I've got a set of:

Nitto Terra Grappler tires
LT325/70R17

on my Super Duty and I wanted to know what the correct PSI should be. The sticker on the door says 75 PSI/cold, but all 4 of my tires right now have around 35/36 PSI, do I need to pumped them up to around 75 PSI or are those tires made to run with 35 PSI??

Thanks!

I'm posting this because I want to hear what others are running at, even though I believe I have my answer. Nitto's website has a disclaimer saying not to inflate to over 40 PSI (Death or Serious Injury May Result) but the tire says to run at 50 PSI. I guess I could go with what the tire states and fill to 50 PSI.

 

The pressure that is stated on the door is for stock tire sizes. Use the tire pressure that is stated on the outside wall of your current tire.

 

36 is way to low, your truck weighs a lot more than a passenger car. Put them as close to the number on the tire as you feel comfortable with. The more tire pressure the stiffer bouncier it will feel. Mine say 80 and I have them just above 60.

 

Are the Nitto's E rated? E rating usually has a Max 80 psi. I usually run 70psi in my E rated tires. Most of the time I am hauling or towing. 60-70 should be good for around town. Check the tires' sidewall it will give you a max psi rating.

 

When I carry weight on a longer trip I put them to the max. The weight takes the bounce/stiffness away.

 

One sign that 36 is way too low is that if you had a TPMS it would be set off! The TPMS on my 2010 goes off at 55 front (60 spec'd) and 65 rear (70 spec'd).