A real nasty I found with my '85 panel when newish. The 4 original
Conti Transports were rated at 55PSI max, and I ran them at 44 rear,
38 front. Got a flat on a long trip and pulled out the Conti Transport
factory spare. It went on the rear, and I checked at next gas station
to find it was low, 36psi, so I put it up to 44. Got another 50 miles,
loud thumping started, so I stopped/checked the wheel nuts, then drove
on. Still thumping, until KER-BLAM. The spare was the IDENTICAL Conti
Transport, except rated at 35psi max! They sure fooled me. Only way to
tell was the model number 77R was just 77, and by the max psi on the
shredded sidewalls. Cheap of VW, real cheap. I will only buy tires
that say 55PSI max or higher, the load capacity means squat! Tim
*********************
I'd agree with this: although I've only had the Westy 6 months, it 
came with 2 spares, and I've since bought/traded 4 more tires for the 
following list:

Yokohama 370B, load range D, 65psi max **great tire**
Conti Trans 55psi, 6ply - seems ok, good weight handling, but summer 
tread.
Conti TS750, 40psi max 'R' tire - crap! Blew one in Calif., blew 
again 2 months later (gravel road), very soft rubber, even at max psi 
they look low. I have one left out of 4 from PO bought just 1 yr 
(40k) ago!. Last flat was unrepairable.
Sears Roadhandler LT - LR C, 55psi, good stiffness, but **very** 
noisy! I will try them on the rear for the winter, but painfully 
noisy on the front at 60 mph.