We use the SmarTire system where the sensors are installed inside the tire, banded to the rim. I think we get reasonably accurate pressure and temperature readings that way. In general, we see a 10-12 PSI increase in pressure and a larger increase in temperature, which seems heavily influenced by ambient air temperature and sun exposure. We'll run temperatures of 125-135 up to 80 degrees ambient. One tire maxed out at 156F for a short while on I-20 in Alabama on the sunny side of the coach with ambient temps right around 100F.
The other thing we've noticed is that the inner duals will run slightly warmer than the outer.
George C.