"In my experience, Maine Guide Boots fit about half a size larger, similar to how Red Wing's mostly fit for me. I know some people find a full size down in Red Wings is appropriate, but I never found that to be the case. The same situation applies for the Yuketens (including the Maine Guide Boots) I've worn/tried on."
https://www.reddit.com/r/goodyearwelt/comments/1sg0cw/does_anyone_have_experience_with_how_yuketen/