I bought some new tires today. Load Range E (10 ply). Cooper Discoverer AT3.I will not tow with this 2015 Ford F150 but the 35 x 12.50 x 20 tire size only comes in a load range E.I requested to put the tires at 35# since I am not towing.The owner of the tire business said that although I am not towing that load range E tires absolutely MUST be run at no less than 50 psi. He said the reason was that the tire will not function correctly, the truck will not ride correctly, the side wall of the tire will break down, and the there will be cupping of the tire.If this is generally true from a technical standpoint and design standpoint then I will run them at 50 psi. If I can safely run them at 35 psi and have the tire function correctly and ride properly then please let me know.Thank you very much for your technical assistance and your experience. Take care. :)

Go to the Cooper web site and see if they have a load inflation chart for those tires. I would tend to believe the dealer. 35 psi is awfully low for E range tires.

That's strange...My old 2006 Jeep Wrangler Rubicon Unlimited came from the factory with Load Range E tires. The factory inflation spec was 33 PSI front and rear for maximum GVWR and GAWR. Off-road, I "aired down" to 12 to 15 PSI.Never had a bit of tire trouble, even at freeway speeds for hours.I did rotate the tires at every other oil change, about every 6000 miles.

That's cause the tire shop owner is in the business of selling more tires. Did he put them on too narrow of rims too, to help accelerate the center tread wear even more than the over inflation would?Realistically, say 35psi holds up the front of the truck just fine now on OE size pavement pounder tires and what, maybe 30 in the rear? (I'm running 42F/37R right now on 255s P tires on my new half ton, for a bit "stiffer" ride.)Enlarge the tire and the carrying capacity per psi goes up with the increase in treadwidth and sidewall height. Quick guess, with 35s you could easily run 30F/25R for a comfortable ride. Air up from that a bit if it feels too soft.

10 ply for a daily driver? sounds like a ruff ride to me.

BB_TX wrote:Go to the Cooper web site and see if they have a load inflation chart for those tires. I would tend to believe the dealer. 35 psi is awfully low for E range tires.That's what I run all winter on the back of my 2500 for better traction. Until you get into problems with keeping the bead on the tire, if it has enough air that it is maintaining a normal sidewall profile (doesn't look low or bulged) then it is not damaging the sidewall in normal driving. If you want better handling, air up some form the load/inflation tables, or vice versa for a softer ride. This is all to be taken in moderation. Toooo low is bad just like tooooo high is bad. Better to air on the side of too high when in doubt, but if you know what you're doing with the vehicle and are traveling light, no need for more air than necessary.

Proper tire pressure for load range E 10 ply tires

Dennispel
Explorer
Apr 30, 2017
One way to find proper inflation is to find a level parking lot, draw an inch wide chalk line across the tread, drive in a straight line and adjust tire pressure up or down until the chalk is wore even across the tread. You can do this loaded and unloaded.
Grit_dog
Navigator
Apr 26, 2017
As this topic was beat dead pages ago......for anyone reading and wanting an easy straightforward answer. Find a tire loading chart for your size tire, similar model/capacity and put in a little more air than you think you have load.
djgodden
Explorer
Apr 26, 2017
schlep1967 wrote:
On my Dodge Ram 2500 the "Light Load" pressure is 45 lbs in the rear. Those are E rated tires and the door panels recommended pressure. The dealer is telling you what he thinks. Not what he knows.

x2
mkirsch
Nomad II
Apr 26, 2017
Your 12 Ram WHAT? 1500? 2500? 3500?

The door sticker for a 1500 is meaningless when it comes to an LT-E tire. That door sticker is for the stock P-rated tires as stated explicitly on the door sticker itself.

If 2500 or 3500, it is irrelevant to this conversation.
goducks10
Explorer
Apr 25, 2017
I've been running 45 PSI in my rear E's on my 12 Ram for 5 years. It's whats on the door placard. I'm not sure where all this internet guessing is coming from. E's have been run under 50 PSI for many years. Tires are aired up to the psi thats necessary for the load.
jadatis
Explorer
Apr 25, 2017
An E-load tire needs higher pressure for the same load then a Standard load P-tire.
Its because the E-load is stiffer so the overgoing curve from unloaded radius of tire to flat on the ground is larger.
This gives a smaller surface on the ground at the same deflection.
To compensate that the pressure must be higher.

