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I'd say 2 or 3. The more layers you put on the easier it'll be to peel off.
1 Can per wheel is more than enough. That's already 4 cans @ $30 a can = $120
You add anymore cans and you might as well respray your wheels every time you want a color change.
I got mine off ebay for half that price.
I like it and the OP must do too or he wouldn't have asked.
Its a reasonable trade off for those of us that can't afford 1k+ for new wheels.