You set your cold tyre pressure on existing temperature. The real temperature of tyres will change about 0,1 bar/10 celsius. So if you set tyre pressure when outside temperature is +20 celsius (cold tyres) the real temperature of tyres is 0,2 celsius lower when outside temperature is 0 (zero) celsius in the morning. I think that the pressure warning is alarming when tyre pressure is decreased about 0,3-0,4 celsius of adjusted temperature. If you dont`t want any false alarms, you have to be careful that every tyre is at the same temperature when you set your TPMS-system. If one tyre is in the sun and the other in the shadow there may be more than 0,2-0,4 diffenrence in the real pressure.
Uti