What PSI should my tires be at? Should they be the same in the front and rear or higher psi in the front?

I have a 2015 Ford F-250 crew cab, short bed, 4x4 6.7ltr diesel and I don't haul anything ever. My tires say 35 x 12.5R 20LT Load E and the outside of the tire reads 65 max psi. But I know you're not suppose to fill them to that. Can anyone help me out.

If you can't trade it in and get a reasonable truck then try 35 PSI cold. Those tires are not for riding around, gas mileage or tread wear anyway so nothing you can do will make them good.

Open the driver's door and look for a placard (sticker) that shows the proper tire size and inflation pressure for the tires that came on the truck from the factory. The same information should be in your owner's manual. When in doubt, try actually READING it!

Did your truck suddenly gain weight? Tire pressure is based on vehicle weight and the manufacturer's expected handling characteristics. Larger tires need more air volume, but the exact same pressure as is listed on the vehicle.

Don't know what the label on your truck says, but my dodge diesel requires more pressure in the front due to the engine weight.

Every modern vehicle on the planet has an information sticker posted on the door frame which includes tons of useful information about the specific vehicle, including the automaker's recommendation for tire PSI. The recommended tire PSI is vehicle specific, regardless of make or model of tire.