Current TPMS design allows the sensors to go to sleep when not in use to preserve battery life. Since the spare tire never rotates while in storage, the TPMS sensor would never wake up in order to provide a signal to the system.

I would be more concerned with the ability of the OE lug nut wrench to fit on the OE swollen lug nuts. It didn't on my F150. I have aftermarket lug nuts, and a real 6-point deep socket with long handle ratchet wrench in my on-board tool box.

 

We put a man on the moon with analog technology and still get signals from both Voyager spacecraft. Surely they can figure out a way to make that work.

 

Sure they can. Its bean counters and high priced management that determines stuff like that, not engineers and designers.

 

First they need to give us the same tire and rim as a spare!

 

The spare tire sensor would wake up and report if the spare lost several pounds of pressure in a short time, or went below a certain pressure threshold, just as the other sensors do. I had a Grand Cherokee with TPMS in all 5 tires (the spare was on a regular wheel and was in rotation). The spare did not usually show up on the display, but it would alert if the pressure in the spare got too low.

 

I lower and check it once or twice a year and fill it to the max pressure on the sidewall. If I use it, I'd rather need to let some air out than add some.