BF Goodrich radial T/A white letters

Wesley’s tire (bleach) white tire cleaner.
Old stuff works good.
Most manufacturers are no longer offering white letters or white out lined tires any longer.
What turns them brown… not keeping them clean I guess. Not sure if an owner thing or company thing. I’ve yet to see white walls, white lettering turn brown. My 9 year old cooper cobras are still white on my Demon. Cracked, but letters are still white. Enough armor all and you don’t even see the cracks. LOL!