I put Michelin Defender LT tires (load level E) on my 2015 Ram Laramie. I took one trip with the tires inflated to 75 lbs and about shook my truck to pieces on some of the roads on our way to Texas with my 7,600 lb (dry weight) TT. I let out 10 lbs of pressure and continued on my way@ 60 lbs and WHAT A DIFFERENCE in the ride quality.
When I got home, I sent a e-mail to Michelin requesting a recommendation on air pressure for my towing level. I got a very pleasant surprise when a Michelin technician called me to discuss this subject. After we talked about total loaded weight of the trailer and the 900 lbs tongue weight he recommended that I keep the E rated tired inflated to 52-55 lbs all the time, when towing and when not towing. He calculated the weighs and used the Michelin air pressure to load capability data to make this recommendation. I have since towed the trailer with the tires inflated to 57 lbs ( just a couple lbs extra for peace of mind) on a 1,000 mile trip and the trailer and truck were rock solid and the ride very comfortable.
The "moral of the story" is, it's the air that carries the load and the tires only need to be inflated to the degree that they will carry the load they are designed to carry at a particular air pressure. So why "over" inflate them to carry several hundreds of pounds that are not present when you tow your trailer. Inflate to match the weight!!!
Days camping (2016)----181 days
Days camping (2017) --- 52 days
2016 Wildcat MAXX 28RKX (33' TT), 2007 13' Scamp
2015 Ram Laramie Hemi, w/air suspension
30 years RV'ing
12 different RV's