Depending on what year your Nitro is, it probably has sensors mounted in the rim, the outter part that you can see with the tire on being the valve stem. Under that, inside the rim, is the main sensor/sending device, that transmits a signal to the BCM (Body Control Module) in your car.
Some earlier models instead used sensors which were held in place by a metal band, in the center valley of the rim. And there were even some systems that used the cars ABS (Anti-Lock Brakes) system to deduce if tire pressure is low. The latter system has been regulated out of existence for use since 2008 models, and the former system has been mostly replaced with the valve stem type, because it's cheaper and works better.
So basically, if either of you want the TPMS to work, you have to have a compatible sensor mounted in the rims, as well as the technology inside the car that reads them. The buyer may want to keep the original sensors in his old rims if he plans on swapping them from season to season. That way, it's a lot less work/money.
And if you want your TPMS to work, you're either going to have to keep your old sensors, or get some new ones. Depending on what kind of rims you're getting, your original ones might not even fit. Like if your original wheels were steel, and the new ones are Aluminum, they will be thicker where the valve stem goes.
