Our Concours Judge here in Chicago for the Chicago Region PCA (he also restores old 356's) recommends a 5:1 solution of Distilled Water to Wurth Citrus (
www.wurthusa.com) degreaser. Put the solution in a spray bottle to clean your wheels.
I have only used a wheel cleaner once (P21S) in the past 7,500 miles, and this was about 6,300 miles ago. I now wash my wheels with hot soapy water (Zaino Z7 Wash) and wax with Rejex. I have about 3 coats of Rejex on the wheels now.