Thanks again, all. I found Simple Green okay. Being a member of BTM (Black Tires Matter) I figured there was something better.
My tires had that brown stuff on them.
I wanted to do before and after but the camera in my phone is ca putt. You'll just have to take my word for it. This stuff is the tits.
Not affiliated in any way.
Amazon search, Adams Polishes.. Tire and Rubber Cleaner.