I also use the Doran TPMS. I always set the tire pressures using a good quality digital tire pressure gauge.
This is the one I chose. Amazon.com: Accutire MS-5515B Truck and RV Digital Tire Gauge with LED Light and Bleed Button: Automotive
The TPMS sensors & monitor are generally close but not perfectly exact. I trust the digital gauge totally versus the TPMS.
The TPMS is there to alert me to unexpected changes in tire pressures not to report exact pressures.
I use an IR temperature gun to measure both sidewall temps near the tread and also hub temps checking for bearings. The sunny side will ALWAYS be hotter than the shady side. You only look for something that is WAY different than the others on the same side. For those systems with external sensors that measure tire temperature, the temperature at the sensor will seldom be the actual tire temperature. After all, how can it be with the sensor out on the end of the valve stem!! An IR gun will give you closer tire temperature readings providing that you take the reading of the sidewall near the top where the tread is attached.
Just my opinions.
Dr4Film ----- Richard