So. My roadie has Conti Ultra Sports on it and thus far I'm averaging a puncture every other ride; the last one was caused be a stone wedged into the tyre, for feck's sake. I know there are some pretty bomb-proof tyres out there, but I don't want something heavy and sluggish and all, just less likely to let me down (no pun intended) than what is on there at present. Any ideas?