Rear tire pressure dually

[Obewan]

Just changed from a TT with 1200lb tongue weight to a fifth w approx 4000 pin weight. Haven't gotten to the scale yet. I'm confused.... placard on truck door says tires rated at 2660lbs at 65psi for rear duallies. Michelin load rating says 2778 at 80psi for duals. Should I inflate to 65or 80psi? Didn't have to think about this as much with only 1200lbs. Always kept it at 65.

[webecreekin]

Cummins12V98 wrote:

Mile High wrote:

webecreekin wrote:
I ran 65 in my rear tires with my pin weight at 3400 pounds and they rubbed together. The result after 600 miles was a big bulge in the sidewall of the tire. They weren't touching in a static setting, but while flexing going down the road, they were touching. Cost me four new tires. The inflation charts and the scientific approach don't mention the tires touching.

Wow, I had never heard of that.

I would say they were not the correct size tires.

Stock tires. In fact, they were the originals.

[webecreekin]

Cummins12V98 wrote:

Mile High wrote:

webecreekin wrote:
I ran 65 in my rear tires with my pin weight at 3400 pounds and they rubbed together. The result after 600 miles was a big bulge in the sidewall of the tire. They weren't touching in a static setting, but while flexing going down the road, they were touching. Cost me four new tires. The inflation charts and the scientific approach don't mention the tires touching.

Wow, I had never heard of that.

I would say they were not the correct size tires.

[Cummins12V98]

Mile High wrote:

webecreekin wrote:
I ran 65 in my rear tires with my pin weight at 3400 pounds and they rubbed together. The result after 600 miles was a big bulge in the sidewall of the tire. They weren't touching in a static setting, but while flexing going down the road, they were touching. Cost me four new tires. The inflation charts and the scientific approach don't mention the tires touching.

Wow, I had never heard of that.

I would say they were not the correct size tires.

[Cummins12V98]

rhagfo wrote:

wandering1 wrote:
Follow what is on the tires, Michelin had a reason for putting that on the tires. What is on the door is wrong if it is not for the brand and size tires you have on the truck.

:S :S :S

The number on the sidewall is for the MAXIMUM LOAD, Michelin provides inflation charts for loads less than the Maximum the tire is designed to carry. Using the proper inflation for the load provides better wear and better traction and control!!!

Me thinks you be correct SIR!

[Cummins12V98]

I like pictures! I think a few of you may know that by now. I also like to give examples to backup what I have to say when I am able to.

Here are Michelin MS2's with 40K on them. I ran 45 psi rear unloaded and 60 loaded with 5K pin. The fronts always had 80psi. This was on my 2011 RAM Dually.

Weigh your rig! The fact is most people overinflated the rears and under inflate the fronts.

With my 2015 I am running 40psi on the rears solo because the rears on the 11 had "SLIGHTY" less tread in the centers than the edges on the rear tires running the above pressures.

My 15's front axle weighs 5,460# or 2,730# per tire. I could run 70 with little extra or 75 but with the edge wear the tires wear evenly at 80.

[jadatis]

Though weighing per wheel( pair) or axle is the best way to determine the loads ,in lack of that you can use the Gross Axle weight rating of your rear axle of your towing truck.
For law you are not allowed to go over that , even when towing a 5th wheeler.
You can mostly find that on the same plate as the pressure advices.
From your tire we already know 2778lbs AT 80 psi for dual so E-load.
Need to know the speedcode .

From TT you gave dual load rear axle so 2 twinwheels on the axle.

But when you are busy also give details of front of TT and 5th wheelers tires and GAWR's and number of axles and total number of tires, Probably ST tires or else give speedcode too.

Then I will do the whole calculation and give advice with maximum reserve with acceptable comfort and gripp and no bumping

[rhagfo]

wandering1 wrote:
Follow what is on the tires, Michelin had a reason for putting that on the tires. What is on the door is wrong if it is not for the brand and size tires you have on the truck.

