Try Greased Lightening, very good cleaner and won't hurt aluminum, I have not tried it on whitewalls, don't have any.
Simple Green and a stiff bristle brush works good as well. But nothing beats Black Walls.
It's a chore keeping them clean, is there anything that can be used to make the task a little easier? Maybe a homemade concoction , I have tried purple power but it doesn't clean them as good as I want, even when using a scrub brush .