What is the best way to preserve hubcaps?

[chev-obsession]

I bought these hub caps and they have some rust issues on the back sides. I want the fronts to stay the way they are as they fit the rest of the trucks patina nicely. There is a small spot on one of the caps where the rust is starting to flake off.

I don’t think I want to media blasted them, then I thought vinegar but that might eat through the caps which I don’t want either. Any other idea that you guys would have? Something maybe non invasive? What do you guys do to stop the rust of your hub caps?