Use a router and a bit with a roller guide. Flip the wheel over and use the flat surface for the router. The roller guide should be just below the lip, on the 2nd, wider surface area. Took about 1 min per wheel. I had to buy a router, so the whole operation ran me about 90$. Obviously if you own or borrow a router, it's free/cheaper.
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04.5 2500 CTD CC Shorty 4x4... K&N intake, Silencer ring removed, Muffler delete pipe