Go Back   F150online Forums > Powertrain & Mechanical > Wheels, Tires & Brakes
Sign in using an external account
Register Forgot Password?


Wheels, Tires & Brakes

Reply
 
 
 
 
Thread Tools Search this Thread Display Modes
  #1  
Old 03-18-2012, 02:03 PM
Senior Member
 
Join Date: Apr 2010
Location: USA
Vehicle: 2010 Ford F150
Posts: 165
Tire Pressure For Load Range E

Just bought a set of Cooper Discovery AT3's (275/70/18 E rated). After I got home I thought they looked a little soft. I checked the PSI and they were all at 35. This after drving at highway speeds for a couple hours. I thought that was a little low for an E rated tire. I have run E rated before and never had them lower then 45psi. I called Discount Tire where I just bought them and the salesman told me that the truck called for 35psi and it doesn't matter what the rating is. This dosen't sound right to me. Any opinions?
Reply With Quote
  #2  
Old 03-18-2012, 02:28 PM
Senior Member
 
Join Date: May 2011
Location: Gainesville, Georgia
Vehicle: 2005 Ford F150
Posts: 505
You can run them at 35 PSI and not have any problems if you don't do any hauling/towing etc IMO. I have the STT's (E Rated) and run 40 in mine. It really just comes down to how much towing/hauling you do and personal preference.
__________________
2005 F150 STX SCAB 4.6 4x4
SI/DO Flowmaster Catback Super 50 Series, K&N 77 Series CAI, PHP Gryphon (with custom tunes), 6" Zone Offroad Lift, Bilstein 5100s on front and back, 17x9 Fuel Throttles, 35 12.50 17 Cooper STT's, 20% Tint on front/back windows and back glass, 50% tint on windshield, tow mirrors, 2011 STX Decals on bed, Blacked-out emblems and badges, Silverstar XZE bulbs
Reply With Quote
  #3  
Old 03-18-2012, 03:30 PM
Senior Member
 
Join Date: Apr 2010
Location: USA
Vehicle: 2010 Ford F150
Posts: 165
Quote:
Originally Posted by spencerdrewh View Post
You can run them at 35 PSI and not have any problems if you don't do any hauling/towing etc IMO. I have the STT's (E Rated) and run 40 in mine. It really just comes down to how much towing/hauling you do and personal preference.

At this point I'm not towing or hauling anything with any weight so I'm really under utilizing these tires, but 33/35 psi made the tires look low. I'm more worried about uneven wear. I aired them up to 40psi cold and they look better and I didn't really sacrifice any ride quality. Guess I'll stay at that PSI and just keep a watchfull eye on the tread.
Reply With Quote
  #4  
Old 03-18-2012, 03:34 PM
Senior Member
 
Join Date: Dec 2003
Location: Mount Airy,MD
Vehicle: 2009 Ford F150
Posts: 6,550
Quote:
Originally Posted by Fishhawk460 View Post
Just bought a set of Cooper Discovery AT3's (275/70/18 E rated). After I got home I thought they looked a little soft. I checked the PSI and they were all at 35. This after drving at highway speeds for a couple hours. I thought that was a little low for an E rated tire. I have run E rated before and never had them lower then 45psi. I called Discount Tire where I just bought them and the salesman told me that the truck called for 35psi and it doesn't matter what the rating is. This dosen't sound right to me. Any opinions?
45 should be your minimum. As far as Discount tire saying for the truck it is 35 no matter what tire, they are idiots. If that were true, why for F150s that come with LR E tires is the recommended 50. Or with LR C 40 or 45. I can never understand how a company that even on their website state running too low is dangerous can have their people come out with such stupid comments.
35 is definitely too low, even for an unloaded F150. The tire does not even have half it's load carrying ability at that pressure, which is far below the GAWR or even unloaded weight of the front axle.
Reply With Quote
  #5  
Old 03-18-2012, 05:40 PM
Senior Member
 
Join Date: Feb 2007
Location: Lockport, La.
Vehicle: 2013 Ford F-150
Posts: 4,210
I agree with Kingfish 35 psi is way too low on a LT tire.
__________________

2013 Platinum 4x4...Ingot Silver with pecan interior...Ecoboost with 3.31 Elec.lock rear...Huskyliner's front and rear...F150 bed mat...BakFlip VP bed cover...Toyo 275x60x20 AT2's... Tinted front's...Bilstein 5100's front and rear...Boost Bar.
Reply With Quote
  #6  
Old 03-18-2012, 08:38 PM
Senior Member
 
Join Date: Apr 2010
Location: USA
Vehicle: 2010 Ford F150
Posts: 165
I've always run E rated tires at 45psi or higher. I have them at 40 now. I might give it a coouple weeks and bump them up to 45. If the ride quality doesn't change I'll go with what I've always gone with in the past.
Like I said, it didn't sound right to me.
Reply With Quote
  #7  
Old 03-18-2012, 09:12 PM
Senior Member
 
Join Date: Dec 2003
Location: Mount Airy,MD
Vehicle: 2009 Ford F150
Posts: 6,550
Quote:
Originally Posted by Fishhawk460 View Post
I've always run E rated tires at 45psi or higher. I have them at 40 now. I might give it a coouple weeks and bump them up to 45. If the ride quality doesn't change I'll go with what I've always gone with in the past.
Like I said, it didn't sound right to me.
Unless those tires have a max pressure of 65, 40 is still too low. The truck weighs in at around 5400lbs at least, with most of that in the front. At 40, those tires at best handle have their max weight or around 1800 lbs. Which is probably right at what the front of the truck weighs in at. Ad any load or passengers, and you are over that weight.
PS - Vehicle that come with a LR E max 80 psi tires will have their TPMS fault set at 46 psi. Since this is a vehicle that normally does not come with LR E (only the 8200lbs GVWRs do), you have a little leeway, but I would not leave it at 40.
Reply With Quote
  #8  
Old 03-18-2012, 09:53 PM
Senior Member
 
Join Date: Oct 2009
Location: Corona, Crazyfornia
Vehicle: 2003 ford f150
Posts: 2,230
I don't have "E"s but the door sticker is only good for the stock tires or equal. I agree that your pressure is too low, look on the tire and it will tell you what the MAX pressure is and stay below that.

