Thought I'd jump in here. Just picked up a 2014 SR5 premium and am considering Plasti Dip for the wheels.
Anyway, I did this on my Accord when I bought it in June '13 and six months later, many car washes, snow, road salt, etc. it's holding up fantastically. Personally, I would take the wheels off the 4R in order to ensure best coverage and that the wheels are completely clean before starting. There's a video on YouTube where a guy used simple 4"X6" note cards to place in the lip between the rim and the tires to prevent overspray onto the tires. I did this as well, very simple, cheap and highly effective. Home Depot and Lowes carry the stuff or buy on amazon.
Good luck!