Double Seal Tire Valve Stem Issue
We recently had a tire issue while on the road that was repaired by a truck tire company and involved replacing the tire valve stem. The technician replaced our valve stem with what I think is a double seal valve stem. When we got home, I added air to my preferred PSI and installed an external Tire Pressure Monitor. Several weeks later I notice the tire pressure is a little bit low, but when I remove the TPMS sensor I find that I am unable to get a reading with a manual pressure gauge (i.e. the gauge does not show anything) and my TPMS still shows a the slightly low reading...not that the sensor was removed. While I was driving around town, the sensor does fluctuate slightly.
I'm a bit stumped. Any thoughts on how I can check the pressure on this tire?