[Tom Goldman]

One of the best is the Moroso 89552 gauge which is 1/2 % accuracy.
Unfortunately ,it's not the easiest to use since you need to keep it protected in it's case and it must be held upright .
That said, I use it to check and calibrate the 89592 0-15 # gauge I normally use. I check it at every race .
Most common gauges are a 2 % accuracy type ,which means a typical Stocker with 20 # of tire pressure in the Radial slick can be off plus or minus nearly 1/2 # .
Digitals can be ok and they certainly will survive the abuse they see laying on the floor in many cars, most are still 2% accuracy ,they still should be checked regularly . ......One bad thing about digitals is that when left in the heat of the car or direct sunlite the LCD display can become un readable .