First it does not say MAX 80 PSI Cold... It says Maximum Load XXXX at max pressure of 80 PSI cold (Cold is about 72 degrees but do nto sweat that too much) and that means what it says.. 80 PSI at any temp you are likely to be checking the pressure at first thing in the AM after at least 8 hours of PARKED.
What the pressure is when going down the highway (USE a remote reading TPMS to check at 55 MPH) Well note the pressure on all tires.. if ONE is way higher than the rest you have a problem (likely a dragging brake or a bad bearing in that order) but else do not worry.
Likewise if one is LOWER than the rest (Leak).