Bundt's were made in 15", but they are very rare. I've had a few of them and the center cap seat if quite weak: both of mine were ruined when removing the tire on it.
For everyone's info I bought a set of ALLOY wheels with the lugs and hubcaps in great shape today with two so-so tires and two bare for under $100. No performance decrease and personally pleasing for my wife's w123 300TD.