Difficult wheel cleaning

[Lori's 2002]

I have used only Adams products since I first met him at the OC swap meet in ca 20+ years ago. I love the products and the forum has been my “I’m stuck” go to for years, but now I am totally stuck and it seems like something simple but it’s fighting with me! I’m cleaning the rim in back behind a deep wheel. Usually my go to is Tire and Wheel, that didn’t touch it. Neither did these: wheel cleaner, all purpose, eco, I even tried good old dish soap. No matter what I use it looks ok while wet but then drys and is back to looking like brown dried on brake dust. It doesn’t even budge with the rubber handle end of a brush. The rims themselves clean up great but the wheel looks awful with this visible between the spokes : ( 

Any ideas? 

[BrianT]

Does a clay bar remove it?

[Lori's 2002]

I’ll be working on one of their other cars next week, I’ll give the clay bar a try. Thanks for the idea, hope it works.