Should I paint inner fenders - if so, prime only or more......?

I've got some steel aftermarket fenders for my vehicle and they are in the typical black finish like most OEM parts. I want to make sure they don't rust. Should I have them fully painted on the backside or would a primer/sealer be sufficient?

I had an aftermarket fender on my S-10 with that typical black finish and I drove around with it for almost over a year and it didn't rust on the outside or on the inside. It's pretty much up to you. Some primer or sealer prolly won't hurt it.

bump.....anyone else?

Yeh,aftermarket parts you gotta watch,most are PPG coated and salt tested to a number of hours but ALSO reccomend priming before paint or sealing before paint....anytime I have a part that I want to stay that typical black,but want it to last(like an inner fender) I shoot it with "hot rod black" or any type of semigloss black singlestage or spraybomb