Had this happen when I was out on the road bike earlier:
[video]http://www.youtube.com/watch?v=E07uKBiubDU[/video]

There was a pretty loud bang when it happened and it blew one side of the tyre right off the rim. Didn’t cause any real problem where it actually happened, but a few minutes earlier I’d been descending a bumpy road at nearly 40mph, so glad it didn’t happen then!

I’ve never had a bicycle tyre actually blow-out like that before – anyone else had that happen to them?

yeah but only when the tyre hasn’t been seated properly or has one of those weird bulgy spots.. i’d check that before you go out next time!