I have read many posts about browning seen on tires. It is supposedly an expected event as a tire ages and some tires are worse than others depending on the compounds in the casing. I was wondering whether how a tire dressing affects it or is some of the browning.

For example, after you dress a tire, the dressing erodes away over time so obviously so something is left on the tire over time after the optical (a dressed tire) effect is essentially gone. So, is some of the "brown" on the tire just residue tire dressing?