But this does not mean the E-load cant go low in pressure, if the load on tire is low enaugh.
Extra reason why you need even higher pressure if your tires a Offroad or ofroad-looking with large profile blocks that cover a part of the sidewall, so lesser sidewall is left to flex.
Here a picture about it, wich I made.

but I am able to present you a pressure/loadcapacity list for your tire, made with my extra save formula , so it would sertainly not give to low pressures.

You need to give me , 1. maximum load or loadindex, 2. Loadkind already given but search if you find AT 80 psi( general for E-load) on sidewall, sometimes its for instance 77 psi for some sises, and 3. Speedcode of tire, but this can not always be found, so if not given , no problem , we will have to do without that.

But then we have a list, But determining the real weights on tires is another most difficult thing.
The car maker uses the GAWR's( gross axle weight ratings, what to law is maximum weight on the axle) to determine the advice pressures, and as long as you did not weigh, we can use that , and can mostly be found on the same plate as the pressure-advices.
If you have determined real weights, even add 10% to that for reserve, and shifted load R/L.

If you find speedcode of tires , then also the maximum speed you use and wont go over for even a minute , I would like to know.
Pressure advice is also different for other speed.

Here is a link to a map on my public map of One-drive, that belongs to my hotmail.com-adress with same username as in this forum ( so jadatis) , with in the USA map the pressure loadcapacity lists in lbs and psi, that go pretty low ( 25psi for a E-load), and made with my determined extra save calculation .

Extra save P/LC lists

also a picture in wich I try to explaine why a stiffer tire has lesser surface on the ground.
tinner12002
Explorer
Apr 25, 2017
I would have to agree with the dealer for using a minimum tire pressure to prevent uneven or premature tire wear, you do what you want but if you'd like the best wear and performance from your tires, do what the dealer says. Tires these days aren't cheap so most of us like to get the most wear possible out of them, but I'm sure some will want to argue that. Can you run 25lbs of air in your tires...sure but will you get good wear and performance from them, probably not but again its your money. I doubt any of those charts are concerned with tire wear.
jefffoxsr
Explorer
Apr 24, 2017
There are some other web sites that have the table on there and they credit TWA by saying something like table courtesy of the tire and wheel association. I don't remember which site.
riven1950
Explorer
Apr 24, 2017
http://www.michelintruck.com/reference-materials/manuals-bulletins-and-warranties/load-and-inflation-tables/#/

Do you have a link to this table? Their website looks like you have to pay for any info obtained.

Here is one example for Michelin. Mine are 18" so I ended up either chatting online with them or calling, can't remember.
Perrysburg_Dodg
Explorer
Apr 24, 2017
CapriRacer wrote:
Don,

3 thoughts:

1) Included on my web page is an analysis of the pressure spec. Short version: The vehicle's tire pressure spec did not result in an overloaded tire.
This is from Dr. Govindjee report on page 34. Seems to contradict you statement as to the affect of pressure and heat on a tire.
5.3 Thermal demands
The climate related degradation of properties that was seen in the return
tire survey points to the importance temperature plays in material behavior.
Likewise, aging studies on ideal laboratory specimens show a measurable
effect of thermal and oxidative aging. There are two major contributors to
the temperature of the tire: (1) is the ambient temperature and (2) is the
heat generation from within the tire.
1. Low inflation pressure, highway speeds, and heavy cargo loads all play
a negative role in terms of contributing to thermal aging. When all
three factors are present, the temperature rise in the belt region of the
tire can be as high as 50C over the ambient temperature.
2. When carrying heavy loads and at high speeds, decreased inflation
pressure can substantially increase tire temperature.

2) Firestone's own consultant (Dr. Govindjee) identified the problem in the tire.

I could not find where he said the tire was defective however there were higher failure rates between Firestone's two factories.
5 Conclusions
This study has found no single causative agent for the tire failures. It has
found a number of comparative differences in tire models that are likely
related to the tire failures and these are summarized below. The primary
issue that impedes additional progress is the lack of established criteria for
different types of tire failures. Development of such criteria is only today
becoming scientifically and technologically possible.

The other main point is why were no other vehicles seeing the same failure rates using the same tires that Ford was having with the Explorers? These tires were also being used on the Ford Ranger without any issues. The other thing pointing to low tire pressure and heat is that the vast majority of the tire failures were happen in hot climates.

3) The tire was recalled, but the vehicle wasn't. If the Feds didn't think the tire was the sole problem, why didn't they recall the vehicle?

The vehicles were recalled Ford had to replace those tires not Firestone. The vehicle manufacture is responsible ALL parts installed on their vehicles not the supplier. The total cost to Ford for the recall was over 3 billion dollars.

Barry