I'll test this myself, but asking here in case anyone has already done it. I have a new set of GM TPMS sensors (13581559) for a set of new wheels. The TPMS valve stem nut is coming via 4 TPMS service kits that include the nut and were >$2 each vs $5 for just the nut from GM. The next step is to install the TPMS sensors on the wheels and then drop the wheels off at the tire shop for the tire mount/balance. I'm wondering if I can test the new TPMS sensor before a tire is installed. i.e. will the trigger tool work and the sensor begin transmitting if the sensors are at ambient pressure? I expect they will. Has anyone tried this?