Where can I get a 4" wire wheel?

I have a 4" bench grinder. Because of space constraints in my workshop I cannot use 5" or 6" wheels. I would like to outfit my bench grinder with various 4" wheels ( wire wheels, buffing and polishing wheels, etc. so I can remove rust , clean parts, and generally refurbrish older mechanical equipment. I had several 4'' wheels a few years ago but have been unable to find any 4" parts in today's world.

Your suggestions would be appreciated