Wheel Sizes

Finding out your wheel size can actually seem like a bit of a black art with lots of complicated sequences of numbers being referred to, but it is actually very straightforward if you follow the instructions given below.

The secret is to look at the markings on the side of your tyre. A typical tyre will have a reference number on it which looks something like:

205 55 R16 91 W

(This is sometimes written as ‘205/55/R16 91 W’, by adding slashes between the main sections)

So, how do we interpret this reference number and get to the size of the wheel?

The first number is the width of the tyre in millimetres, in this case 205mm.

The second number is the height of the tyre sidewall as a percentage of the width. In this case 55% of 205mm. Fortunately you don’t need to know this number for our purposes.

We then have the reference ‘R16′. This is the key code that we are looking for, and we are actually only interested in the number. The ‘R’ character means that the tyre is a ‘radial construction’. The number following the ‘R’ is the diameter of the tyre’s inner rim in inches, which is exactly what we want to know.

The next number, ’91’, indicates the load rating for the tyre. The tyre manufacturers use a standard lookup table for the load rating and in this case 91 equates to 615kg.

Finally we have the ‘W’ character, which indicates the speed rating for the tyre when operating under full load. This is similar to the load rating in that it refers to a standard lookup table used by the tyre manufacturers and ‘W’ corresponds to 168mph.

So there you have it, a quick guide to tyre sidewall references, most of which you do not need to know when getting your alloy wheels refurbished.