You cant really check the PSI in them with a gauge...You need a regulator and nitrogen tank...set the regulator and fill it until it doesnt sound like it wont take anymore air...this is only seconds of filling...the chamber is soo small that if you were to use a gauge, it would most likely let more out and your reading would be less and less each time. there is different theorys that the truck needs to be at full droop...but some guys say yes..and some no..i just do it yes...so that is up to you...If I only wanted to refill the nitrogen or check the psi in them do they need to be on the truck and at full droop?
yeah there is. but its much easier by just throwing em on the truck and testing...a way to calculate the resulting lift based on the change in the coilovers eye to eye length b/c this directly denotes how much lift youll have by compressing the coil.