New Tires

My belief is that since the spare usually but not always is kept out of direct sunlight it should be good enough to continue being a spare for a while. My trailers have all had the spare underneath the frame and on the rare occasion that I needed to use or inspect it I found no cracks or obvious signs of deterioration. Age of the tire figures into the equation because after around 6 years they are not supposed to be used as a permanent tire. As with everything in our world right now tires are very expensive and buying 5 just to put one underneath as a spare is wasteful. But it depends on your financial situation and peace of mind. All of my spares on my RV and both boats are older tires that I have either pulled out of service or they came with the unit when new and I never replaced. I do however once a year check for dry rot and obvious knots or bulges or signs of separation. Keeping the lug nuts checked for proper tightness is more important than keeping new rubber as a spare!!