I saw a post on another web site about this product.It is a masonry cleaner,really powerful stuff.It is made by Prosoco, Sure Klean 600.I just bought some and it is the best $16.00 I've ever spent on a wheel cleaner.This stuff will remove baked on brake dust with very little effort and it does not harm the clear coat on the rim.I just used it on 4 Volvo hub caps that had 17 years of caked on brake dust and I was able to remove all of it!I did 4 hub caps in about an hour and a half.Note you must wear gloves,I used dishwashing gloves,nothing special.Also work outside,well ventilated,no indoor use.For the stubborn spots I used a small piece of wood to scrape break the bond between the cap and cleaner.I used a shop rag to scrub 3 hubcaps.On the last one I tried a "blue" scotch brite sponge,it does not scratch,worked just fine.I then tried it on a section of a "Corona"rim.That section looks new!I did not finish the rim because the cars is being sold and will be gone tomorrow.There was no damage to the clear coat,zero.
You can buy this stuff at any masonry supply store or google prosoco sure clean and find a dealer near you.That is what I did.
I posted on turbobricks looking for the person who made the original post.He showed a pic of the Volvo rim that came on the 240 classic and the wheel looks new.Like the original poster,I have tried everthing to remove baked on,caked on brake dust with no success.This stuff works!Im not good at posting pics but I did get one of before and after hub cap.You can email me and I will send it you and you can post here for me and others to see.
Thanks,Nelson