I understand pyrometers for measuring temperature. However, if you are out and able to point a pyrometer, you should be able to use an air pressure gauge.
I can see using a pyrometer to tell temps on a travel trailer to help diagnose an alignment issue, stuck brake, or wheel bearing issue, when pressure are still in the ok range. I just don't see it as a substitute for an air pressure gauge.
If checking the tire pressure is difficult for you, then really you want to invest in a TPMS system. Even if you are good about walk around inspections...and you should be, a tpms is a really good item to have, as it can warn you when you have dynamic issues, like puncture that you wouldn't notice until your next stop.
