D3721. Step 5.
The first few coats of paint have been applied. Each coat consists of a pass across the chassis to apply a very light coat of paint. This only results in a very slight discolouration of the wheels, or at least those parts of the wheels that show above the frames. The wheels are then turned a quarter of a turn using the battery and the exercise is repeated.
You can see in the accompanying picture that there is still one small area on each wheel that needs to be covered. You can also see that although there has been some overspray, it is only covering those areas that would be as dirty as the wheels. Notice also that the turning of the wheels while the paint is still wet has kept the pickup-wiped rear surfaces of the wheels clear of paint. No attempt has been made to keep paint off the wheel treads.