I've always put them on the rear (unless fwd). No steer is bad, no stop is worse.
So, say I've got a pair of 'real' chains that came with the jeep and a pair of 'cable' chains from my last truck. Both will fit over the 235/75/15's if need be. I hope it doesn't come to it, but would you mix them if conditions got bad enough? Maybe cables up front (to clear brake lines) and 'real' chains out back? Never really thought about it til I ran across the cables in the garage the other day.