BF Goodrich radial T/A white letters

Good luck cleaning the browned letters with Acetone and Brillow pads. It doesn't work. If you can clean them with that, you don't have the brown letter issue we are talking about. The brown leeches in through the letters from the tire. It's not just stains on the surface. I ground mine with a 3M Scotchbrite disc in a die grinder. The letters came clean and browned a couple weeks later.