I had a similar failure on the rear of my old 370Z, total tyre failure around the entire inside of the wheel rim. Fortunately I just made it home. Not being able to get any air into it was the first indication, and everything looked fine from the exterior.
Had to call blokes out to change it at my house, as the 370 does not have a space saver, just a tin of glue, which would obviously be useless in such a case.
The tyre guys told me that the failure occurred because I must have had consistently low (very) tyre pressure, which places extreme stress on the tyre side wall, leading to total failure due to side forces acting on the weakened and damaged tyre rim.
I remember it was kin expensive and cost me an extra 50 quid for the home visit