What is the tire air pressure for a ford e350?

The tire manufacturer imprints the max psi on the side wall of their tires. You shouldn't go higher than that maximum, but it is not necessarily the best pressure to put in.

Ford E350s use heavy-duty tires, typically with a max pressure of 80 psi. Unless you are carrying a very heavy load though, 80 psi will be more pressure than you need. My mechanic set my tires to 55 psi, and I typically air the rear tires up to 70 if I plan on running it full of people back there. (And if you're not running it full, you might as well just be driving a truck or a minivan).

Most vehicles have a recommended air pressure on a decal inside the driver's door frame. It's important not to underinflate or overinflate your van's tires, as it can lead to tire failure, extra brake wear, and even increased risk of rollover in an accident if your tires are overinflated or underinflated.