That's what I'm thinking of doing. After they tell me a minimum of 45 I'll forward it to the meat-stick-know-it-all kid that told me 35 was okay.
Like I said earlier, it didn't sound right to me and I've never run less then 45 in a E rated tire.

 

So I just got some Nitto trail grapplers LT305/55/20. The tire says max PSI of 65. The shop set them at 38. Do you think that is to low? If so what should they be?

 

According to 02RegularCab4X4 on post #13 in this thread you're 4 lbs light.

 

In this case it is apples and oranges. 02RegularCab4X4 tires handle 3640lbs at max 80 like yours, Notch46 handle 3195lbs at max 65. Although 02RegularCab4X4's are a bit low, I would not go below 45, even unloaded.
For Notch46, 38 is a bit low, especially if you have your vehicle loaded or tow. I would not go below 40 on those and if fully loaded or towing, I would bump to 45.

 

^^^ Someone was sleepin' in Chemistry class

ANY gas varies in volume (hence, in pressure under containment) with temperature. That's a fundamental property of a gas and Nitrogen is not exempt from the laws of physics.

Air is 78% by volume nitrogen already, and the benefits are as much a gimmick anyway. There is some very small improvement of pressure loss over time due to the higher percentage of larger molecules in Nitrogen.

A 'boutique' gas, to keep yer tires fuller, but empty yer wallet faster

LR 'E' - follow manufacturer's recommendations, or Kingfish's - NOT the dumb tire monkeys.

 

Yeeaaaaa, I know that; wasn't sleeping. Was just sayin that 'as a general rule' for the purpose of this thread.

 

My truck is unloaded most of the time. So ill bump it up to 40psi and see how it does. Thanks

 

Taking into consideration the different manufacurer recommondations. This may be somewhat of a generalization, but I think the concensus is that if your E rated tires have a max psi of 65, the minimum you can run them with the truck unloaded is 40. If the max psi is 80, the minimum you can run them with the truck unloaded is 45.

 

Unfortunately, not quite true. You have to look at each tires specs. There are LR E tires with a max pressure of 80 and a max weight of 4000lbs at that pressure. In that case that min would be about 40. There are also some that are not near that weight, where the min probably should be around 50.

Just have to look at the specs for each. Unfortunately some manufacturers are not listing all their specs online.

 

Like I said.
"Taking into consideration the different manufacurer recommondations. This may be somewhat of a generalization"

 

 

i have the bfg 275/70/18 wich are e rated as well, when i had them installed they did the same thing to me. I called bfg and they did a calculation on what my trucks said and what tires i had before and said they need to be at 50psi. I would call your tire company and see if they have a recomendation. Also when i had them at 35pis it felt like i was pulling a ton of weight and took a while to get up and go. Once i put 50 psi in them it was smooth sailing.

 

I emailed Nitto and for my setup they say 42psi. I will try that and see how it feels.

 

Just got off the phone with Cooper Tire and they agreed with the guy at Discount Tire. They told me to run the psi that was marked inside the door. It has nothing to do with the tire rating, just the psi rating for the vehicle.

 

And they are totally wrong. Whoever you talked to has not got a clue. Those same tires if they came on the F150 would have 50psi marked on the door.

PS - As I mentioned, the recommended pressure for my LT LR C tires is 45. If what the Cooper guy stated was true, all F150s would say 35. Far from it. I had thought about Cooper tires for my next set, specifically At3, but with employees like that, I think they are off my list.