> Now all we have to determine is how narrow a 31.5" tall tire would have to
> be to fit in the wheelwells with the 16"/sawzall/plastic-wheelwell setup
> without bumping into other suspension components, such as springs, etc.
> 
The wheelwells and springs are the least of it.  The rear suspension 
trailing arm is longer on the 16"ers.  The stock one will not clear a large
tire.  I have heard that the half-shafts are longer to accomodate this.
A longer trailing arm would make a longer wheelbase, too.  It looks possible
to remove the seam along the rear edge of the trailing arm and weld it
differently, gaining about 15mm.  I run 215 75 R15 tires, and there is not
much clearance now.  You might get 235's on, but it would be very tight
there.  Perhaps you should look into getting some of the trailing arms
from SDP, too.

malcolm