Those rims clear coated? if not then get some good aluminum polish. Be prepared for some elbow grease, that should take the stains out. If they are clear coated then use some PB Pro-Polish you are trying to take a bit of the clear off. I'd finish them with a sealant to protect them, it helps to cut down on brake dust, as well as makes them easier to clean
On the clay if you have never clayed the car, you will be quite surprised about the results and what is on the car that you can't see.