Yeah, what he said...

Long ago and far away, I managed to pry a 26 x 1 3/8" EA3 tire onto a 26 x 1 3/8" S-6 rim. This so impressed the head mechanic at the local bike shop that they eventually hired me. Thus began my 12 year career in the bicycle business.

FWIW: an EA3 rim is about 7mm smaller in diameter than a S-6 rim. That tire I pried on? It had to be taken off with diagonal cutters.