View Here : Tire Size Meaning
Nowadays, bicycle tire sizes are all marked according to ETRTO (European Tire and Rim Technical Organization) standard. However, older English and French tire size dimensions are still used as well. The ETRTO size specification 37-622 indicates the width of 37 mm and the tire inner diameter of 622 mm.
Tire Width is the is the width of the tire, measured in inches, when the tire is mounted and inflated to the recommended pressure. Rim Size is the outside diameter of the rim, also called the wheel size, same as in the metric size.