Tyre size calculator


If you are thinking of changing the size of your car tyres, or are planning on buying a new wheel/tyre combination then it is important that you use the tool below to ensure ride height and speedometer ratings don’t change drastically. We would also recommend checking the guidelines set out by your car manufacturer and your car tyre manufacturer.


What is my tyre size?

Your tyre size can be found on the sidewall of our existing tyres and is a series of numbers and letters that looks like the diagram below. When looking for your tyre size it is important to note down the size of both the front and rear tyres as many cars have been designed with two different sizes.

















Changing tyre sizes


When considering changing wheel and tyre sizes, it is important to maintain a diameter that is as close as possible to the original so that the gearing of the drive train is not adversely impacted. Doing so will also ensure that the ride height will not change significantly.



Tyre Width     Width of the tyre in millimetres


Tyre Profile    Height of the tyre sidewall as a percentage of the width. In this case 65%                               of 215mm. Also know as the aspect ratio.


Wheel Size      The diameter of the tyre’s inner rim in inches


Load Rating    Indicates what weight each tyre is able to carry. In this case 95 on                                            the Load Index is 615kg.


Speed rating   Indicates the maximum speed for the tyre when at full load. In this case                              H on the Speed Index means 168 mph.