I could never relate to anyone who actually has a preference of one tire over another. I've gone through 4 different tires brands/types since I've started cycling, and I couldn't really tell the difference between any of them.

I drank the kool-aid, I bought GP4000S', and yea they were good, in the sense that they rolled and didn't drop me on my ass, but I've also owned Specialized Mondo's, Conti Ultra Sports, and Michelin Lithion 2s. They all felt the same. One thing I did notice with the GP4ks was that every so often the rear felt like it was fishtailing a bit. Not sure if that was due to too little traction or "too much", as if the rocking motion of the bike was actually being translated into lateral movement.

I'm currently on Michelin Lithion 2's. Not sure how much they weigh, but after some initial concerns they performed quite well on my monday night hammer ride. Lots cheaper too.

So, for those of you who think your tires are the shiz... why? Other than being really light and maybe puncture resistant (or blessed with good luck), what is it that you look for in a tire?