I changing my tires from a load range "D" rated at 65 lbs, to a load range "E" rated at 80 lbs. For the 65 lb "D" rated tires, the manufacture specs say to fill the dullys to 50 lbs.
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With the 80 lb "E" rated tires, what do I set the tire pressure to? Should I still maintain the 15 lb difference? Keeping the new tires at 50lb I would think would have them be way under-inflated.
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Anybody Know?

 

Look at the plate on the door jamb......should be correct as 3500's came with E-rated tires.
For what it's worth, I run 50 psi in my duals all the time......I could actually run less in them for a better empty ride, but didn't want to air them up whenever I decide to tow my Jeep around.

 

read the door, you want to make sure the dual rear tire sidewalls do not touch when loaded down, if you have a dually it should have had E load rated tires on it

3500 E rated all around
2500 E ratead all around OR D in front and E in rear
1500 C all around or C in front D in rear

these are how i usualy see them
the higher rated tires handle more weight and have less sidewall flex/ give more load and handling stability

using too low of a rated tire can be a recipie for an accident/ blowout when loaded and with a diesel or diesel dually even if you "never use it for towing or work" you still need to take into consideration the weight of the vehicle and do what is recommended by manufacturer to ensure optimal ride and handling

just my $.02

 

I have kind of a different take on tire inflation. I don't pay any attention to what the vehicle manufacturer says. A tire acts the same whether it's on vehicle A that weighs 6000 lbs. or vehicle B that weighs 6000 lbs. I inflate tires purely based on what it says on the sidewall.

My truck is a 2500, so what I run for pressure in the rear tires is irrelevant to your situation. I think if it were me, I'd run the E tires at max sidewall pressure (80 psi) and see how the ride is. If it's too harsh, drop it 10 lbs and see how it is. I wouldn't go below 50 lbs. empty. You'll also want to make sure both tires on a given side don't get so squishy that they touch sidewalls.

Tires that are properly inflated run much cooler than underinflated tires, and they give you better fuel mileage as well.

 

The problem with this, is that the tire contact patch will get smaller, as the air pressure causes the tread to bow outward. Overinflation not only decreases tread life, but it also hydroplanes easier in wet conditions, and handles poorly in normal conditions. Every tire runs differently on the same vehicle, and the chalk line is the best way to figure out the proper pressure for the tire.

I use sidewalk chalk, then roll the truck forward to ensure the wear is even across the entire tread area. Using this method, I have ended up running 55psi in the front, and 50psi in the rear.

 

I think seahawk is right on the money. I run my E rated tires the same way, I only take them up in pressure for heavy loads. Best for ride quality. The tire specs only givr you max ratings for loads. The minumum is your preference.

 

Well, we're not talking overinflation here--just max sidewall pressure. Besides, I only recommended it as a starting point to proceed from to determine the desired pressure. The chalk method sounds like a good way to determine that. I don't run max sidewall pressure in my rear tires either when empty.

 

Mine are rated at 80 psi cold. I am currently running them at the door sticker suggested pressures and am seeing even wear and good mpg.

 

First get an accurate axle weight then take the sidewall rating of x lbs @ y psi which will tell you how much air is required for any given load up to the max weight listed for which you will need the max psi.

 

I run 55 front and 70 rear towing my fiver. I drop the rear to 50 not towing. my fiver has 1800 pin weight.My last set of tires lasted for 800000 m and wore even, so I must have got the air set correct for my truck.

 

800000 miles is a little unbeleivable Don T.

Better re-check your figures, or did you go by the overhead computer?!!

 

I can believe his numbers...
I ran a 80K mile tire on my 4-runner for 110K miles..I found the tire too slick in most cases but it ran 110K miles..

-dkenny

 

80k miles might be believable but he said he got 800k miles. I doubt a steel wheel would get that. Obviously Don just typed in one too many 0's

 

Thanks everyone for your input. It was my dumb. I got the truck with D's on it. I read the sticker for the pressure but never noticed those ratings were for E's. I've been eating up tires. Towing I have been running with max sidewall rating. It's no wonder I haven't been getting any milage out of them. I had just kept replacing them with the same tire. By setting the new "E" tires to the sticker, I bet the tires will last longer. I think I'll try Don T's suggestion and run 70 in the rear dually when towing.

 

Try the method I listed above it takes a little effort but it absolutely works for any given weight & once you have it done one time you can then figure out how much air is needed for any load.