I ride a '06 LeMond Reno. The Zurich is spec'd with 25's, as is my Reno. I have Michelin Pro 4 tires- 25's-on it which leaves 3/8" clearance to the seat tube. Now, those tires actually measured out to 28, so if your geometry is similar, could use 28's-if the tires you use are true to size. BTW-that is a very nice frame! Have fun building iit up.