If your prep is good, and you use a good quality etch primer, there is no reason that it shouldnt last 2+yrs, try and get some heat into the wheel before painting, means that you can get the paint on wetter, with less chance of it running

If I refurb a wheel that has polished edges, I never lacquer the bare alloy, far better to autosol every now and then.. when the lacquer chips, you get water and salt off the road trapped under the surface, doing far more damage! protect the polished surface with a smear of vaseline when the weather is bad
Powder coating is obviousley more durable, but it does have its drawbacks, if the wheel gets damaged repair is often more difficult due to the nature of the product, and of course it costs more than haveing ago yourself

Tom