beating a dead horse about tires, but have a question

I have my alarms on the TST507 system we use on the truck and 5th wheel set at ~10% below and ~20% above cold inflation pressures for the trailer - perhaps a bit less on the high pressure alarm for the truck as it doesn't experience the pressure increase when hot that the trailer does.

That's probably a pretty good starting point - you may find that you have to adjust them slightly based on the unique operating characteristics of your rig.

Rusty