I bought two sets of these:

http://www.jensonusa.com/store/produ...thon+Tire.aspx

Can't remember exactly where I bought them - but I'm sure they were this model of tire. I had trouble getting them to seat on my 700mm rims. I had to take a piece of fine abrasive and take some of the shine off the tire bead to get them to seat. The tire kept popping off the rim - thus blowing out my tube. The tire bead felt waxy and slick thats why I very lightly buffed the sheen off it with either a "green kitchen scrubby pad" or maybe 0000 steel wool, I just remember the buffing. Now the tires have been on for over a year. I don't remember having that problem with the 26" tires. Seems like they fit very tight. I beleive there's some kind of tire compound you can use to seat the tire on the rims - I don't know what it is though. Be careful when you air them up - have a couple extra tubes on hand. Hope it helps.