Mazda MPV steel rims have the same bolt circle. the lug holes need to be drilled form 12mm to 14mm  
and I'm not sure on the center hub hole though I believe it fits. (have to gethome and double check mine)
the rims are a 15Jx51/2 rim  I am not sure what the "J" offset designates 

they are usually $16 +/- at your local junk yard. 

I hear that Ford exploder.. err explorers also have  5X112mm patttern  as do Audi 5K Turbos and Mercedes (off sets are ET49mm vanagon are ET45)

just a FYI 

---- Original message ----
>Date: Mon, 18 Aug 2003 15:27:31 -0400
>From: No Name Available <Vanagonluvr@AOL.COM>
>Subject: 15" steel wheels?
>To: vanagon@GERRY.VANAGON.COM
>
>I am in search of some steel 15" wheels.
>any one have a source.
>
>Chris
>VT
>91 westy
>89 syncro westy