42psi - they pick such things more often than we would like
I had a chance to go with them a couple of times, and was really surprised how they can spot little things while going so fast, talking on the radio and making sure they don't bust their clearance. So fortunately, we can usually perform a runway check in one, maximum two gaps. We also came to agreement with them which makes them announce their check intentions on the radio and asking which runway we'd prefer first and from which direction. They are also very accomodating and if needed will wait, unless there's some really important reason to check the rwy immediately.