Tire Pressure - but wait... a different question!

I am amazed at how much some people fret over issues like this but use a gage they picked up for a couple of dollars somewhere. Most likely your gage is the largest source of error. I don't think it is even possible to get one calibrated but you should check your gage against two or three others to see if you get consistent readings. I have seen gages vary by 10PSI.