My '03 Trek 520 came with Kevlar-belted Bontrager tires. I had a couple flats within 2-300 miles, and the sidewalls seemed very flimsy. I dumped them in favor of Continental Top Touring tires, and now use Vittoria Randonneur tires.

I have some low-end Bontrager 700x25c tires on my Trek 1200 road bike, but I use a Mr Tuffy liner on those.