Greetings all.
Thanks for the info you provided. With it in hand I removed each of my rims this week and cleaned and polished them. My SRT has 16k miles and this was the very 1st time the wheels had been removed and cleaned, so they still had a lot of undercoating overspray on them. Much as noted in previous comments, the SRT6 rims are clear-coated, front and back, and whatever the clear-coat is, it's one pretty darn tough paint! I've always used Westley's Bleche-white in the past to clean tires and rims, but as the warning says, it is somewhat corrosive, so I've always tested it on everything that I use it on, just in case... So what i did here was isolate a 2 inch by 2 inch square area on the inside of the first rim with some painters blue tape, and i then put a good coat of Westley's on it for 1 minute to see what might happen... Well, I'm happy to say that absolutely nothing at all happened to the clearcoat, and that it didn't even soften. But what it did was leave the rim absolutely spotless! (see pictures) So here's my procedure:
1. put car in park and chock the 3 tires not being removed.
2. slightly loosen wheel lugs of the rim that you're gonna remove.
3. using car jack lift vehicle and remove tire/rim.
4. spray entire inside and outside of the tire and rim with westley's bleche-white.
5. let it stand for 30-40 seconds and then use a painters brush to mop all the bleche-white around and to help loosen up the grime.
6. spray the entire tire with a garden hose and then scrub the tire/rim with a soapy wash mitt to neutralize the bleche-white and clean the tire/rim. if you have a very stubborn area with undercoating on it, like i did, just spray it again with the westley's, let set, and then use a fingernail scrubber to remove it. then rinse and wash again, per above.
7. sun dry or towel dry and then apply your favorite wax. I used meguiars gold class on my rims and they turned out great.

Potential gotchas: when spraying the bleche-white or whatever product you use, be sure that your car, or anything else for that matter, isn't around or downwind of the spray, which is typically corrosive. have your garden hose at ready just in case.

thanks again for your help, and best regards to all -- Bob