Stained front rim

Has anyone with wire wheels have a front rim that is stained, looks like dirt but no amount of cleaning with multiple products will remove it. Found a blog in UK that said BMW dealers have been using some sort of cleaning fluid that has caused this and that BMW is replacing the wheels. Of course my local dealer says there is no such problem and has blamed me for using something that I should not have. My response is if that is the case why is rear wheel perfect since any cleaning product used was used on both wheels.

Most problems with wheel staining originate from brake dust left on wheels for excessive periods in wet or damp conditions. The metallic content of the dust leads to staining.Any pads containing sintered metal can cause it whether its copper or iron or something else.
This is a problem especially with painted rims and any aluminum that is not coated or anodized.
I coat my painted wheels with Keep Clean Wheel (a product available at most parts places which is chemically similar to a waterproof sunscreen without the UV absorbants and fills pores in paint). Any racer knows hard anodized aluminum is the easiest surface to keep clean for wheels but few street wheels are hard anodized (that's formation of an oxide that is hard, chemically inert and to which dust doesn't stick well)

There is a mixed version of this problem where an aggressive full strength cleaner is left on an aluminum wheel too long or in hot sun and it reacts with the dust already on the wheel to produce a permanent blotchy stain in the metal. I have seen this once. The resulting stains are indeed permanent and I know no way to remove them short of removing surface metal.

Most BMWs use organic compound rear brakes so there is no corrosive dust on rear wheel, only the front. Changing to an aftermarket sintered pad at the rear can improve rear brake performance but can add the possibility of staining at the rear

The problem will be lowest in the summer in most places because that's the driest time of year.

You may be able to remove it with those white sponge like cleaning pads from the supermarket- they contain a fine abrasive in addition to cleaner.

Bare, non anodized aluminum can be pretty reactive at places where its normal thin oxide layer is disturbed and inappropriate aggressive wheel cleaners meant for other metals like chromed wheels might well stain it- such cleaners can contain phosphoric acid and other stuff. General purpose wheel cleaners or those meant for aluminum won't.

I could tell you easily which if the above it is if I saw the stains. Might be able to do it from photos but no guarantee on that..

Personally, I suspect the wheel cleaner bit is wrong. At least in the US, wheel cleaners are clearly labeled about suitable and unsuitable use...

There are a few things like rust removers that someone might use near aluminum wheels that should not be allowed on aluminum but you would know if you did that..