>I just bought a set of reinforced Michelin X tires for my 86 Westfalia. 
>The max tire pressure is 40 psi, yet the sticker on the door calls for 48 
>psi in the rear tires. The dealer (Wheelworks, a large chain in the SF Bay 
>Area) insists that they are the correct tires. What's going on here?

The correct tires are the ones that can be inflated to the recommended 
level.  The Michelins will work acceptably at 40psi (provided you are 
*sure* they're reinforced. They must be "C" load range or better.) But he 
really should have sold you tires that could handle the 48 PSI.  Several 
manufacturers (including, I'm almost positive, Michelin) make tires that 
are rated to handle 48 psi.  I bought Bridgestones that can handle more 
than 48 psi for my '85 Westy without any problem.  Check the archives.
-Ron Salmon
 The Bus Depot
 http://www.busdepot.com