I checked my spare today and was surpised to find that it was at 50PSI. After I took delivery in mid June, I set it to 65 PSI (I always set my spare higher, it is far easier to bleed it down to spec road side, then to pump it up). Losing 15 PSI in 3.5 months is a lot, even factoring in the 20 degree cooler temperature. Check yours. The worst time to find out your spare is low, is when you need to use it. I set mine to 70PSI and put it back in the hole.