I looked but didn’t see any info on this subject. I was told having a tire hanging in the backyard can make a pit aggressive. Before I tried this, I was taking down a branch off the tree in the yard and my 1 year old male pit ran and jumped for it. So I thought he might enjoy a tire. We hung one and he loves it. He’s not aggressive when playing with it and provides a good hour or so every day of mental and physical stimulation. He’s also not aggressive when the other dogs go near it so I think it’s ok but would love some input before I hang a higher one for him.