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

brulaz
Explorer
Apr 14, 2017
When I put LT-Es on my F150, I contacted Michelin, told them the front and rear tire pressures and sizes/types of the OEM tires (as on the yellow sticker on the door jamb).

They came back with front and rear tire pressures for my new LT-Es so that they would match or exceed the weight ratings of the OEM tires at the OEM pressures.

You can do the same yourself, perhaps using the front and rear GAWRs as a short-cut to the OEM tire weight ratings. LT-E tire inflation tables are readily available.
schlep1967
Nomad
Apr 14, 2017
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.
The_real_wild1
Explorer
Apr 13, 2017
Yes you can run them at 35psi. I made the mistake of having tires done on my new 1/2ton in 2008. They rode rough and it wasn't until a few days later I checked the sidewall and sure enough they were e rated tires. I should have taken them back but didn't. Ran them at 38psi for 4 years until I got rid of the truck. I suggest to keep an eye on them for the first couple months to make sure they are wearing good and adjust pressure if needed. Even run them at 40spi if the ride is good.
jefffoxsr
Explorer
Apr 13, 2017
Thanks for the the info guys. This tire, and others I have looked up ONLY come in a load range E in this size.

We will likely tow with this vehicle in a few years but for now since we are not towing I would like to have a softer ride.
Grit_dog
Navigator
Apr 13, 2017
midnightsadie wrote:
10 ply for a daily driver? sounds like a ruff ride to me.

It's only as rough as you make it. 35psi in a E load tire will only ride slightly stiffer than 35 in a C load tire. Air holds the vehicle up. Tires just keep the air corralled and provide traction.
Grit_dog
Navigator
Apr 13, 2017
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.
midnightsadie
Explorer II
Apr 13, 2017
10 ply for a daily driver? sounds like a ruff ride to me.
Grit_dog
Navigator
Apr 13, 2017
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.
mowermech
Explorer
Apr 13, 2017
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.
BB_TX
Nomad
Apr 13, 2017
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.

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Proper tire pressure for load range E 10 ply tires

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