Do the tires stay green or just temporarily while the spray is on there? I know TarX has a neon dye for the purposes of using it on dark paint, the dye reacts when it is working. Wonder if that is what you are seeing on the tires...unless you are saying it leaves lasting green stain after you have wiped/rinsed it off?
My sister had an issue with tar on her Wrangler, so I brought her my TarX for her and her BF to use on it. I didn't have time to stay, so I told her to read the directions and gave her the link to the product and said good luck to them. (What a terrible brother I am

Anyways, she then texted me a picture of a spot on the tire being green and haven't been back to take a look at the tire again (this was Friday) or talk to her.
I have a set of tires in my basement and will see if I can make time to do some testing today and see what happens.