Unless you're doing some serious braking the wheels don't get that hot. I Plasti-Dipped the wheels on my 240sx Drift car and heat hasn't been an issue but rock chips have. This stuff peels off realativily easy and I wouldn't suggest for long term use. As 2nd poster stated if you wanna do a good job that'll last pick up some quality supply's and do the job yourself and still save money.
Btw, if you still decide to use Plasti-Dip we've got tons of threads where people have done their wheels and what not. Check em out.