The Toyota steel wheels have a lousy design with the groove all the way around the wheel and visible thru the wheel openings. This groove holds water no matter what and combined with minimal paint at factory, leads to early rusting. That area on my ol' '98 was getting real bad before I traded it. I bought Highlander steelies for my snows on the '05 and although a different design than the RAV, they too have the groove!!! ......so I painted the wheels, front and back, before mounting the snows....see Album.
I'll probably paint them again before next winter, just to fend off the rust..........I think it's the only solution.....