I have seen dramatic variations in tire sizes, but I have generally found Contis to be smaller than others. For example, I have traditionally been restricted to 700Cx25 on my Bianchi, but I currently have Continentals which are labeled 700Cx28. There is no way I could put 700Cx28 Specialized Armadillos on this bike. Bead inside diameter is about the only consistent dimension in tire sizing.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069