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Mike_Up's avatar
Mike_Up
Explorer
Sep 04, 2015

2009 -2014 F150 XLT Crew 4WD "LT C-Load Tire Option"

I'm trying to find the correct air pressure to air my new LT 275/65R18 E1 tires to.

Discount tire is telling me 41 psi which I know is under inflated by the noise, tuffer rolling resistance, poor mileage, and vibration it created.

BFGoodrich is telling me 55 psi which would be correct if my OEM P series tires were had a load rating for a LT tire but they don't they have a load rating for a P tire.

P tires rating have to be lowered 9% due to a regulation if the "P"assenger tires are put on SUVs or Trucks to handle the higher ride height, truck applications, and possible overloading.

So if that the case, the rating should be 47 psi on the new LT E1 tires I bought.

Load E and Load C handle the same weight per psi, up to the C load ranges max of 50 psi.

So those who have an XLT 4WD Crew Cab with the LT275/65R18"C" option tires, what's your door jam placard say to air your front and rear tires at. I really think it's 47 psi.

BTW, I did air up to 55 psi, the ride, noise, vibration, and mileage mirrors my old OEM P series All Season tires but the tires a bit stiffer as one would expect.

I'm fine with airing to 55 psi, but I'm thinking 48 psi is the correct psi.

My OEM P tires are rated at 2601 lbs at 35 psi (max load), my new LT275/65R18E tires are rated at 3415 lbs at 80 psi (max load) and rated at 2400 lbs at 47 psi.

The OEM P tire rated at 2601 lbs at 35 psi is for a car only. 91% of that rating is it's true rating on an SUV or Truck. That rating is now 2367 lbs at 35 psi.

So 47 psi on the LT equals the same load rating as the P series at 35 psi.

So are your tires all rated to be aired to 47 psi??

BTW, here's Firestone's Tire load/size chart. Couldn't find one for BFGoodrich.
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  • Tystevens's avatar
    Tystevens
    Explorer
    Sep 08, 2015
    I don't know about stickers and all of that, as my F150 came w/ P tires from the factory. But I've been running my LT-E range Michelins at about 50 psi for a little over a year now (16k miles), and they are doing just fine.

    Yeah, the ride is rougher than it was w/ 35 psi P's on it, and the mpg went down by about 1 mpg on average.
  • jerem0621's avatar
    jerem0621
    Explorer II
    Sep 05, 2015
    One thing you may be able to try is dealing with your Static Load Diameter. Basically, the tire is designed to be 32.1 inches round.

    Something you can do is measure from the center of the hub to the ground until the distance is 16 inches. You may have to air up the tire or air down the tire depending on what your starting pressure is. I have a suspicion that once you get the hubs 16 inches off the ground your MPG and noise will improve. Ride may as well.

    You will need to do this empty and loaded... once you get the hubs 16 inches off the ground take a note of the PSI so you can maintain those pressure's loaded a unloaded.

    Thanks!

    Jeremiah
  • Mike_Up's avatar
    Mike_Up
    Explorer
    Sep 05, 2015
    I have the exact same axle ratings as you (3750lbs front, 3850 rear) even though it has the 3.55's. Payload rating as per door sticker is 1540lbs.


    With the heavier tires, my payload would be about 1540 lbs.

    Wow, that's to low for my tires. I lost about 2 mpg and tire noise and vibration was worse. The truck also was working more like the tire was too flat.

    Maybe 55 is higher than I need, but the ride is very good with a bit more stiff. Airing down a bit more will likely still be good but taking some of the stiffness out.

    I read a few people who did the chalk test with the 2009 - 2014 F150, and they air between 50 and 55 psi and said the chalk test was right on at those pressure plus had better wear.

    I guess it would be nice if I could get a conclusive answer from Discount tire and BFGoodrich but they are so far off from one another.

    And I've read that E rated tires require more air pressure for better wear and fuel economy which seem spot on from my limited findings.

    Thanks everyone
  • go_jets_go's avatar
    go_jets_go
    Explorer
    Sep 05, 2015
    I have the exact same axle ratings as you (3750lbs front, 3850 rear) even though it has the 3.55's. Payload rating as per door sticker is 1540lbs.
  • rhagfo's avatar
    rhagfo
    Explorer III
    Sep 05, 2015
    Mike Up wrote:
    go jets go wrote:
    I have pretty much the exact same truck as you except mine came from the factory with the Goodyear Wrangler ATS load range C tires. They are supposed to be inflated to 40psi according to the sticker on the door jamb.


