As several have said, the max psi rating on the tire is for the max load rating of the tire. As said, the true vehicle inflation is never more than that, or they have specified the wrong tires for that application. It is usually less than the value on the tire. Vehicle tire pressure effects ride, handling, braking, fuel economy, & tire life so the mfg should consider all this in recommending a pressure. As an automotive development engineer, if done proplerly it is complex. The BT cruiser I had, had the door frame sticker, which came from Ford, and then 2 additional stickers on the exterior of the cab behind the drivers door. Both were higher pressures in the rear than the OEM sticker. Neither were date or referenced the other. So I concluded that there was change made after Gulfstream built the vehicle. Obviously Gulf stream is careless with the info, and Ford has no idea how the vehicle will be configured and the nor the weights or weight distribution, they are just delivering a cut a way Ford Van. The Ford sticker is just general info and not specific. My own experience was not to inflate to 80 psi when traveling as the ride impacts were horrible and I didn't want to jar the coach apart. I used 65 psi, but I did travel with minimum fresh water and mostly empty grey and black tanks, but full fuel tank. The former is all located at the very rear on my RV, so that is the worst configuration for load on the tires. Just passing on my vehicle experience, but if you want to optimized consider that you may be operating at minimum weight or near GVWR and there is not 1 best number for both. Just never run underinflated for the conditions you are operating
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