As has been noted some of these systems work without wireless transmission - by measuring minute differences in tyre rotation speed.
Some work by sending a warning only when the tyre pressure falls below a certain level (28psi generally).
Even the high-end devices that transmit the exact tyre pressure to a central console will not be transmitting continually - smart ones will only transmit either when the pressure changes, or at a fixed polling interval.
So triggering an IED when a particular car drives past ? Not likely - only if you are unlucky enough for one of the sensors to be transmitting at the exact time the car drives past.
Same goes for monitoring movement of an individual car - the chances of the pressure sensor transmitting at the exact time it drives over/past a sensor is pretty remote.