Here’s what I did when I painted the steel wheels that came on my Subaru. I work at a tire shop, so I took all the wheel weights, the tires and the valve stems off of the wheels before I got started, but you could just as easily mask off the parts that you don’t want to get paint on.
Using a stiff-bristled plastic brush, some very hot water and some generic spray cleaner, I cleaned all the dirt and accumulated scrunge off of the outside face of the wheels. After using compressed air to dry them, I set them on some stacks of junk tires with the valve stem holes at the 12 o’clock position. I used some high temp gray primer on all the wheels, turning them 180 degrees after 3 coats. In all, all four wheels got 6 coats of primer, which worked out to right about a can and a half I think. After the primer was dry, I repeated the painting process with Dupli-Color Metal-Cast paint, blue in my case. I think I went through two and a half cans of blue paint before I was done. After that was completely dry (I let the wheels sit in the sun for most of the day) I put new valve stems back in, remounted the wheels and then balanced everything. This is my winter set of wheels, so they only get used in cold, nasty weather and the paint is holding up just fine. I wound up painting the grill on my car the same color as the wheels.
When I get around to painting my summer set of wheels, I’ll take pictures of the whole process and post up a How-To on what I used and how I did it. I’m not sure when that’s going to be though, with the weather being as cold as it is right now, spray paint doesn’t work so well.