What about substituting the airline dryer/antifreeze? We know that stuff will not hurt the airlines or CTIS system right? It is also cheap. I have no idea what it would do to rubber but given that there are rubber O rings and diaphragms all throughout the system and given how very, very tough tire rubber is I bet it would work. Weren't some of these trucks equipped with a tank that you filled to automatically blow it thought the air system? I don't think regular antifreeze has any real sort of drying components, not when it is cut with water at 50% anyway. I bet it would help lubricate and keep valves free. My point of concern is the air dryer. I have no idea what would happen to that. I don't have CTIS but as I understand it it adds and vents pressure from the tires as needed. At no point does used tire air get recycled into the main system right? The tires must vent from near the hub so it isn't like you could drain the tire while airing down. I bet you blast a little bit out each time however, few drops or so. The air from the tires isn't passing through the dryer, but does it vent into the intake stack like my air system does? That could be an issue. Again I don't have CTIS so for me all this speculation is academic but I have sort of talked myself into thinking it would work fine, maybe even keep the system working better with the lubrication. I would want to know where it vents, where that air goes and how expensive the 'down stream' parts are incase they pack up because of this. All the parts of the system are build to handle some moisture, you are talking about replacing corrosive moisture with moisture that protects against corrosion and freezing. I am starting to think that not only will it not hurt the system it might help.
On a side note, I was contacted through youtube by a Desert Storm maintenance guy saying that they used to pour a bunch of antifreeze in the tires whenever they changed one. (sounded like they did it on the sly) I did not ask if they were CTIS trucks but for that war it could have been either/or. He said they did it for heat, to keep the tires cool. Someone I spoke to on SS mentioned the same cooling properties.
-Ken