I'm a Dr. Beasley's authorized detailer. I am also a person who likes to "pressure test" products to see how they perform beyond what a recommended usage should be to discover how good they truly are. I disregarded the instructions of rinsing the wheel first on my friend's Subaru WRX STI to rid his wheels of brake dust. I simply sprayed the product on and let it dwell -- dirt, debris, brake dust, and all. The best part of this product is that it does not have the toxic smell of traditional iron/brake dust removers. In fact, it hardly smells at all. The other nice thing is that the product has a gel-like consistency which allows it to stay in place to work rather than run down the wheel. This product IS NOT a color-changing brake dust remover. Do not expect the traditional purple or red staining to show the product working. After letting the product dwell for about 5 minutes, my friend used a wheel brush, and wheel wooly to agitate the wheels with soap. The result was a sparkling clean wheel/rim. Fantastic product that works very well and doesn't stink. If you have not yet, give this product a serious try.