Hammerite Green thats pretty hard, Would look ok if the rest of the car was green, Failing that Powercoating is the best method, do a google for your nearest company and get some quotes
Another vote for powder-coating. Just had my alloys done for £60 a wheel at a franchise of The Wheel Specialist - do an internet search for the one nearest you.
Delivered the car early a.m., they removed tyres, did wheels inc baking in oven, refitted tyres and got the car back late afternoon.
I was joking about hammerite Like a bit of red oxide and some Varnish should do a good job, or a nice powercoat finish, Google has loads of places that do it, and some of the wheel refurb companies come to you