E load tire pressures for daily use and how I came to it.

[TNrob]

I used Google to find a Firestone commercial tire loading and pressure pamphlet.

This is the PDF page that I found.

According to it the minimum tire pressure required to set both front and rear axles to 5360 pounds for a LT275/70R18 (my Ram 2500) is 50 psi.

I went through weigh tickets from my existing TT and my old 1500 and found that the most the TRUCK ONLY rear weight above daily use on any trip was 620. The most the TT tongue weight ever scaled with fresh tank full and a load of baggage and food was 700 pounds. So I add 700 heavy tongue to bed full of firewood and come up with 1320. I round to 2000 with heavy duty new truck because I can.

New truck scales at 3000 rear and 3960 front, full of fuel and all sorts of truck stuff like tow straps, tie downs, jumper cables, etc., and my emergency bug in backpack full of too much stuff to recount--but no she or me.

I arbitrarily took new truck rear and added a rounded up 1000 pounds each for both excessive cargo plus excessive tongue weight and came to 5000 pounds rear axle. I looked at the table and found that 50 psi in the rear tires would readily accommodate 5360. That's 10 psi below factory recommended 60 psi for the front axle--whether loaded heavy or light--though not quite enough to carry the factory front axle rating of 5500 pounds.

Front axle is only 4000 pounds, and even heavily loaded (for my purposes) with 2000 pounds of tongue and other cargo, with even half of that distributed to the front axle rather than the rear; front axle will never carry more that 5000 pounds.

Again consulting the Firestone pamphlet, I determine that 50 psi in all four tires will more than cover anything I throw at my truck tires whether running light to work and back, hauling a big load of home improvement from a box store, or pulling my current camper loaded even to its GVWR of 6800 pounds. It's overkill, even.

TPMS system be danged. I will deflate my tires to 50 psi all around before I leave for work in the morning. At 50 psi it will be safe to do all I ever ask of the truck or the tires, and after I scale it a time or two with camping cargo loaded and hooked up I'll adjust it from there if I decide it might be lowered. If I ever find the perfect 5er I'll up it to 80 in the rear and 60 in the front for towing.

FCA will get a nasty-gram this week on the hazards of over inflated tires and the willful negligence required to put millions of such vehicles on the road in an effort to avoid a few extra paragraphs in the owners manual designed to educate owners on the proper management of tire pressure.

If anyone finds a flaw in my above inflation logic, please let me know so that I can better adjust both my understanding and my tire pressures.

And before I make an *** of myself in my nasty-gram to Ram.

Cheers from East Tennessee.

[Cummins12V98]

JIMNLIN wrote:

JW2 wrote:
TNrob:

Did you ever hear back from Ram or NHTSA?

The thread has been dead for over 4 years so the OP most likely has moved on as nothing in his profile shows up.

PartyPooper!

[JIMNLIN]

JW2 wrote:
TNrob:

Did you ever hear back from Ram or NHTSA?

The thread has been dead for over 4 years so the OP most likely has moved on as nothing in his profile shows up.

[specta]

With my camper loaded I run 80 psi in the rear and 70 psi in the front.
With my truck empty I run 50 psi in the front and 45 in the rear.
My tires always wear even across the tread.

When I first bought my truck the TPM was set at 65 psi and my first set of tires wore prematurely in the middle so when I replaced the first set I had the tire store disable the TPM so I could run what ever pressure I wanted without the stupid light coming on and so I don't have to relearn it every time I rotate my tires.

[Grit_dog]

Case in point to an old but good thread dug up here....

"New" truck has 37-12.50 Toyo heavy load tires on 20x12s. Tires are 65psi max tires for like 3800lbs capacity.
Previous owner had all 4 around 60 psi. Idk how many miles, but tires are like new on the outside edges of tread and the middles are wore down about 4/32ths on the front and 6/32 ths on the rears. Time to rotate, but basically he just wasted 20% of the tread life by over-inflating the tires.
At $500 a pop, he pissed away $400 by not knowing how to air up a tire right!
The irony is, is the TPMS (2500 RAM) has not been re-programmed with lower limits, so he still had the tire pressure light shining the whole time anyways!

