The aluminum wheels were clear coated several times to protect the metal finish. Some excessive coating can leave the wheel nuts an excessive distance from the wheel hub when tightened, allowing them to loosen over time.
Dealers will remove the clear plastic coating from the brake rotor mating surface on the back of each wheel and from the wheel nut mating surfaces. The wheels will be reinstalled and the wheel nuts tightened. Wheels, hub bolts, and nuts will be replaced if necessary.