When you need replacement tyres for your car, van, 4×4 or motorbike, it’s easy to work out which size you will require. Simply look on the side of the tyre and check for the tyre size and specification – this will look something like this:

185/65 R 14 86T

And if we break this code down, this is what it means:

185 – denotes the normal tread width of the tyres in mm

65 – denotes the aspect ratio, which means the height of the tyre as a percentage of the tread width. If this number is missing, assume the ratio is 82%

R – denotes the kind of construction. R stands for Radial and is the most common

14 – denotes the diameter of the rim in inches (this number and the letter before it make up your Rim Size)

86 – denotes the tyre’s load capacity, relating to the weight of the vehicle (you won’t usually be asked for this number)

T – denotes the maximum speed sustainable at the related capacity (for cars, this generally falls between T and Y)

So, when you need to give these details to a tyre fitter, or when buying tyres online, you’ll be asked for:

Tyre Width: the first three numbers, eg 185

Profile: the fourth and fifth numbers, eg 85

Rim Size: a letter and the sixth and seventh numbers, eg R14

Speed Rating: the last letter in this string of digits, eg T

Not so complicated, eh? Then all you have to do is choose which tyres in this size you want, depending on price, manufacturer, and if you’re really picky, tread pattern…