I can't tell if that's a Magic Ratio question or a GI question.

When I convert olde MTBs for trail riding I like to go for about a 34x17, remove inner and outer rings, and adjust chainline with spacers on the freehub.

My grocery getter has 36x17 and 2.0" tires. That's pretty damn spinny for road use but that's what makes the bike fun! Easy wheelies!