We were camping with family last summer, it was very hot, windy and miserable outside in heat of the day. I told my BIL that I had a cover that I had found that I would give him to cover his spare tire. It was many years old and looked brand new still mounted to the back of his trailer. I was sitting outside after it cooled down some and looked over at this spare, it looked odd so we went and had a look. The tread had split a third of the way around the tire. It was rotten for sure. His awning was the same age and a gust of wind ripped that off too. All in all we had a good trip, him not so much. He did replace spare and I gave him the cover I promised.
Replace the spare..