G'day John,
I too have a troublke keeping my Whitewalls clean, and the best I have found is Brakleen.
What I do is spray the Brakleen on a rag and immediately wipe it only on the white part of the tyre. But, don't get it on any paintwork.
I find that the rag must be constantly changed as once it is dirty, it doesn't clean as well. But, it doesn't take long to wipe aroung the circumference of the whitewall.
Bruce,
The Tassie Devil(le),
'60 CDV