When buying a replacement tire, start with the ETRTO marking on the old sidewall. For example, 37-622 means a nominal width of 37 mm and an inner diameter of 622 mm. The second number must match the rim’s bead-seat diameter. The tire pictured is marked 23-622: narrower, but intended for the same 622 mm diameter.
An inch label alone is insufficient. Tires with 622 mm and 635 mm inner diameters can both be called 28-inch. Familiar 29-inch mountain-bike tires use the 622 mm diameter, too. In the designation 700C, the C also denotes 622 mm; 700 is not the rim diameter.
Matching diameters do not establish full compatibility. Tire width must suit the rim’s internal width, with adequate frame clearance. Check tire and rim manufacturers’ guidance on tire type and pressure limits. Actual tire width can differ from its nominal size and vary with inflation pressure.