Tire Swings (are these still safe)

Everytime we go to visit my parents, the first thing the kids want to do is have someone push them on the swings. I secretly hope each time that they won't remember because I know that I am going to have to stand out side and give each of them multiple turns on the huge tire swings. These swings have been in our back yard ever since I can remember. Everytime the kids swing on these I wonder if these are still safe since they are so old. While we were watching Grandpa swing the kids, my mom reminded me of the time I decided to take the family dog (mittens) for a ride in the swing. I had forgotten about the incident but soon remembered the horrible experience. I don't remember how old I was exactly but I was pretty young. I thought the dog would love to go for a ride in the tire swing with me. I was so proud that mittens was sitting in my lap and not trying to jump out of the swing while we were swaying back and forth. Before I knew it, Mittens was starting to dry heave. I wasn't sure what she was doing but before I could stop swinging she projectiled pink vomit all over my lap. Needless to say, that was the last time I ever took Mittens for a ride in the tire swing.