Originally Posted by canklecat

Try the Continental Ultra Sport II in 700x25 and Conti Grand Prix Classic (700x25 only) on the same rims. There are slight differences, enough that the USII will easily clear my Ironman while the GP Classic scraped the rear brake bridge until it wore down.

But the tread designs are different. The Ultra Sport II is a slick (with Conti's odd arrowhead pattern on the shoulders), while the GP Classic is a 1970s-'80s style tread with a slight raised center rib, and shallow sipes and chevron pattern on the shoulders. And the Ultra Sport II are mass produced (Indonesia, I think) while the GP Classic skinwalls are touted as handmade in Germany. I like both equally well but fitting the GP Classics can be tricky on old school bikes from an era when 700x20 were standard and 700x23 was a "fat" tire.