Posted by Mike H on August 05, 1999 at 10:18:10:
In Reply to: new tires turning brown posted by Ellis on August 02, 1999 at 10:56:42:
Actually, it is not a contaminant at all. Rather it is a chemical that prevents deterioration by oxygen and ozone. This chemical turns brown instead of your tire cracking. Furthermore there is a thin wax film on your tire to protect it from oxygen and ozone in static conditions (i.e. when your car is parked in your garage). If you curb your tire, you will break this wax film and the oxygen and ozone will be in direct contact with your tire aggravating the discoloration.
In general, the blacker you tire stays, the more it will crack with time. In my opinion, I would rather have brown tires and drive them for 4 or 5 years than have tires that stay black and crack. Cracks are much uglier than brown in my opinion. Hope this helps.
Also since you have brown rings, I assumer you have a raised white letter tires.