Virtually all alloy wheels are painted and/or clear coated. When you add wheel-balancing weights that clip on and scratch the paint, it can let corrosive moisture and other substances get to the underlining aluminum. The same goes for any scratch marks made from careless handling during tire rotation or damage caused by road debris or curbside parking.
Once pitting has gotten in, you will need to protect your wheels and eventually have those wheels refinished. Don’t take the chance of causing further damage to your wheels bring it to a professional to ensure proper installation.
To protect your wheels during the winter months, apply a generous layer of wax to the wheel which will help repel water and other corrosive materials. Also check with the car wash attendant before you take your car through a car wash as some use acid cleaners before or during the wash to remove dirt and grime. Others may use stiff brushes for cleaning wheels and tires. Both of these processes can harm your wheel finish.