[T77911S]

I have 2 sets of CIS gauges, both purchased at the same time (they sent me 2 by mistake and told me to keep it). at higher pressures they DO NOT measure the same psi.

I have thought about the same with a tire pressure gauge since I just bought a nice one to go racing with.

I figure its all relative. that is, if you determine 20psi is what you need for cold pressure, then as long as you ONLY use that gauge, you will never know or care if it is accurate or not. you just need it to be consistent.