An old thread ,but I thought my input might be relevant …
Most instrumentation gauges and institution specs have different accuracy ratings ….
En , asme specs are often quoted , but at what class ?
Also bear in mind percent accuracy is most often quoted at percent of range .
Range being the zero and span it is designed to read .
So ….. a 200psi gauge with an accuracy of 1% allows +\- 2psi
Whereas a 50psi guage with an accuracy of 3% allows +\- 1.5psi .
For normal car tires the latter would be more accurate ….
Normal operating pressure around half-range is the norm , but for more resolution span just over normal operating pressure may be desired .
It is also worth bearing in mind that a higher quality gauge will have much better repeatability and be less prone to drififing with age .
Likewise , a gauge with a larger face will be more accurate .
Another aspect to consider is most instruments come with a factory calibration when situated at vertical .
An instrument installed horizontal will show different readings from 100% calibrated vertical , but a quality instrument should still pass cal-check even if not adjusted .
Less quality instruments can have a large variance between vertical calibration and horizontal calibration .
Wheels constantly rotating move not from 0-90 , but 0-360-0 .
A quality installed tpms is worth much more than a badly made and used incorrectly pressure gauge .
Also worth considering is pressure increases with temperature , And vice Verca .
I can see a difference side-to-side depending on which side of the sun the car is parked on overnight/at work .
And a quality system/gauge will have enough resolution so that when you set pressures at cold temp , they track evenly as the tires get upto temp .
Last time I looked beruF1 had an ir array doing total width inner-skin temp as well as pressure .
Porsche cup cars now added temp as well as pressure , but I didn’t look if that’s temp at psi sensor or skin temp .
Analog , digital , bla bla bla .
Ask what nitc use to reference if it makes that much difference to your tire pressure gauge buying conundrums .
AND ….
I finished work about 5 hours ago , so back to drinking and wondering if I’ll get up in time for work again tommorow
