To add an additional layer to this discussion, there is an RV mobile weighing fellow who uses computer flat plates to weigh each tire. The RV needs to be loaded as it will generally be driven. He then recommends the tire pressure for each wheel.
Full disclosure I don't buy into that sales pitch. I can see a small difference in weight from left to right (just the sofa on the right side VS kitchen with refrig/water heater/pots and pans/etc on the left side. I don't see any difference front/rear on the same side. His rational is that the proper PSI will extend tire life.