[Timmeh!]

you'd have to probably buy two different sizes of the same wheel.... i dont know if its even possible from most manufacturers.........
it woould most likely look weird as well

i assume you mean staggered as in
a smaller width rim up front,
and a wider rim in the back...
the most youd prolly be able to get for a focus would be a 1/2" stagger...
and since our cars are front drive youd be better of putting the wider rims up front....
it sounds like way too much of a hassle to me.....

 

[fakehawk]

I know VW guys do it to fill the rear "fender gap" put a wider wheel out back to fill it up more.
typical sizes are 7.5-8 inch wide in the front and 9-10 inch wide in back on either 17 or 18 in diameter. (with the right offsets)
this is obviously a show thing and most that are somewhat performance oriented tend to have a "regular" set as well.
Others just use spacers in teh rear to get rear wheels to sit flush. (this puts more stress on your wheel bearings though)