When choosing the right inner tube, you should make sure that the tube is intended by the manufacturer for the tyre diameter and width. As a rule, bicycle inner tubes always cover a size range because they are relatively flexible.

Different size specifications are common for tyres and inner tubes:

- The classic specification in inches (diameter x width) : e.g. 28 x 1.25

- The more modern ETRTO specification in millimetres (width - diameter): e.g. 35 - 622

- Alternative size designations: e.g. 700C