I have a Brand New 700 x 28c Conti 4Season mounted on a DT Swiss RR 1.2 Rim and it measures 25mm with a digital calipers. A little narrower than I wish, wish it was a true 28mm tire but I've had great luck with these tires. 2 sets, 4200 miles, 1 flat from construction staple, commuting through city and country riding.