Wheel cleaner
 

What wheel cleaner will fix my filthy E46 wheels without taking the paint off?

The generic crap I bought at auto zone did very little.

I remember nick recommended some seriously potent stuff a long time ago and it worked wonders, but I can't seem to find the thread.

Sonax

Ordered. Thanks.

Or in a desperate situation, muriatic acid. But that’s only when you’re ready to take risks.

Even with Sonax, rinse with plenty of water. It is very strong IIRC. BMW wheel cleaner (in those white bottles) may be Sonax, I'm not sure. It turns red after a minute.

Sonax makes two varieties, one of which works faster than the other. It's worth the extra few bucks for the faster stuff.

For best results, after spraying down the wheels with Sonax, I will take a soft brush and agitate the surface a little bit before rinsing. The wheels will "bleed" as the brake dust and other deposits are pulled off of the surface. It's fantastic stuff. I usually spray the wheels, then quickly spray/rinse the engine bay (with a different product), then rinse wheels.

Yeah I bought the fancier sonax. It's 30% more concentrated, or something like that.

I don't use it on wheels that are mounted on the car. Much easier for me with them loose.

I don't have my wheels off often enough, but yes, it's easier to clean wheels when they're detached. Especially the barrels, when your wheels have a bunch of thin spokes like the OEMs on mine. That said, it works fine with the wheels mounted. There are a few products at Autozone/Advance Auto that must use a similar chemical as Sonax, but they're both less effective and less kind to the finish...my truck's wheels are a testament to the latter part. :(

If you do take the wheels off to clean them, Sonax also sells some kind of wheel finish protectant in a rattle can. Can't remember what it's called. I got a can for free with one of my more generous detailing purchases, and it seems to make wheel cleaning a little easier/faster. You have to thoroughly clean and dry the wheels before applying, however, and you definitely need to have them off of the car.