Putting too much air in the tags will transfer more weight to the front wheels and less ground pressure on the drives, Eds Newell is a 1987 with 11r-24.5 tires,
I found these pressures to work the best with this coach, although I only put about 3000 miles on it. It would be best to take some time at a scale to adjust them. I set them to where it handled the best, the newer coaches may have a different set-up, some I believe have a pressure limiting valve that wont let more than 60 psi into the tag. Here is a thread on a 88 with the same questions..
http://www.luxurycoachlifestyle.com/...djustment.html