there were inflatable space saver spares made for the '74-'75 westys.  i had 2.  they came w/ a pump to inflate them, that plugged into the "silver socket" on the dash.  deflated, this tire would fit in the cabinet under the sink.  they were mounted on a stock vanagon/bus rim. they were made by Michelin of germany.  
they are very rare now, but all '74-75 westys originally had them, and its the same wheel as the vanagon.

chris