Also keep in mind that the TPMS can be inaccurate.
The temperature sensor , if on the outside does not measure the inside tire temperature , but something in the middle between in and outside.
Also the pressure can be inaccurate but I dont think at these low pressure thats the case here.
Dont asume , because if digital and it gives at 2 digits behind point, that its 100% acurate, the sensor determines the acuracy.
Then the inside tire temperature is only the air inside that is measured.
Sertain spots of the tire can have higher temperature at wich the proces starts that Tireman9 describes.
Then ST ( special trailer) tires are calculated in their maximum load for more deflection allowed, so if you use the pressures adviced you are closer to the damage border then an LT tire.
If the tire maker allows it you can put even 10 psi more then the "maximum " given in it so here probably 50+10=60 psi.
TRA allows it and describes it for higher speed and better handling.
But some tire makers dont allow higher anymore.
And you have to keep to all the laws, of country , tyre-maker, and nature.
