well, if you think about it... staggered with the wider tire in the rear would be pointless on a fwd car for obvious reasons....you stagger to get better traction.
SO, if that were the case, you would stagger so that it would favor the front, wider tire in the front, but then the rear wouldnt have as much traction as the front in turns, and could kick out, spinning your car out and possibly hitting something.
SSOO, the best fitment (i would say) for a fwd car would be to have the widest you could go all around, and staying the same tire width for optimal traction and handling.
but thats for performance oriented ****. if you do it just for looks, then its whatever....but i think doing staggered with a 215 and a 225 tire would be pointless, cuz theirs not much difference in the width and you should just save the time/money at that point.
just my $0.02