One more method: Use a Dremel drum sander mandrel at very slow speed in Dremel tool. It works great on wheels secured to the axles. It's a bigger challenge with postwar wheels not secured to axles.
Set up in cradle. Use index cards cut to fit for protection against spatter.
Clean with denatured alcohol which leaves no residue. Dip folded paper towel in bowl of cleaner. Hold against wheel while spinning with the mandrel on the other wheel. If I wait too long for this cleaning I may have some grime the needs removing by hand before alcohol cleaning. I use an old paring knife that has a nice stiff blade for scraping off the grimy ridgesl
