I've been battling badly rusted chromes on this Slingy rehab I'm doing. I have tried many of the suggested methods on here and most work quite well. I have not yet tried Evaporust or citric acid, but as the other guys confirm here, if the chrome is gone-it's gone. All that is usually left is a dark gray/black surface, rust free, but not nice to look at...it's painful, but maybe your best avenue is a re-chrome at a car body shop or replating shop...
What has worked for me:
Soaking in vinegar
Soaking in dawn detergent and water
Using crinkled up aluminum foil with water/cola
Soak in Whink (Walmart, etc) needs gloves keep away from eyes
Soak/wipe in CLR (need gloves, great for removing "invisible" surface rust before polishing chrome tubing on stands)
As an example, I had 2 badly pitted Slingy sticksaver snare rims that were bad, not quite as extreme as yours, but I priced re chroming. In southern PA area a replating auto shop quoted $99 to re-chrome 2 14 inch rims.
Guys also have great results-depending on part type-with using tumblers where you throw your rusted parts in a machine with some type of grit that polishes the rust off from friction with grit/stones/ground nut shells.
In your case, if those rims are must-have/irreplaceable--pay for a re-chrome. If not, like me, opt for a modern day replacement. Dean