Although the picture is blurry, it looks as if the clear coat has separated and water/dirt has gotten between the metal and the clear layers. The wheels are painted silver and then clear coated. The aluminum is not deteriorating, but the paint has simply let loose over time. The only way to fix this is to sand down the affected areas really well, scuff up the rest of the wheel and repaint/clear the entire thing. Another option would be Plastidip. You'd still need to sand down the areas that were bad, but you could just do a few layers of whatever color Plastidip you wanted.