I appreciate your concerns; however, I really don't think it's necessary to fit one between the hook and tire. And, with the volume of air passing around a vehicle as you're traveling down the road, I'm really doubtful an environment will be created that would promote tire rot. In fact, I've read that some in prior model years were received with a cover for the spare. So, I'm interested in one myself and would like know where I can get one.