:S :S :S

The number on the sidewall is for the MAXIMUM LOAD, Michelin provides inflation charts for loads less than the Maximum the tire is designed to carry. Using the proper inflation for the load provides better wear and better traction and control!!!

[sdetweil]

My 2012 Ford Dually has a a strange hop at about 60mph if I run the tires at the max rated on the door tag (60psi gives max 9000lb RAWR)
when towing my FW (2800 lbs on pin)

if I raise the cold pressure to 75-80, then the hop goes away. 65 or 70 is not enough.

it rides like glass at 75psi tho..

the hop at different speeds has been reported by many for a long time.. 1st back in 98 I think. Some trucks do it, some don't.
my 08 2wd DRW, and 12 SRW did not.

[MARKW8]

webecreekin wrote:
I ran 65 in my rear tires with my pin weight at 3400 pounds and they rubbed together. The result after 600 miles was a big bulge in the sidewall of the tire. They weren't touching in a static setting, but while flexing going down the road, they were touching. Cost me four new tires. The inflation charts and the scientific approach don't mention the tires touching.

That would be hard to believe with OEM size tires. My 3500# TC doesn't do that at 60#.

Mark

[MARKW8]

2008 GMC CC dually and 15,500# 5er with 3300# on the pin. The door sticker says 65# frt and 60# rear. That's what I've always run. No tire problems and no bad wear. 77.000 miles, 40k on oem Generals the rest and still going on Firestone TransForce HTs. I expect another 10k +.

Mark

[Mile_High]

webecreekin wrote:
I ran 65 in my rear tires with my pin weight at 3400 pounds and they rubbed together. The result after 600 miles was a big bulge in the sidewall of the tire. They weren't touching in a static setting, but while flexing going down the road, they were touching. Cost me four new tires. The inflation charts and the scientific approach don't mention the tires touching.

Wow, I had never heard of that.

[webecreekin]

I ran 65 in my rear tires with my pin weight at 3400 pounds and they rubbed together. The result after 600 miles was a big bulge in the sidewall of the tire. They weren't touching in a static setting, but while flexing going down the road, they were touching. Cost me four new tires. The inflation charts and the scientific approach don't mention the tires touching.

[Coach-man]

rhagfo wrote:

Obewan wrote:
Just changed from a TT with 1200lb tongue weight to a fifth w approx 4000 pin weight. Haven't gotten to the scale yet. I'm confused.... placard on truck door says tires rated at 2660lbs at 65psi for rear duallies. Michelin load rating says 2778 at 80psi for duals. Should I inflate to 65or 80psi? Didn't have to think about this as much with only 1200lbs. Always kept it at 65.

Well if you inflate to 80 psi that is a total of 11,112# of capacity, do you need that much?

At 65 psi you have 10,640# of capacity, so hit the scale and get your loaded and unloaded weights, my guess is 65 psi is more than enough.

X2, inflate your tires depending on the load, no need to run at 80 PSI with rough ride if 65 or 70 lbs will handle the load.

[Helmsey]

We Cant Wait wrote:
Put your truck on a scale with the 5th wheel hooked up and see what your weights actually are. The go to the Michelin tire inflation chart and determine by your actual weight what your REAL tire pressure should be.

+1 Know your weight and know how what PSI will accommodate that.

I would be willing to be that the 65psi that the truck mentions has to do with a capacity rating on the truck itself. I'm betting that Dodge figured out something on that truck (rear axle?) has a limit of 10,640 pounds and with 65psi in the tire it has enough capacity to cover that.

[TXiceman]

Look at the tire manufacturers load chart and Add a 5 psig to cover you loaded condition. The door tag is for the trucks 'Rated load". I have found that when we are towing, I get a better ride and handling if I go to 70 psig on all six tires. When not towing, I run 65 up front and 50 to 55 psig in the rear.

Ken