How to choose your inner tube
Check the information indicated on the sidewall of the tyre (diameter and width).
For example, 27.5 x 2.20 means that the tyre is 27.5 inches in diameter and 2.20 inches wide.
On the tyre sidewall you will also find the dimensions in mm in ETRTO international units. For example, 50-584 means a tyre that is 50mm wide and has an inner diameter of 584mm (approx. 27.5 x 2.00).