Happened to me in my Mustang! I was running around 80mph on hwy very scary i must say.

**off topic**

I have been hearing a roaring sound @ the rear. Alternating from right to left. I remember my front right sound like this (or wheel bearing) took it in and they said the tires were flat spotted. New tires no sound. My rear tires are near bald...could this be the cause?