Just my personal experience with glass...

1. I was washing a friends car once and when the the cold water hit the hot windshield POP! cracked in 3 places.

2. lightning, will pop and spider web glass.

3. I was drilling a hole in a patio door a while back and I miscalculated and hit the glass with the drill bit BANG! the whole door turned into thousands of pieces no bigger than a quarter inch square.

Rocks can get flung forward off of tires, never heard of it breaking a window though. Rocks usually bounce off when they hit. I've seen rocks make a hole like a bullet because of an irregular point on one side.

Just some thoughts.

 

From reading the first post about the accident from behind. That would be my guess. Probaly loosened the window and over time with vibrations and all it cracked.


VINNIE

 

What Ever happen
IT SUCKS
Sorry wkuper11

 

Vinn is probably got the right idea...I was thinking vibration as well, but kept forgetting he was hit from the rear..that had to have some sort of warping affect on something I would think

 

You're on the right track! Most likely the box hit back of the cab in the previously mentioned accident and bent (stressed) the tempered glass, causing the normally scattered molecules to line up and wait for an opportunity to exit. That opportunity presented itself due to vibration, bump in the road, bass hit from your system, etc.

I've seen it many times being in the auto body trade. Tempered glass will sometimes take a shot and explode at any given time after the hit.

Either that or someone tried to bussacapinyoass...

 

The same thing happened to me about 8 years ago. Except I was driving on a dirt/gravel road. I heard a loud pop under the front of the truck and then a split second later the rear window just shattered. Man it scared the he!! out of me! I think what happened is a rock was kicked up between the bed and the cab somehow. I think it ricochet'ed like a pinball and finally hit the back glass. I never found the rock but that was the only logical solution I could come up with....besides a sniper theory. Wow that is too weird!

Hope ya figure it out.