Supposedly, the rim bug only affects cars with different sized wheels on the front than the back. Personally, I've been keeping the stock rims unless I see that someone else is running custom rims without problems. I'll let someone else do the experiment
The Mustang GT500, for example, was fine with custom rims.
So it's up to you. If you think you're running times that are just as good with the custom rims, go ahead and use them. I'm crossing my fingers that PD will fix this soon so I can run my chrome red rims on everything