My experience has been that a compromised tire mounted in the rear is far more likely to "blow" than one in the front. The only times that I have had tires catastrophically explode on me is when the inner tube sneaks between the tire bead and the rim (improper mounting). All other flats I've had, with even the scariest looking jury-rigs and defects, go with loud "hiss" and a gradual loss of pressure. Of course it is better to replace a damaged tire, but it is rarely imperative.

IMHO
BK