1. READ YOUR VIN STICKER. IT STATES WHAT THE OEM SAYS TO INFLATE THE TIRES TO BASED ON THE WEIGHT AT MANUFACTURE.
2. Tires for a lot of people are out of sight and mind. Running 10lbs low for hundreds or thousands of miles will ruin a tire. It just won't be visible, until "IT JUST BLEW". GD Tire maker:B I get Motorhome tires and trailer tires way under the correct PSI all the time. Especially Motorhomes, up to 30 lbs low. Usually Trailers are around 15 to 20 lbs low.
3. I guess this is so, because it can be a pain to find and fill your RV tires when on the road. Doug