With our ST tires we run them at or very near to max psi to keep them from
overheating which can lead to tread separation. When I don't have my toys along with us while RVing in our TH, our ST tires still stay at max psi although they are rated to carry over 3K# more. Got 3 years out of our TH's stock china-bombs and are on or 5th season with our current set of Maxxis ST 8008 tires.
We have to use interstates and highways to get anywhere in our neck of the woods and towing at those speeds last thing I want to worry about is if my ST tires might have a catastrophic failure due to overheating from under-inflation. Over 8 years with our current TH and we have been fortunate to never have a blowout or even a flat due to a slow leak. Having steel valve stems definitely has its merits.
LT tires are a different story and manufacturers have inflation tables based on the weight they are expected to carry. Our Chevy HD calls for inflation to be at max 80psi according to door placard, but since they are capable of handling much more weight than they actually carry with TH attached, we run them just over 70 psi to make the ride a bit less harsh.