John,
I don't know what year your Vanagon is (mine is an 87) but I have found  that
the belts they sell at Autozone, O'Reilly (auto parts store here in  Houston)
are
always a size too big.  This has led to much grief.  Now, I  always ask for a
size smaller than what their computer indicates ;-)  Maybe thats  another item
I should be going through the dealership to buy?
James in Houston
87 Westy