Must have been some boom. The hole is on the thread side, good amount of tread left on the tire. Now it's got layers of thread and that forced it's way through.

I talked to a couple of tire dealers, to see if I can get anything under warrenty. Nope. The only explation I've had that makes some sense is that the tire was dry rot and weak. The good thing is this didn't happen while I was cursing on the highway. I would have been on the rim and airborn. The bad news is that waltmart had a huge clearance of tires a week ago, and I missed a bargin.