If it wasn't included, go back to the dealer. While you're there, have them go over your features.
Mine was 38.5 all the way around. And I was expecting it to be below spec to make the ride more cushy. I thought I'd have to add air and had my compressor all charged.That also gives you a clue that the pre-sale check was not done properly.
Check your tires' PSI. They could be still 40PSI+.
Automaker pumps 40+PSI to the tires when the cars go out of factory so that the tires do not develop flat spots while sitting on boats, storage grounds, parking lots waiting for the new owners.... just FYI.
If it wasn't included, go back to the dealer. While you're there, have them go over your features.