I would take them back to the shop that coated them and have them deal with it. If they won't, ask them for a small jar of this:
Super Speed Industrial Paste Stripper
I would cover the wheels with tape, line the holes with PVC and plug the holes and using a syringe, put about 2cc's of stripper in each. Let it sit for 30+ minutes, pull out the plugs and carefully scrub with some kind of round head brush. Carefully rinse with water.
If you go this route, don't get the stripper on your skin for longer than 30 seconds, it kills skin and the underlying new layer is very tender for a few days. Get proper gloves or triple 6+mil nitrile for a small job is safe.