I have a 2005 Ford F250 Super Duty Power Stroke Diesel. It has BFG Rugged Trail T/A tires LT265/70R17. Load Range E.

What is the lowest pressure that I can run for everyday driving (not carrying a load). I am in need of a smoother ride. 75 psi is really rough.

 

I also have a 2005 F250 SD and when I got the truck I rode around on the pressure from the factory and thought the truck was quite spongey feeling. After some investigation, I aired the tires to the recommended psi listed on the tires. The air pressure you run in your tires is based on your comfort and your discretion. A low inflated tire will only wear quicker on the outside portion of the tread and middle of the tread will not wear as fast. Much like an over inflated tire will wear quicker in the middle with less wear on the outside. The amount of required air pressure or proper air pressure is recommended to provide you with the longest and best usage of the tires currently on your truck ans is stamped on the tire. I know nothing of the liabilities you will come across by running your truck with low air pressure. I am a volunteer fire/ems personnel and taking the air pressure of a vehicle's tires after collisions and such are now a common practice with state troopers.