Updated: May 19, 2019
It's actually a myth that silicon based tire dressings are what turn tires brown. Silicone is sticky, so it may allow dirt and dust to hold on to the surface of the tire as you drive, which yes may turn the sidewalls. In this case, you can remove the color with a simple clean, using a brush and some water. Likewise, you can also remove silicone-based dressings with special degreasers and scrubbing.
The real cause of why tires turn brown is a process called "blooming" This blooming, or tire browning, occurs mainly because of an element added to the rubber called antiozonant. It saves tires from premature drying and cracking due to the process of oxidation. It’s a continuing process that can be prevented by thoroughly cleaning and protecting the tires.
Why Antiozonant Causes Tire Sidewalls to Turn Brown
Tires bloom because antiozonant pushes its way to the outer edge of the rubber casing with time. As the element comes into contact with oxygen, it leaves a brown residue on the surface of the tire. Antiozonant is organic and helps tires last longer as it slows deterioration due to oxidation. This is what makes it possible to manufacture long-lasting high-mileage tires.
The rubber structure is built in a way that allows the element to move forward to the surface, thus continuingly providing the material with its benefits. As a result, the tire remains pliable and UV/oxygen-resistant for a longer time.
Mold Releases as Contributors to Tire Blooming
Mold releases used in tire manufacture don’t make tire sidewalls turn brown. However, they contribute to the issue as they keep antioznant on the surface of the tire. Moreover, the more of it is left near the outer edge of the tire structure, the more the oxidation process will make it leave brown residue.
Mold releases are non-stick lubricants put in tire molds. They help release ready tires from the forms freely. Some of the lubricant usually remains on the tire, so it may contribute to blooming after just a couple of weeks of driving.
Importance of Regular Tire Cleaning and Dressing
Tire sidewalls turn brown continuously, so you won’t get rid of it completely. However, cleaning and protecting will prevent tire blooming or take it away temporarily if it’s already there. Clean your tires every time you wash your vehicle
Every tire has its own predisposition to blooming. This depends on the rubber blend, the type of tire how and where you drive, etc. However, regular cleaning and protecting procedures will help you prolong the tires’ life and avoid blooming.
There are several methods to cleaning tires. Regular cleaning with your left over car wash soap and a tire cleaning brush should be sufficient. However if you wash your vehicle infrequently or already have badly browned tires a rubber cleaning product will provide better cleaning than just car wash soap.