I just finished changing the rear differential fluid. To make the job a little easier, I removed the spare and before putting it back, I checked the air pressure. It had only 35 pounds. My door sticker calls out 55 in the fronts and 80 in the rears (max load).
I've had the truck for 5 months now and this was the first time I checked it. I'm sure 35# would be OK until you could get to an air machine in a non-towing situation, but if you were pulling some serious weight, maybe in the rain or in the mountains, it could be a bit more risky.
Just wanted to suggest that it might be a good idea to check that spare if you haven't already. The valve should be on the 'downside' of the tire up in the holder so you don't really even need to drop it to check it.
* I gotta say that changing that differential fluid was EASY. Filled it back up with AMSOIL Series 2000 75W90.
** Thanks everyone for all the great on-target info. I've asked several questions and always got helped out.
Tim B.
