Step 1: Bolt it on.
Step 2: Inflate it.
This assumes you have a five-bolt conversion and a five-bolt collapsible spare. You might be able to fit the tire from one of those spares onto a four-bolt steel rim--or have the center of the five-bolt collapsible spare wheel cut out and a four-bolt center welded in. Only go to a competent wheel shop for this--you don't want to "cheap out" on wheels!
--DD
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Pelican Parts 914 Tech Support
A few pics of my car:
http://www.pelicanparts.com/gallery/Dave_Darling