Tires are supposed to be black, so what’s happening when your tires turning a brownish color?
Tire blooming.
It’s the brown residue that stains the tire’s sidewall brown, caused by a tire additive, Antiozonant, that protects against ozone damage like tire cracking and dry-rot or ground-level ozone like smog.
The tradeoff is a brown residue on the sidewalls — Amplified when tires are sitting in the sun, exposed to the elements and not regularly going through their normal heating/cooling drive cycles.
And no amount of scrubbing or product can bring them back to black!
Manufacturers consider tire-blooming a cosmetic condition and most drivers don’t care what color their tires are! But if you like black tires, tire blooming is a problem!
Just like Weather Cracking and Dry Rot, most of the tires I see bloom are out of their warranty period, but you can slow tire browning by cleaning and protecting your tire’s rubber —
I use Adam’s Polishes Tire and Rubber Cleaner for tires because it’s citrus based and human-friendly, followed by a layer of Wizards Tire & Vinyl Shine which contains UV blocking agents to further help prevent your tires from browning.