ST Tire "Plies" Question and a PSI Question

Should the advice to be at full pressure despite the weight also go to LTs when mounted on trailers to help with the sheering?

I've ran P and LT and years ago ST tires on my service trailers and rv trailers. I found max sidewall pressures worked best for long term reliable service. But I also learned the hard way the folly of using too much tire for a trailers tire requirements.

There are several credible websites like Goodyear/5th wheel street.com/rvtiresafety.com/rvsafety,com/etc that recommend max sidewall pressures;

fifthwheelstreet.com
Step #5..
Selecting the Correct Tire Pressure for Your Trailer
We at Fifth Wheel St. no longer recommend adjusting trailer tire inflation pressure below the maximum load PSI rating molded on the sidewall (and only if the wheel/rim is appropriately rated) regardless of the measured scaled weight of individual tire or axle positions for all multi-axle trailers.

However, we do strongly recommend weighing individual trailer tire positions to ensure none of the axles or tire positions are overloaded. Reports have shown that trailers do not have equal weight across all tire positions. Some RV load configurations may reveal as much as 20% difference between the front and rear axle. This especially true for Toy Haulers. It is possible that mismanaged trailer load distribution will cause one end of an axle or a tire to be overloaded. It has been stated, but never confirmed by any RV Weigh master, that there are many RVs traveling on the road with at least one tire or axle side overloaded. The only way to ensure tires and or axles are not overloaded is to weigh each tire position on your trailer. Unfortunately, attempting to obtain accurate individual tire position weight is practically impossible at all truck scales. (snip).