0.1 or one tenth should do the trick as i painted some ford escort wheels 15s and still had some left when id done.As for spray cans id say 2 tins to be safe.
after two good coats they looked the dogs!
just dont forget the scotch the wheels before you laqure them or the laqure will peel and look pants. also will cause oxidisation. good luck and lets see your progress after you have done it.