I just had my tires rotated and the tech added a few lbs of pressure, to 50, as measured by his digianl inline gauge (at Firestone). TPMS shows 48, so not too bad.I posted on another thread about the new vehicle status app displaying tire pressure about 4-5 psi low compared with a good quality tire gauge. It's going to become a problem for those of us in climates that are going to be getting colder soon. Should be an easy fix with the next software upgrade.
But here's the rub, three cheap analog gauges (2 of the simple pen style slide-out ones, and one that is part of the filling assembly on my air compressor) all agree at one number, the 4 TPMS sensors all agree at a different number 5psi different...Creating a device to respond to relative gas pressures is not, as it's fun to say in these forums, rocket science. As such, if one has three or even two pressure gauges that agree with each other, there is an excellent chance they are correct.
So I check the widget regularly. I will say that the tires don't seem to lose pressure except when the temp changes significantly. I expected that they would.