Tyre Sizes Explained
The number 235 on the side of the tyre shown is the width of the tyre in millimetres
The number 45 is the height of the tyre's sidewall as a percentage of the width, it's also known as the aspect ratio.....
The letter R which indicates that the tyre is a radial tyre (of which all tyres are now).
The number 17 is the diameter of the tyre in inches....