Underinflated tires on motor vehicles cause crashes due to tire blow-outs, immobilized vehicles, poor handling as well as hydroplaning. Accu-Pressure Safety Caps are a new tire pressure monitor product which will help drivers know when their tire pressure is too low. The chrome caps simply go over the tire’s valve stem and will display green when the tire pressure is adequate, yellow if approximately four pounds underinflated, and red when approximately ten pounds underinflated.