When I decided to paint my rims, I struggled with whether to remove the tires or not. When I weighed the process of disconnecting the brakes and potentially killing myself at a later date due to my own mechanical ineptitude, I smartly decided to leave them on and just tape and cover the Hell out of everything. The masking process took a stupid long time to do, but luckily I used to stripe and prep aircraft for paint back in tha day, so it didn't take as long as it could've.
Here's some in-process pics;
And here's the finished product - I'm really happy that I decided to go with the deeper red. It's not a perfect job, but for $25 in materials and about 3 hours into it, I think it's spectacular!