I just got off the phone with Cooper (the MFG of my tires). They confirmed that for my axle weight I should be running 55 pounds in all tires. The also confirmed some I knew but isn't talked about much here, "Tire footprint". If you over inflate the footprint will get smaller and affect handling. Which would account for the poor handling when I had them inflated to 80 pounds. I remember when I owned a Corvair and an AMC Ambassador station wagon. The Corvair front tire pressure was supposed to be 15 pounds, due to the engine in the rear. The Ambassador had tires one size larger than the sedan and also required 15 pounds in the front. On both of the cars if you had 30 pounds of pressure the handling became very spooky and the Corvair was downright dangerous. Remember "Unsafe At Any Speed", it was all about tire pressure. Trying to get a "Pump Jockey" to put just 15 pounds in the front was often difficult and may required a gun!
1992 HR Imperial 5000; 33 foot F53,460 gas.