Trailer tires are a serious risk, but motor coach tires are every bit as dangerous, maybe worse. The motor coaches need them changed every six or seven years and the more they sit the shorter the life. My rig with 295 75 22.5 tires sees maybe 50,000 miles in that time. Funny thing is, over the road rigs get 300,000 miles or more because the tires are in use. Sitting causes the metal cords to separate from the rubber and that is bad.

Keep them at maximum recommended pressure. I'm not sure if ultraviolet deteriorates the rubber or not. My understanding is that ozone is the real culprit. 02 will oxidize anything, even people, which is partly why we also age.

Loren