In another thread, I mentioned that there was an SAE paper that might be useful as a resource on using high tire pressures.
SAE Paper 800087 – The Effect of Inflation Pressure on Bias, Bias-Belted, and Radial Tire Performance - by B. L. Collier and J. T. Warchol, B. F. Goodrich, February, 1980
I've posted a summary here:
Barry's Tire Tech
Enjoy!