Interceptor tires brown, factory coated?

[MDX Detailing]

I did a 2015 ford explorer interceptor recently. Tires were very brown. I sprayed tuf shine tire cleaner, let it dwell, scrubbed, rinsed about 3 times. Tried again with purple power twice. Got a ton of gunk off but tires still had a brown hue to them. They were clean to the touch though. Upon close inspection the browning of the tire was a perfectly even brown, no blotchiness, and covered the entire wall of the tire except for a margin on the tread's edge. The margin was about half inch of perfectly clean black rubber, no brown. It looked to me like there was a factory tire coating applied by machine to the wall of tire and it had turned brown.

Anyone know if the tires of ford interceptors are coated from the factory? If not, what could this browning have been? There was no more dirt cleaning out of tire, foam from tire cleaner was a nice white foam!

[Mike Honcho]

A buddy of mine works down the street manufacturing Toyo tires, I asked him, and he said it is because of antiozonant being added to the tires to prevent cracking and dry rotting. What you are seeing is called blooming. It's the protectant added in the manufacturing process leaching out.

[MDX Detailing]

Blooming cleans off though. This was not blooming. The blooming cleaned off at the outer margin of the tire easily

[Don M]

I've noticed that some tires have different rubber compounds for the treads than they do the sidewalls and I've noticed what you have. There is a distinct line where the tire is (black) clean and where the tire is (brown) clean. You can even see it after the tire is dressed.

I don't think there's anything you can do except clean them the best you can, then dress them.

[MDX Detailing]

Different compound makes sense. That's what I did, Cleaned and dressed. Looked a ton better but was very frustrating. I think only a small percentage of people would notice the brown after dressed.