Eric,
I recently helped complete an Subie. install.  That van is running 15"
rims (Can't remember tire size) and there appears to be ample clearance.
I don't have a measurement to give you right now, but if you wish, I'll
take some measurements and get the tire size.

So there's another option for you!

John

>What about clearance?  I hear you lose a few inches with the Subie.  Is
>there any suspension adjustment to compensate or is that just not a good
>idea (or too expensive?).