The PSI number on the tire sidewall
IS NOT A RECOMMENDATION. It's the amount of cold inflation pressure for that tire to provide its maximum load capacity.
The OP has "plus sized" his tires to an extreme. The proper procedure for those replacement tires is to get a load inflation chart for them, find the vehicle manufacturer's recommendation for the OE tires and establish a new recommended cold inflation pressure that is equal to or greater than what the OE tires provided. Anything above it, all the way to tire sidewall max is considered optional.
https://fifthwheelst.com/documents/C...T-Modified.pdf