Last flat I had, was the first time I had the spare down since I bought the truck used. I called AAA since I was on a 4 lane that I didn't want to try and change it on and told them to bring air because it might be flat, it was low. When we got it down it turned out to be D rated and I had E on the truck and it didn't look great age wise. Instead of trying to find a replacement in a strange area I went to state roads and kept the speed down and limped home since I was only about 200 miles in to a weekend trip. I had two new tires put on the truck and put the good take off on as the spare. Now whenever I get new tires the best of the take offs go on as a spare, that makes sure the spare doesn't get to old.
Considering that is only the second time I have had a flat on the truck while on a trip in 40 years of hauling a camper around I don't consider having a perfect spare worth the cost, if I have a flat a long way from home I will find a tire store. In fact the first time I trusted the spare but didn't want to be without a spare for the rest of the trip so I stopped and bought a tire for a spare.
Jim...