I have used 4 or 5 different brands of whitewall/tire cleaner. Also a soft bristled brush and finally a Scotchbrite disc on a die grinder which is the only thing that worked. Within a couple seeks the letters were brown again. My Swinger was on our event t shirts this year and was going to be on display so I went to Fleet Farm and bought a couple new tires for the rear. (the fronts are a different size and have never discolored) I understand BFG has fixed the issue. We will see. If not at least I have a local dealer to go to for warranty. I didn't get that with Summit who I bought my first set from.