Tyres are arguably the single most important piece of equipment fitted to your vehicle, as they serve as the only point of contact between your vehicle and the surface of the road. To make things even more complicated, different cars are fitted with a wide range of different tyres - depending upon the size of the wheels, the purpose of the vehicle and the tyre type fitted. For example, the tyres on a pickup truck will be a lot different to the tyres fitted to a high performance car.

To help consumers and those in the trade understand and classify different car tyres - the sidewall of a tyre is full of information. Luckily, these numbers and letters are nowhere near as confusing as they may first seem on first glance. This guide will cover some of the most common letters, numbers and markings on a tyre - helping you understand what tyres your vehicle is fitted with and any critical information.

Tyre Markings Explained

The most important series of letters and numbers on a tyre, are those which denote the tyre's size:

215 - Tyre Width

This number refers to the width of the tyre, from sidewall to sidewall. It’s measured in millimetres.


65 - Aspect Ratio

This number relates to the height of the tyre sidewall, and is represented as a percentage of the tyre width. In the above tyre, the tyre height is 65% of the width.


R - Tyre Construction

The letter ‘R’ refers to the construction of the tyre, which in modern tyres - is almost always Radial.


15 - Wheel Diameter

The number represents the size of the wheel that the tyre is designed to be fitted to. This number is in inches.


105 - Load Index

Load index refers to the maximum weight that a tyre can carry - it’s a coded number, and you can find more information about Load Index, here.


V - Speed Rating

The speed rating is displayed as a letter, and is at the very end of the tyre markings and ratings. Again, the letters are coded - and you can find more information about speed ratings, here.