Oh my God!
Does anyone actually know the chemical composition of a modern tire and it's side walls?
The manufacturers puts anti-UV waxes in the rubber, there is carbon black for heat absorpsion, etc.
Oily silicone dressing do provide a "getto shine" to a tire, but as all the major tire manufacturers state, "don't use them, they break down the side wall of the tire!" (some even put a disclaimer in their tire warranty regarding the use of such dressings)
That said, when you spray a "clorinated solvent" to the tire, you remove even faster these components and in time in time, a couple of things happen.
1. As soon as you do clean with brake cleaner, you do observe the "browning", which means that the carbon black and anti-UV protective waxes have been somewhat removed. (early side wall failure)
2. The removal of these components will normally cause the tire sidewall to exhibit a "brown" color.
It is not SAFE, it is not right, it is as wrong for the tire as using a "silcone fluid based dressing with a hydrocarbon solvent for it's carrier".
If the tire is as bad as to have a build up of the silicone, and you attempt or actually remove it, you are just taking off those important tire components as the silicone/dimethal did when they attacked the side wall by using a clorinated or highly active solvent.
A pro shop has to deal with this sort of issue and once out the door, out of mind.
However, for an individual's vehicle, don't do it.
Take your time, use a safe water borne cleaner (APC) and scub it, drive it and more of the dimethal silicone will migrate out of the sidewall, and you can clean it again.
After some time, it is gone and you still have some sidewall with what the tire manufacturer put there for a reason.
The flexing of the sidewall is meant to "migrate" the waxes and carbon black to the surface.
Every notice that after a long 100 mile or so run in hot weather that you see, no matter if you use a correct water based amino functional siloxane resin dressing, that the side wall may look shiney and be "tacky" to the touch?
That is the result of the heat flexing of the side wall, moving the anti-UV protective wax and carbon black to the outer layer of the side wall.
It is designed to do that!
When a vehicle sets, the sun hits it, it eats away these protective components, designed to do so.
Ever notice that RV's etc that set for a long time usually have covers on the tires?
The sun and it's UV's will eat away the protective components since the RV is not being driven, creating the flexing and migration from inside the sidewall to the surface, so they have learned to keep the UV's away from the tires.
Long winded and I could go on, but just read and "think" before taking an action that may end up costing you a lot of money and compromise your safety.
Grumpy