a maximum speed of 210 km/h.
When buying new tyres, make sure you match their speed rating with the speed capabilities of your vehicle.