Join Date: Dec 2004
Location: Middle of da Mitten
Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, homebuilt recumbent
Schwalbe Stelvios are probably the fastest tire you can get for a 406 rim, followed closely by Conti Grand Prix. I have had terrible luck with both, though. Stelvios typically separate the fabric in the casing, causing an S-shaped contact strip. Contis, on the other hand, have very fragile sidewalls - as they wear they seem to sprout more and more broken cords out of the sidewalls until finally you don't dare inflate them anymore. Bottom line, I consider either of them only suitable for racing.
The jury is still out on Conti Sport Contact, which is 28x406 (labelled, as Conti does, incorrectly as 20x1 1/8.) The only one I've gone through suffered premature sidewall failure from what looked like a brake pad cut - except that I don't have rim brakes. And I haven't decided yet if they're faster or slower than Comets.
Primo 20x1.35 is light and relatively fast; but if you get the Kevlar version, expect that feature to cost you some speed.