I haven't restored a wheel yet but I have one that's going to be treated the following way.
Lightly sand any of the shiny finish left on it. Go gently.... the wheels are fairly crumbly.
Get an epoxy resin like the boat builders use. Use a slow hardener and thin it out as much the manufacturer allows.
Drench the wheel as much as you can using a brush. Just keep painting it over and over till the epoxy starts getting a tiny bit tacky.
Wipe excess off with a rag. Let it set. After it's gone hard, place it in the oven at a LOW temp about 80C-100C for a 1/2 hour.
Mix up another batch of epoxy but without the thinners, drench and bake again.
What we have done should have completely sealed and stabilised the crumbly surface and glued any fragile bits.
Epoxy resin will pretty well stick to and bind anything at all. Using this method eliminates the need to "V" out the cracks.
Now mix up some more epoxy and add micro ballons to a soft putty cosistency and using a paddle pop stick or whatever as a spatula and fill the cracks. Spread out over areas that need filling. Let it set hard, Very carefully sand.
Keep repeating until happy with the final profile and finish.
Using the same brand epoxy paint, spray or brush on the paint.
Me personally I would go for semi-gloss or lustre finish. A very glossy finish makes it look like a restoration. You want to make it look like its been on the car for years even though you did it just yesterday.
The above comes with absolutely no guarantee....I've yet to do it......but it's the way I'm gonna do it.
