ETRTO is the European Tire and Rim Technical Organization. ETRTO was the organization that brought standard nomenclature and defined sizes to the chaos of bicycle wheel and rim sizing in the past. A while ago the International Standards Organization (ISO) took over the job of defining bike wheel standards from ETRTO so you will see bike wheel sizes stated as ISO sizes which are identical to the older ETRTO sizes. So an ISO 622 rim is the same as an ETRTO 622 rim.
Last edited by HillRider; 09-15-20 at 06:59 PM.