Tires need to be changed every five years. They start getting sun rot if the coach is not used much on the road. If you use the coach at least once a month, it sure helps.
I just changed the air conditioner covers at ten years. The paint job on my coach still looks like the day I bought it ten years ago, so I guess I either got a good paint job or maybe the dry wash that I use helps keeping the paint in good condition. I use The Solution to wash my coach. I do not live in Arizona, but I do live in Barstow which gets up to 110 in the summer.