>>>And how would you calibrate the speedo on the van?

Sent it to someone like Hollywood Speedo or another
outfit that works on VDO gear.  They can set it to be
accurate from the factory default specs or you can give
them revs/mile of the actual tire you are running and
they can dial it in to that.  Had that done on a 911
speedo.  I just let my Vanagon speed read low--that is,
60 is really ~66, from timing mile posts.

                                Richard A. Jones
                                Boulder, Colorado
                                '81 Vanagon  Mr Bus