I agree with exps01’s response above, our 310RL is listed at 110 psi, I just checked pressure yesterday.
The psi listed would be reflective of the GVWR from memory @ 15000 lbs.
As an added comment, I would think that if you had a full weigh done and were able to determine actual position weights for each tire and found the values less than the max values listed, you could research a brand specific inflation vs weight chart and set it according to the manufacturer recommendation.
Personally, I wouldn’t get my hopes up that you might be able to reduce pressure, our rigs are heavy.
Just wanted to be sure you had fully context in reference to your inflation question.
Travel safe!