tire pressure vs fuel economy

I went to Firestone Air Ride on the drive and tag axles. The tag has a massive 55 lb sway bar. Ride comfort is a Freedman high back polyester with eleven adjustments. The #3 support setting trades butt comfort for maybe a little too much variance between seat height and wheel. The wheel does telescope. I'm mentioning this because I think it is a disgrace that a fantastically high priced rig forces the driver to put up with a buckboard ride. I knew what I was in for on Mexican roads so no effort was spared on cabinetry and bracing. Those 1100x22.5 tires are unforgiving. I was lucky. I raided a truck wrecking yard in Reno and another in Four Courners and it's annex in Adelanto. I snared this stuff for about ten cents on the dollar.

But a fragile spine snapping seventy thousand dollar rig is hard for me to swallow.