Better ride when not towing?

Here's an update: front tires are at 65, rear duals are at 60, just took the TT on our first long haul 1200 mi total. I will weigh tomorrow when I fuel, the ride was awful most of the time until I passed OK state line, so this is a road problem. Only on Oklahoma highways so far have we driven in these concrete "expansion joint" highways I believe they are called, where every section is raised a bit and results in a constant "tha-thunk tha-thunk". So far the costly toll turnpike to Hugo was the worst and nothing but smooth roads (occasional rough patches as normal) since, we just crossed into Alabama tonight.

Edit: Also this is not a daily driver so I would appreciate advice on towing conditions only. 30psi in rear on stock size tires when towing, with road temps rising now, is asking for a blowout at 75mph. All valid points about lowering pressure to improve ride but don't forget while towing, this raises heat fast in summer causing tire failure if not pulling over frequently enough to let them cool.