Prior to installing the FOBO TPMS on my front tires I checked the pressure with my fancy, expensive digital pressure gauge and it read 19 PSI. This seemed good but when I installed the FOBO’s it read 17 PSI on both tires Thought there might be a misread from the FOBO so I tried my analog pressure gauge and sure enough it read 17 PSI. Looks like I have be running under by about two pounds for the past months. I’m sold on these tire pressure monitors.