The important thing with any MFWD is the lead/lag ratio between the front and rear axles.  Either your owner's manual or your dealer should be able to tell you what this is.  Then you can compare tire heights to determine what tires will work.  The front axle on most if not all MFWDs is running 3-5% faster than the rear, by design.  When you start looking at tires, you can compare the SLR (Static Load Radius) between the rear tires you have and the front tires you are considering.  This information is usually listed in a manufacturers book and should be available to your tire dealer and probably can be found online.  New front tires with worn rear tires will change things a little just because the rears will not be at full spec.  Probably it won't be enough to be a problem, but you can always measure your radius on a hard surface, rather than going by the book values (for the current rear tires).

Good luck,

Mike