White letter problem with bf goodrich tires

pishta said
The white is molded into the tire as white rubber, if the oils are seeping through from the back, how does cleaning or sanding the surface help? If only the tops are staining, the oils in the tread cap are in fact leaching into the white casing...

I don't know, but it did work, and they stayed white for a few months. I got rid of them however, replaced by red-line tires by Diamondback.