I have the tire pressure monitoring system and it seems that the computer measure is always about 7psi lower than a manual measure... which is right? i am not sure which one to use, i use the manual measure... thanks...

 

You can use the computer and reset and relearn the pressures, but it's pretty inaccurate regardless. The only thing it is good for is telling you that you have a flat before you drive off.

 

I would always go with the manual measurement. My TPMS also reads around 4 psi lower, and gives me pressure warnings when not required. So by always crying wolf, I wouldn't likely catch a major issue until too late, unless I happened to have the right display in view on the speedo.