Brake cleaner - put the bike on a stand, in neutral, covering the floor liberally with cardboard to catch the runoff. Brake fluid evaporates pretty cleanly, so there shouldn't be any real mess to clean up after it dries.
For an eco-friendly route, use 50/50 Simple Green and spray the tire until the simple green runs off. Use a brush for any stubborn stuff, and rinse with your water hose. You'll likely need to clean/lube your chain afterwards, necessitating you to clean your wheel again. :thumbup.
(Okay, EDIT - BURNOUT FTMFW!! Nah, don't worry about the rubber - you ride through petrol products on the road all the time. Mind you, I wouldn't trust a tire that's been soaking in oil for an extended time, but you should be good.)
Q!