Well this interesting, I took some paper towels and vinegar out to the car and I was surprised to find it removed about half of the grime but after doing around 1/3 of the wheel I started to wonder this was the best thing to use so I went and got a can of cheap leather/vinyl protectant I use on my furniture. I applied it with a clean rag and found with a little work it removed all but perhaps %10 of the remaining grime. Did the entire wheel with this "protectant" and stopped with the vinegar. Right now the whole wheel is a little sticky but we'll see how that goes. Funny how dish detergent and some vinyl cleaner made by prestone didn't work anywhere near as well.
I noticed the cheap leather/vinyl protectant says "cleans, conditions and protects" in small print. Made by AutoBright. Bought it at some discount store a couple of years ago. I may go back and see if still have some.