I dropped the fronts to like 42 psi and the rear to 30 psi last night. BAM, better wet traction, smoother ride and tires aren't trying to eat themselves! (Yes this is plenty of pressure for a 3/4 ton diesel with tires that size. I'd run these tires, 30F/25R in a snow storm and laugh the whole way as it drive like it has tracks!)

Bad part is, the nanny vehicle mfgs almost require overinflating of truck tires, because the general public is too stupid or disinterested to know a single d@mn thing about how their vehicle operates!

Not rocket surgery. I learned it before the internet existed. More air for more capacity, less air for less capacity. More air for better mileage, less air for better traction....novel concepts.

[Cummins12V98]

Use chart based on your weights. Add 5 rear and 10 front to what psi the chart dictates.

Your tread wear will be perfect.

My 2500 4x RAM I would easily get 100k with BFG’s and 120k with Michelin’s.

[wopachop]

Didnt read it all but could it be to get better mpg ratings?

[JW2]

TNrob:

Did you ever hear back from Ram or NHTSA?

[msgtord]

I contacted Nito and gave them my vehicle info and was told to keep my air pressure at 61 front and 65 rear when unloaded.

[Grit_dog]

TNrob wrote:
This is the letter I sent to Ram. I'm sure it will result in nothing.

The recommended pressure for front axle tires is 60 psi, with axle load rating of 5500 pounds. The recommended pressure for rear axle tires is 80 psi with axle rating of 6500 pounds. According to Firestone, the manufacturer of the factory installed tires, the pressure required for even rear axle max load weight rating is 70 psi. For normal load of 3000 to even 5000 pounds on the rear axle, 50 psi is more than adequate according to Firestone. At 50 psi a load range E tire can carry 2680 pounds, giving an axle capacity of 5360--well over the daily weight for most non-commercial drivers.
Ram has previously recommended two tire pressures for the 2500 series, with a light load pressure and a heavy load pressure. On previous models Ram even provided owners a switch to toggle between loads according to their present needs. This switched the TPMS from one warning point to another so that owners benefited from the low pressure warning system whether lightly or fully loaded, and allowed for proper inflation rather than over inflation during light duty operation.

In subsequent years the toggle was removed, but owners could still have their servicing dealership adjust the computer set points to a proper daily pressure below the factory set points. I attempted to have this done at my dealership and their effort was unsuccessful. It appears that Ram has locked the computer and disabled any reprogramming of the low tire pressure set point.

Over inflated tires not only wear poorly, they are dangerous. Over inflation greatly reduces the tread patch that contacts the road surface, causes excessive and unnecessary bouncing, increases the risk of tire damage from pot holes, and basically provides for an unsatisfactory driving experience. I'm certain the engineers at Ram are aware of these facts because in previous years they provided for BOTH light and heavy service inflation. It is utterly unacceptable and grossly negligent for Ram to recommend, and basically require, that owners operate their 7000 pound vehicles on tires inflated to carry over 13000 pounds. Ram is causing possibly millions, certainly hundreds of thousands of truck owners, to unwittingly endanger themselves and others on highways around the country with these dangerous tire inflation recommendations.

I can think of no reason beyond laziness and penny pinching that might induce a manufacturer to so grossly endanger the lives of their customers and their families—not to mention everyone else that shares the roadways with them. Ram MUST immediately notify their customers of the unsafe driving conditions they have been knowingly subjected to by their trucks’ manufacturer. Ram MUST alert dealerships and issue a “flash” for them to install on trucks that have been delivered to customers in this unsafe condition.

I await a response.

Good for you, bravo man!
The TPMS limits on class 2 trucks is one of the most ill conceived bs deals on these newer trucks, and your correct, Ram updated their Witech software and this is no longer re-programmable.
However, your letter is directed at the wrong entity.
Send it to the NHSTA instead as its their mandate.
Unfortuanlty the outcome will likely be the same.

