Tire Browning: Blooming
Modern rubber formulas used by tire manufactures contain an ingredient called Antiozonant. An antiozonant is a chemical that tire manufacturers add to the tire rubber to help prevent rubber degradation (cracking, splitting, oxidizing, and overall deterioration) due to the rubber’s interaction with ozone (an odorless gas that is part of the air we breathe). Quite interesting is the fact that tire rubber is designed to constantly work the antiozonant to the outside of the tire as it rolls – in this way, the outside surface of the tire is continually replenished with fresh antiozonant. This process provides the positive result of ozone protection, but the negative result of tire browning – once the antiozonant gets exposed to the ozone in the air, it turns brown due to oxidation. The technical term for this effect is blooming. The next time you are in a parking lot, observe the tires on the vehicles you pass – most likely you will see a brownish film on the surface of the tires.
As we will discuss in a moment, you can wash your tires with car wash soap or an all-purpose cleaner (APC), e.g. Purple Power Cleaner Degreaser, to remove some of the film, but it will simply return in a few weeks!
Every time you drive your car, the antiozonant migrates its way to the outside of the tires. One thing you might be aware of is the fact that vehicles that sit for extended periods of time (months or years) often have tires that show evidence of cracking and drying (dry rot). This cracking occurs due to the fact that there is no opportunity for the tires’ antiozonant to migrate to the surface to provide protection.
