I found the tire pressure indicator to be calibration to be slightly off compared to my digital meter (probably about 0.5 PSI) and a standard pop-up manometer I keep in my toolbox. The metric (kPa) unit of measure is a bit more granular than the PSI scale. The 'rounding' function may be causing some variance too, particularly with respect to the PSI scale, so I stick with the metric display setting on the DIC for accuracy.
Check and fill your tires in the morning prior to driving the vehicle (i.e. "cold"). The tire pressure will rise even after driving only a short distance of mile (1.6KM) or less. Ambient air temperature has an effect on tire pressure. Likewise if your vehicle is in the sun, the heat induced by the sun hitting your tires will cause a difference in tire pressure from the tires that are otherwise shaded from the sun. Obtaining consistent results can be a bit of a challenge!
Having several tire pressure gauges calibrated the same is much like that of trying to synchronize several different clocks. Which one is right?!? Getting the tire pressure (within reason) to the manufacturers recommended setting doesn't have to be perfect science. So long as you're checking and setting tire pressure regularly with a proper functioning tire pressure guage, you'll get optimal ride quality and tread wear. <Don't forget to rotate your tires, that's also key to good tread wear.>
Regards,
/BTV
