As Ron said, max sidewall is only for max weight. I ran max sidewall on my new Yokos (125 psi) until I could get the rig weighed and found the tire manufacturer's chart said I could run 90 psi. I added 5 for extra cushion. The difference in ride was incredible. The bridge joints didn't jar the coach as much and there was less lane movement when the semis went by.
Running 95 psi, my TPM get up to 109 on the road.
Jerry & Jeanne
1996 Safari Sahara 3530 - 'White Tiger'
CAT 3126/Allison 6 speed/Magnum Chassis
2014 Equinox AWD / Blue Ox