> I doubt the shop can support failing inspection for the wrong tires.

I know of other VW shops PA that have failed Vanagons for using underrated (passenger car) tires.  I have been led to believe that it is grounds for failure (PA inspections being relatively stringent). However it is rarely enforced because mechanics who don't know Vanagons don't know the difference. I once had an inspection mechanic at a national brake franchise try to test emissions by putting the wand in the gas heater tailpipe on my Bus. He looked very perplexed by the readings. World's first zero-emissions vehicle!  

Ron Salmon
The Bus Depot, Inc.
www.busdepot.com