RVGuy1966, sounds like your dealer didn't do the PDI (pre-delivery inspection properly). Tires are shipped with too much pressure in them on purpose to keep them from getting flat spots while sitting. The same thing is true on automobiles. I use to work as a tech. at a dealer so I know. Part of the PDI is to adjust the pressure in the tires to the proper psi. One doesn't want to operate the vehicle with over pressure tires. 70 psi is probably what they where shipped at pre PDI. They should have been adjusted to 50 psi but in your case but weren't.
2011 5.7l Toyota Tundra w/ Roadmaster Suspension.
2014 Jayco Eagle 338 RLTS w/ 7hp gen & 1000w invert.
PowerTwin II-30" Electric RV Leveling Stabilizer.