We run our tire pressure according to the label behind the drivers seat. We tried maximum pressure on the tire and in between. it near beat us to death and loosened things up.
Now different tires than factory installed, like Michelins replacing GY670s might need a bit more pressure since they have more flexible sidewalls.
We watch tire temps, with heat gun. I'm not sure what the pressures are now. Where we store adjsuts them according to a table. Most of our coaches do not weigh anywhere near what a semi does and except for the Goodyear and Michelin they all are more or less semi tires and rock hard at max pressures.
Follow the coach manufacturer's label even if you add a thousand pounds of cargo. tires get warmish add five lbs.