And is it just surface rust or are there any concerns?

Replace them with chrone rims

Its past just surface rust. To properly repair them:

Demount the tires

Remove the valve stems

Wire wheel the rust off

Determine whether you care enough to repair the rust damaged surface or not

If you do- fill, sand, and prep the surface for paint

If you dont- prep for paint

Then hit it with something duplicolour wheel paint, then clearcoat according to the manufacturers instructions

When they are 1000% cured, reinstall the valve stems and mount and balance the tires