justcrankn

The smaller tire will generally have less rolling resistance when properly inflated. Comparing different size tires at the same PSI is silly. I have a 30mm tire with 70psi max and a 25mm with 120 psi max. Would you compare these tires using 70 psi in both?
Keep in mind there is a lot of variance in tire sizing. My 28mm Gatorskin measures an actual 26mm and my 25mm ProRace measures 27mm. This are the smallest we can use without major problems with pinch flats, cuts, and punctures. With our less expensive winter tires the bike feels like a slug, so I think the premium tires (like the Gatorskin and ProRace) are worth the extra money.