Tire Valve problems of the 2003 Ford Explorer Sport

Tire valve problem - 3 blown tires in 60 days original tires purchased 1/31/2007 - car mileage 75,857 at the time of purchase 1st incident - April 12, 2008 - car mileage 91,400 (right front tire) blown tire on interstate 81 in virginia (tire replaced w/new valve) no problem determination done relative to the valve 2nd incident - April 26, 2008 - car mileage 92,300 (left front tire) blown tire on interstate 85 in north carolina (tire replaced w/new valve) no problem determination done relative to the valve 3rd incident - June 18, 2008 - car mileage 93,100 (left rear tire) blown tire one interstate 285 in georgia (tire replaced w/new valve) problem determination done revealed valve seemed to be rotted 4th tire (right rear) was check during the 3rd tire replacement - valve was "wiggled" and the tire started to leak - 4th tire pro-rated and new tire and valve was put on the car as a result of the analysis done during the 3rd tire replacement - it was determined that the valves were the root cause of the tire failures tires were michelin cross terrain SUV orwl p235/7r-16 valve numbers were not determined the only reason we investigated the possibility of a recall on the valves was based on the statement made by the tire service attendant that they had seen a few of these and they were getting reimbursed due to a faulty valve. The purchase place of the tires with the valves in question was discount tire in kennesaw georgia - January 2007 consequently, I have had to replace 4 tires (which were covered under my road hazard insurance with discount tire) and a new alignment. . . Total cost, including everything was about $150 (thanks to the road hazard insurance).