4 cans seemed to work for me (without doing the spare).
it's light drizzle all day today. did one side at a time (only one jack). not sure if it being real humid would have anything to do with how well it came out.
washed the rims with a sponge. did the inside (the hub, didn't want to see any silver through the spokes) and outside of the wheel. didn't try to do a bang up job on the inside though, just enough so it was mostly black.
never done this before, but i'm real happy with the results. best i can say is to do a bunch of coats, and don't rush it. i popped out the centercaps, removed the 'chrome' nissan logo and painted those too.
saw on a jeep board (apparently everyone is doing it over there) to wrap your lug nuts (if you don't want them painted) and put them in the holes when you spray the stuff on, so it won't twist and rip it when you tighten down.
took about 2-3 hours per side
1st coat, 2nd coat, you get the picture...