As stated above WESTLEY'S WHITEWAL BLEACH will clean them up like new. May take a few times but it will bring the color back out.
I had the same thing happen on my old Chevy. I used brake fluid to shine them up, and a couple weeks later, they turned brown. This was right about the time No Touch came out, and the stuff did the job. It is the only spray on cleaner I have used that actually cleans.
I use Simple Green. I spray it on straight ans it pulls the brown crap right out of the rubber. Sent via Western Union Express.
So now not even a 49' Ford with bias plies is acceptable ?? I think some of you are taking this traditional hot rod stuff WAY too far. It is ok to talk about Marvel Mystery Oil, Cal Worthington, and a fiberglass bodied Uncertain T, but not this ?? Very confusing. Don
I think some are over policing the forums...seems like the OP asked a question that could affect anyone here...and obviously has by the number of informative replies.
Useless, dumb replies near the beginning. Helpful ideas, answers and advice after that. I have new 16" BFG Long Miler tires from Coker that are doing the same thing, not as pronounced. They are kept inside and have 0 miles on them. Bleche Wite (looks like they were bought out by Black Magic) sure works good! I haven't used it on the above mentioned tires, but on others it had done marvels!