In the old days, we washed the car and used the same soapy water and a brush to clean the whitewalls. They came out nice and bright. However, today’s whitewalls seem to turn beige after a few weeks and the auto parts stores' shelves are filled with special sprays and nostrums to clean whitewalls. Many of these products work, but leave a cloudy film on the body of the tire or cause it to lose its soft sheen.
This is a companion discussion topic for the original entry at https://www.hagerty.com/articles-videos/articles/2006/05/30/whitewall-preservation