Butch has it right. Why deliberately disable an important part of your suspension, and reduce traction, handling and overall safety, by running tyres harder than they need to be according to the tyre manufacturer's recommendations.
In addition to that setup - which covers running at maximum rated tyre speed on paved roads - I have another set of pressures whenever I get onto gravel roads. That is reduce the pressure to 80% of normal and drive at a maximum speed of 50mph. If the roads are badly washboarded or rougher, then the pressure goes down some more and the speed goes down accordingly.
I use the same methodology in setting pressures on all vehicles - from the 17 ton bigrig down to the little Suzuki
