A good place to find tire specs is http://www.tirerack.com/index.jsp

 

Each tire has it max PSI listed on the sidewall some where. Most of the time load range D tires do not go up to 70psi, more around the 50 psi area.

If you are concerned with fuel mileage, you can still run high psi in a load range D tire and achieve the same results.

It really comes down to you driving style and what you haul all the time. If you haul/tow a lot I would stick with the load range E. More plys, better load ratings, and will last longer under a lot of stress. I personally have a load range C tires on my truck. Thats what it came with when I bought it. I dont haul that much and when I do tow something, I inflate the tires to max pressure and havent had an issue.

The last thing that I want to say about load ranges, is the higher you go, the more stiff the tire is and will effect ride quality. If you put load range E tires on an empty 1500 all the time, it will be a rough ride. But put the same tires on a 3500 CTD and it will feel normal.

Those are some ideas that will help you figure out the right tire.

 

I run E load tires on my QC. I keep them at 53-55psi, and the ride is fine. There has not been any adverse tread wear. I have not towed anything or carried anything more than a few hundred lbs in the bed. I did start out out 70+ psi, then gradually dialed them back to where I felt comfortable. I even emailed Nitto to get their recommendations, after providing vehicle info, etc... they suggested 45 psi.

If I ever do tow anything "large", I know I can simply air up (and change my programmer setting as well)...

I am sure that C and D will provide a softer overall ride, but I am OK if my truck rides like a truck.

 

My load E's which are 325/45/24s require 65psi

 

My load E's which are 325/45/24s require 65psi

Sure glad I don't got that problem!

I had Nitto E rated tires. Kept them at 50 front and 45 rear.

Sounds like you need a E rated tire if you want the high pressure for fuel..

 

A lot of times the larger tires don't use as much pressure. Something to do with the larger tires holding more air and therefore don't use as great a pressure. I remember when I was a kid the old Monster trucks like Big Foot and Miss All American would come down to Cypress Gardens and have water races with their big flotation tires and they were only inflated to around 16-20psi.

 

Well, wouldn't a D rated tire running at 50psi be about as heavy riding as an E running on 70psi?

Since I don't really haul/tow much, I'm thinking I might be better off using the D tires when I get my new set.