Sounds like you could have a combination of braking matter (pad dust, metal particles from the discs) embedded in the paint / powder coat / lacquer on your wheels, so I’d try decontaminating them. Normally an iron fallout remover such as Car Pro Iron X or Valet Pro Dragon’s Breath (there are other similar products) will work and should be safe to use on all types of alloy wheel. These iron fallout removal products have a very unpleasant smell - to say they stink would be an understatement, so always use in a an open, well ventilated area.
Iron Fallout Removers Iron Fallout removers have grown rapidly in popularity over the past few years. These products are designed to remove iron fallout & brake dust from paintwork and wheels. Iron Fallout removers are pH neutral and designed specifically to react with the iron making them
www.cleanyourcar.co.uk
If a fallout removal product doesn’t work, then you could try using a clay bar. They come in different grades, but I’d always start with a light grade clay first and if that doesn’t work, move up to a medium grade. Always use plenty of lubrication (a quick detailer product) when using a clay bar to prevent marring to the finish on the wheel.
If you’ve also got road tar deposits on your wheels (I get this sometimes - little black spots), then a tar removal product such as Valet Pro Citrus Tar and Glue Remover should get rid of them.
I‘d avoid using harsh acid based wheel cleaners at all costs as they can damage the finish on alloy wheels, and if you’ve got black plastic covers on your wheel bolts, some of these acid based learners will turn the black plastic to grey or white.
Once you’ve removed the contamination, apply a couple of coats of protection - a sealant or wax with high durability - and re-apply it every 2-3 months. Avoid future build up of brake material by washing your wheels every 10-14 days. That way, with regular washing and topping up the protection will make it more difficult for contaminants to ‘stick’ to the surface of the wheels in future.
