I have a 1994 cadillac eldorado and I want to change the 16in tires on aluminum rims to 15in steel rims. Is this possible. and if so what type of rim will be interchangable?

 

I think it is possible with some aspect because aluminium is a soft metal and bend with more stress.If you want to convert i to steel rims with an minor inch difference so it done with some effort.Designs are different you can search it.

 

Here's a link to help you find the right tire size in the new diameter so your speedo is still accurate.

Tire Size Calculator - Compare Tire Sizes