I put this set of Michelin Krylion Carbons on about 500 miles ago and had my first flat two days ago. It had just rained and all the road junk was sticking to my tire. I actually had to dig out the embedded shard of stone that was lodged in the tire. They are also starting the "square off" considerably. I ride at maximun PSI and am wondering if this tire need to be replaced or if I should continue to ride on it? I was thinking of replacing them with either the Vittoria Rubino Pro Slick or the Continental Grand Prix 4000s.