I'm getting ready to take the 04 Ltd Hemi on vacation. I'll be carrying up to 1,000 lbs payload and running 75-80 for 10-12 hours. I've been looking at one of the inserts that came with the manuals about tire inflation for loads/higher speeds. Does anyone increase the inflation pressure for higher speeds, or is the 33 psi on the door placard good enough? I have the stock Ltd wheels.