Originally Posted by MannyTwoTwo
... the moral of the story is don't drive around for too long with a bubble on the tire because you never know.
that's exactly right ... you never know ... a bubble is an indication of a separation of the plies in the tire ... it's a sign the tire has weakened and is not holding air as it is designed to do ... and, as you've observed, a blowout can easily occur ... and, at highway speed, that could be a fatal problem ... a tire with a bubble should be replaced ASAP ...