[RMcNeal]

I have sensors on both the truck and the trailer, including both spares. My '14 F350 has TPMS, but it doesn't tell me anything about what PSI or even which tire it is if there is low pressure. It just says "low pressure" and then flashes the tire icon. Also AFAIK, the built in TPMS's don't give you temperature readings or thresholds.
I included the spares so I don't have to climb under the truck and trailer to periodically check them. Just peace of mind, I guess.