I am keenly interested in this topic as well. I'd like to increase tire
height without necessarily increasing width. After inspecting my van this
weekend, it seems the limiting dimension would be clearance between the
front of the rear tires and the suspension member. By my estimation, if
width was not increased from my current 205/70R14's width, it would seem
that a tire of nearly 29 inches would be possible, though leaving only about
an inch of clearance. Brent's tires at 28.9" would come close to the maximum
as far as I can see.

For a handy tire data comparison calculator, go to
http://powerdog.com/tiresize.cgi .

I'd also be curious if anyone has definitive info. about what 15" or 16" x
5.5" or 6" *steel* wheels would be available to fit the Vanagon bolt/offset
without modification.

Doug Fitz-Randolph
Yarmouth, ME
'90 Syncro