Tyre width – the first three digits display the width of the tyre in millimetres, tyres marked 225 measure 225mm across the tread from the sidewall to sidewall.
Aspect ratio – this is the fourth and fifth digits of the code that follow the width. Aspect ratio (profile height) of the sidewall is expressed as a percentage of the actual width. For example a ratio of55 means the profile height is 55% of the width.
Radial – radial tyres come with the latter R on the markings. They are constructed with the cord piles, these are positioned at a 90 degree to the direction of travel, to give additional strength to the tyre. Most new tyres which are manufactured today are radial tyres.
Wheel diameter – the following two digits represent the actual size of the wheel rim which the tyre can be fitted too. In addition, it is the diameter from bead to bead of the tyre. For example a tyre which is marked 16 would fit on a 16 -inch wheel rim.