i have a super RARE inflatable/collapsable spare tire..for the vanagon/bus..
it will fit in your overhead poptop luggage rack!!
its never been used.  and yes, its a STOCK VW part. the rim is stock full
size also, not a "donut". its designed to carry the weight of a westfalia
(thats what it was from).
this way you can have 2 spare tires on board. inflates with a regular bicycle
pump that operates off your cig lighter (they sell them anywhere)

email for more info-
chris