I really appreciate the helpful replies! It's a great forum.

Everything was clear except one point:
BTW you might also notice the ISO size designations which would be something like 40-559 or 25-622, which would 26" and 700c respectively.

Does 40-559 mean a 26" wheel/tire with a 40mm tire width?
Sorry, it's probably because I'm a beginner.

I'll keep reading the forum. Hope one day I can offer advice!
Thanks!