Tire Sidewall problems of the 2004 Saturn ION

I own an 2004 Saturn Ion 3 that came with firestone, firehawk gta tires and the size is p205/55r16 89h m+s. I had an oil change and tire rotation at 6,000 miles. On 3/3/2005 I had a blowout while driving on the expressway. This was at nine at night and I had forgotten my cellphone and was made late for work. With semi's driving by at 70 mph on I-75 I was in fear for my life while changing the tire. On 3/4/2005 I called the Saturn dealership and asked them if they had the tire and how much etc. They transferred me to service and they said to bring the car in. I was happily surprised since this was Friday at noon. They inspected the tire for punctures (found none) and I think they were surprised at the sidewall separation. They replaced the tire under warranty (no charge). The tire had 9,000 miles at the time. While driving down a side road at 30 mph I heard a clunk and thought snow was hitting the tire. This then quieted down. I got on the expressway and went two miles before I heard a noise that I thought was a helecopter overhead. I pulled over and found the tire had blown out. Now I don't feel safe driving on the expressway in my new vehicle.