Oxalic Acid works great too if you have time and a big enough tank to let something soak. I used it on a set of 1950's Rollfast bicycle fenders and it works pretty good. It's great if you're lazy and don't want to do any scrubbing.
Actually though, since you don't have to scrub the chrome you won't be scratching it. I bought a few pounds of it on ebay, it comes in powder form.
Check out this thread, this guy cleaned a set of chrome wheels that were rusty.
http://www.thesamba.com/vw/forum/vie...ghlight=oxalic
