Gordy M

In our area we are fortunate to have Danny Kellermeyer and his shop available. He has a scientific pressure gauge he uses when teaching performance handling on Corvettes. He uses a 4" Longacre gauge at the track, I believe, and measures it every year against his scientific gauge. He notes the difference every years on the variation and when he races he recheck the tire pressures to the corrected pressures he prefer's. The last session I attended there were about14 of us at his shop and everyone had a different gauge reading at 35 lbs. It did not matter if you and a neighbor had the same gauge or not, every ones readings were different.

BigTim

Use what your comfortable with. There will be variances in anything mechanical. And really....does half a pound really mean anything to a daily driver? If yes that’s just OCD get over it.

romandian

you can get a cheap one and calibrate it against an industrial manometer (5% accuracy). and dont check the pressure at a gas station. i have seen as much as 5 psi off.