I normally used BRILLO PADS and warm water.
Another product is WESTLEYS BLEACHE WHITE.
Be careful with the BLEACHE WHITE...it can cause spots on the wheels or hubcaps that are hard to get off.
But I always preferred the BRILLO pads, even if it was a little more work.
The whitewalls will come out SNOW WHITE again.
If you do get spots on the wheels, what do you recommend to remove them??