It’s really hard to tell when a run-flat tire loses air, as it’s designed to work without any pressure inside (for short periods of time). For that reason, every car that comes with run-flat tires from the factory also has a TPMS (Tire Pressure Monitoring System), which can signal the driver if one of the tires loses pressure.
Thus, if you want to put run-flat tires on a car that didn’t have ones before, make sure you also have a TPMS. If not, the run-flat tires could actually be detrimental to safety, as you won’t know when they lose pressure.