Mine have a 44psi max and I run them around 38-40. I always stay under max because heat will raise the pressure if you are running air, nitrogen........I don't know.
__________________
Love my box stock V-6
Reply With Quote
  #9  
Old 03-18-2012, 10:06 PM
Senior Member
 
Join Date: Jun 2002
Vehicle: 2002 Ford F-150 5.4L
Posts: 4,196
Quote:
Originally Posted by jgger View Post

Mine have a 44psi max and I run them around 38-40. I always stay under max because heat will raise the pressure if you are running air, nitrogen........I don't know.
That's not a completely accurate explanation because the max pressure on the side of the tire is based on a cold (non-opeating) pressure. The manufacturer understands this. In other words, you tire has a max of 44 psi. If you fill it to 44 cold and it raises to 52 hot going down the freeway, that's A-OK. If you're loading a particular tire up to its max weight capability, you need to have it pumped up to that max pressure.

Nitrogen pressure will not vary with temperature. That's the so called 'benefit' of using it, but it's pretty impractical in a daily driven environment. Pretty much a sales gimmick.
Reply With Quote
  #10  
Old 03-18-2012, 10:06 PM
Senior Member
 
Join Date: Apr 2010
Location: USA
Vehicle: 2010 Ford F150
Posts: 165
Quote:
Originally Posted by jgger View Post
I don't have "E"s but the door sticker is only good for the stock tires or equal. I agree that your pressure is too low, look on the tire and it will tell you what the MAX pressure is and stay below that.

Mine have a 44psi max and I run them around 38-40. I always stay under max because heat will raise the pressure if you are running air, nitrogen........I don't know.

The MAX PSI on a load range E tire is 80. I'm certainly not running these tires just below that. No need. Even when i drove an F350 I ran those tires at around 55 unless I was towing a 8000lb boat. And at 55 psi the truck rode like a tank. I'm going to play with these tire on the F150, but will probably settle with 45. That is the PSI I have been running for the last 20K miles on the Goodyear Silent Armours, and they look like they are new.
Reply With Quote
  #11  
Old 03-19-2012, 02:46 AM
Senior Member
 
Join Date: Oct 2009
Location: Corona, Crazyfornia
Vehicle: 2003 ford f150
Posts: 2,230
I forget that alot of people drive their truck around empty, I use mine for work. It always has about 500 lbs in it minimum, so that is why my tires are just under the max pressure. You guys are right, if I was running empty then I'd probably drop my pressure a smidge too. My bad.

Also had a friend that had a warrentee turned down because of over pressuer, his were inflated to max at cold. When they checked them hot he was like 7lbs over.

When I had my 3/4 ton it called for 80 psi too, I ran them at around 65 most of the time but pumped them up for a load.

Anyhoo I still think 35 is way too low, that would probably make them wear on the outside more than the center. I think you are on the right track to air them up a tad......and the tire store guy is wrong. IMHO
__________________
Love my box stock V-6
Reply With Quote
  #12  
Old 03-19-2012, 09:00 AM
Senior Member
 
Join Date: Jun 2002
Vehicle: 2002 Ford F-150 5.4L
Posts: 4,196
Quote:
Originally Posted by Fishhawk460 View Post
The MAX PSI on a load range E tire is 80.
The max psi on an E tire varies from tire to tire. My E rated Wrangler MT/R-K's are 60.
Reply With Quote
  #13  
Old 03-23-2012, 05:40 PM
Senior Member
 
Join Date: May 2002
Location: PA
Vehicle: 2008 Ford F150
Posts: 150
I just put Nitto Terra Grapplers LT 275/70-18 LR E on my truck. Nitto recommended 42psi front and rear when I emailed their tech department. I will use that as my minimum.
__________________
08 SuperCab 4x4, 5.4L. Silver W/Chrome Package
Dynomax 19387 Cat-Back
Reply With Quote
  #14  
Old 03-23-2012, 05:53 PM
Senior Member
 
Join Date: Dec 2010
Location: Chandler, Tx
Vehicle: 2002 Ford F-150
Posts: 127
I run 45 in my Michelin LT265-70/17E's. Truck rides a little firmer but it's an FX4 Screw. I like the road feel
Reply With Quote
  #15  
Old 03-23-2012, 05:58 PM
Senior Member
 
Join Date: Apr 2005
Location: New York
Vehicle: 2005 FORD F-150
Posts: 569
Quote:
Originally Posted by Fishhawk460 View Post
Just bought a set of Cooper Discovery AT3's (275/70/18 E rated). After I got home I thought they looked a little soft. I checked the PSI and they were all at 35. This after drving at highway speeds for a couple hours. I thought that was a little low for an E rated tire. I have run E rated before and never had them lower then 45psi. I called Discount Tire where I just bought them and the salesman told me that the truck called for 35psi and it doesn't matter what the rating is. This dosen't sound right to me. Any opinions?
Get hold of Cooper and tell them what tire you have and what you have it on and they will give you the proper PSI for your application.
http://us.coopertire.com/Contact-Us.aspx
Reply With Quote
Old 03-23-2012, 05:58 PM


 
 
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


All times are GMT -4. The time now is 07:58 PM.





This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company
 
Contact Us Advertising Privacy Statement Terms of Service Jobs Forum Text Archives
Emails & Contact Details