[Grit_dog]

wanderingbob wrote:
I believe on my Ram 2500 , 2014 , that the TPMS system will learn the pressure that I am satisfied with and adapt the dash to my satisfaction . When I make a radical change in tire pressure the display will flash until I have stopped and started a few times . I think that I could just turn key off and on several times and do the same . I like it to flash as it bothers my wife !

I wish you were right, but you're not, unless something is defective with your truck.

[Grit_dog]

Hondavalk wrote:
X2 with mowermech. A primitive but workable way to check is to pour some water in front on a tire and observe the the tread pattern it lays down on dry pavement.

Or let some air out til they pooch and then fill til the bulge juuust goes away. Redneck tire gauge!

[Grit_dog]

mrgrim007 wrote:
I just got finished setting up my new TPMS on my Suburban tonight. Door jam says 50 PSI front, 80 rear. So that's what I put them at. Did some Googling and some people go with the door jam, others don't. We're headed to Wyoming next week on a trip (not towing anything) and I plan on keeping the PSI where it's at...mostly because that's what the door jam says.

But now after reading this I'm reconsidering...

Reconsider, unless you want a rough ride and potentially unnecessary center tire wear.
the 50/80 is for max axle loading or gvw or something more than empty.
Seriously.

[wanderingbob]

I believe on my Ram 2500 , 2014 , that the TPMS system will learn the pressure that I am satisfied with and adapt the dash to my satisfaction . When I make a radical change in tire pressure the display will flash until I have stopped and started a few times . I think that I could just turn key off and on several times and do the same . I like it to flash as it bothers my wife !

[TNrob]

This is the letter I sent to Ram. I'm sure it will result in nothing.

The recommended pressure for front axle tires is 60 psi, with axle load rating of 5500 pounds. The recommended pressure for rear axle tires is 80 psi with axle rating of 6500 pounds. According to Firestone, the manufacturer of the factory installed tires, the pressure required for even rear axle max load weight rating is 70 psi. For normal load of 3000 to even 5000 pounds on the rear axle, 50 psi is more than adequate according to Firestone. At 50 psi a load range E tire can carry 2680 pounds, giving an axle capacity of 5360--well over the daily weight for most non-commercial drivers.
Ram has previously recommended two tire pressures for the 2500 series, with a light load pressure and a heavy load pressure. On previous models Ram even provided owners a switch to toggle between loads according to their present needs. This switched the TPMS from one warning point to another so that owners benefited from the low pressure warning system whether lightly or fully loaded, and allowed for proper inflation rather than over inflation during light duty operation.

In subsequent years the toggle was removed, but owners could still have their servicing dealership adjust the computer set points to a proper daily pressure below the factory set points. I attempted to have this done at my dealership and their effort was unsuccessful. It appears that Ram has locked the computer and disabled any reprogramming of the low tire pressure set point.

Over inflated tires not only wear poorly, they are dangerous. Over inflation greatly reduces the tread patch that contacts the road surface, causes excessive and unnecessary bouncing, increases the risk of tire damage from pot holes, and basically provides for an unsatisfactory driving experience. I'm certain the engineers at Ram are aware of these facts because in previous years they provided for BOTH light and heavy service inflation. It is utterly unacceptable and grossly negligent for Ram to recommend, and basically require, that owners operate their 7000 pound vehicles on tires inflated to carry over 13000 pounds. Ram is causing possibly millions, certainly hundreds of thousands of truck owners, to unwittingly endanger themselves and others on highways around the country with these dangerous tire inflation recommendations.

I can think of no reason beyond laziness and penny pinching that might induce a manufacturer to so grossly endanger the lives of their customers and their families—not to mention everyone else that shares the roadways with them. Ram MUST immediately notify their customers of the unsafe driving conditions they have been knowingly subjected to by their trucks’ manufacturer. Ram MUST alert dealerships and issue a “flash” for them to install on trucks that have been delivered to customers in this unsafe condition.

I await a response.