Originally Posted by Chuckinca
The door plate on my Ram 3500 states max rear tire pressure when loaded is 75 PSI and 45 PSI with light load.
What is the major advantage in running the rear tires at a much lower pressure?
lower pressure = smoother ride. To get the smoother ride the tire flexes to absorb road variation. More flex=>temperature to the sidewall and air pressure. Increase the load and flexure increases as does temperature hence the increased recommended pressure to reduce flexure of the sidewall.
Two ways to check for correct pressure:
1. Is the tread wear equal across the tire?
2. Is the temperature equal across the tire?
Of course the first is a long term (5000miles?) evaluation while the second can be checked after perhaps as little as 50 miles of highway travel.