Well I know that they bake parts at 400 degrees for 8 to 10 mins. at a time for each coat. I have had my toyota tacoma wheels powder coated for a year now and had no trouble out of them what so ever and its a 4x4. I also had some motorcycle wheels coated and have had no problems out of them either. A good rate is $100-$150 for a set of 4 wheels up to 18inches. If they are trying to charge you over $150 they are charging to much! Note: you can also powder coat center caps as well (if you have them like on a truck or something of that nature) just dont go over 250 degrees and dont leave them in for more than 5 mins. keep a real close eye on them.