Here is the link to the jobber that supplied the wheels for our 5er.. they have a great customer svc department, maybe, even if they don't stock your wheel, they will know who does..
Tredit Tire - Tires and Wheels for RVs and Trailers
and remember (lesson taught to me as a youth trying to scrounge four matching hub caps) that they can only see one side of the 5er at a time.