RAM 1500 Owner's Manual page 556

554 STARTING AND OPERATING
The matching full size spare wheel and tire assembly (if
equipped) has a TPM sensor. The full size spare can be
used in place of any of the four road tires. A spare with a
pressure below the low-pressure limit will not cause the
"Tire Pressure Monitoring Telltale Light" to illuminate or
the chime to sound.
Tire Pressure Monitoring Low Pressure Warnings
The "Tire Pressure Monitoring Telltale Light" will
illuminate in the instrument cluster and a chime
will sound when tire pressure is low in one or
more of the four active road tires. In addition, the EVIC
will display a "LOW TIRE PRESSURE" message for a
minimum of five seconds and a graphic showing the
pressure values of each tire with the low tire pressure
values flashing.