get some iron x on that wheel then seal them with some decent wax
that looks like brake dust and dirt contamination
iron x will take that off easy enough and f the wheels are sealed it shouldnt happen again really
i did our altea a few weeks back.


i also did my GTI bodywork a couple of weeks back and my car is bloody ridiculously clean and it still removed some fallout
iron x is really good stuff, especially as a wheel cleaner. it really stinks though


