In Europe the following methods are used to indicate the tyre size:
•The size in mm according to the European ETRTO standard, for example 47-622, where the first number indicates the width of the inflated tyre and the second the inside diameter in mm.
•The size in inches with two numbers, for example 28" x 1¾", where the first number indicates the outside diameter of an inflated tyre in nominal inches and the second number indicates the height from the bead to the top as well as the width.
•The size in inches with three numbers, such as 28″ x 1⅝″ x 1⅜″. In this case the second number is the height and the third number is the width.
The European ETRTO standard has been used in the industry since the 1980s, but is only slowly being carried through to general parlance. Old indications usually cannot be translated into metric sizes.