Sure, you could use Plasti-Dip. But unless you get rid of all that rust, it will just keep getting worse. You can maybe get away with using a wire brush wheel on a grinder and get as much rust off as you can. But the biggest worry is if there's any rust along the tire bead. If the rust gets bad enough, it can cause a leak.
I had a set of wheels one time that we're BADLY corroded on the inside and all along the bead. I'm guessing the previous owner used Fix-a-flat at some point because the outside of the wheels were spotless. It got so bad that every few months it would start leaking. I had the tire dismounted and I sanded it down as best I could, then (on advice from the tire shop guy) lathered it all up in thick grease to help the bead seal better. It lasted twice as long before it started leaking again, so I guess it helped somewhat.