I recently got back from vacaction and one of my tires was flat on my 03 WRX sedan. I am still running the stock RE04's. I put on the spare and took it down to my local tire shop. They told me that the tire wasn't worth patching up and then showed me that the insides of both front tires were almost totally bald. They said I need a new alignment now. The car is about a year old and has 12K miles on it. What might have caused this problem and how can I prevent it from happening again? Any feedback would be greatly appreciated.