Originally Posted by TiStick
Like suss6052 said, it should show when one is lower then the rest, or when they all are under a certain threshold.
We drove for years w/o TPMS, and it really wasn't created to help us, it was put in to keep lawyers employed.
There definitely is no substitute for the reliability of checking them yourself, but having for instance one front tire 14 pounds less than the other will cause some messed up handling. Yet no light to inform you. If they installed these things for our safety, the margin of error shouldn't be so large.