    Wow, at 41 psi, I had vibration, noise, poor mileage, and they felt flat with it harder to accelerate than normal. I put them to 55 psi as to what BFGoodrich said, and they felt great. My mileage went up about 2 mpg, vibration went away, tires didn't feel flat and acceleration the same as with OEM, and tire noise went away.

    I'm really surprised at 40 psi because the load rating on a LT tire is so low, I can't believe Ford would do that.

    What payload rating did they give you on the tire placard?? Also, what axles to you have. I have 3750 lbs front axle and a 3850 lbs rear axle.

    That 40 psi blows me away. How's your ride and do you get decent mileage with the tire aired that low??

    A member at the F150 forum took a pic of tire loading sticker on his F150 HD Payload package truck. That truck has a 4050 lbs front axle and a 4800 lbs rear axle. The truck comes with LT245/75R17E tires. His placard states 55 psi for the front 4050 lbs axle and 60 psi for the rear 4800 lbs axle.

    Thanks for the help.


    Well based of your empty weights you need to work to get the right pressure. while 40 might be a bit low, I would think for your load (empty) 55 psi is too much, I would be looking at between 45 and 50, and and maybe 55 to 60 in the rear loaded.

    You can always run the chalk or tape test on the tires to see tread contact. Keep in mind those tires are capable of carrying about twice the GVWR of your TV. :B
  • BenK's avatar
    BenK
    Explorer
    Sep 05, 2015
    Balancing the tire at the wrong PSI can have it smooth as silk at 'that' PSI and
    bounce all over the place when aired to a different PSI...

    I always insist that they balance my tires at mas sidewall listed. Then
    have them re-balance them after about 500-1,000 miles (when they are
    broken in)

    Just talking PSI is out of context without the tire class/size/etc and the
    load being placed on it

    I have LT class, load range C tires on my Silverado and the sidewall says
    maximum 35 PSI...so just going by the 'one size fits all' LT load range C
    would have my 33/12.5R15LT C's over inflated
  • Mike_Up's avatar
    Mike_Up
    Explorer
    Sep 05, 2015
    go jets go wrote:
    I have pretty much the exact same truck as you except mine came from the factory with the Goodyear Wrangler ATS load range C tires. They are supposed to be inflated to 40psi according to the sticker on the door jamb.


    Wow, at 41 psi, I had vibration, noise, poor mileage, and they felt flat with it harder to accelerate than normal. I put them to 55 psi as to what BFGoodrich said, and they felt great. My mileage went up about 2 mpg, vibration went away, tires didn't feel flat and acceleration the same as with OEM, and tire noise went away.

    I'm really surprised at 40 psi because the load rating on a LT tire is so low, I can't believe Ford would do that.

    What payload rating did they give you on the tire placard?? Also, what axles to you have. I have 3750 lbs front axle and a 3850 lbs rear axle.

    That 40 psi blows me away. How's your ride and do you get decent mileage with the tire aired that low??

    A member at the F150 forum took a pic of tire loading sticker on his F150 HD Payload package truck. That truck has a 4050 lbs front axle and a 4800 lbs rear axle. The truck comes with LT245/75R17E tires. His placard states 55 psi for the front 4050 lbs axle and 60 psi for the rear 4800 lbs axle.

    Thanks for the help.
  • go_jets_go's avatar
    go_jets_go
    Explorer
    Sep 05, 2015
    I have pretty much the exact same truck as you except mine came from the factory with the Goodyear Wrangler ATS load range C tires. They are supposed to be inflated to 40psi according to the sticker on the door jamb.
  • Mike_Up's avatar
    Mike_Up
    Explorer
    Sep 05, 2015
    tcp wrote:
    Look at the door sticker. It will give the exact PSI specified for the OEM tires. I had a rental 2015 f150 with LT tires. The door said 51psi. The tpms in the centre display showed 47psi on all 4 tires with no warnings. Ran a bit harsher than I would like. 1893 lb payload rating on the sticker.


    My truck came with "P" series tires not LT. I put LT on as in my 1st post. They are not the same type of tire. LT tires have lower load ratings at 35PSI while having much higher load ratings at 80psi or 50 psi.

    Look at the manual link I provided to see the difference between the tires.

    Does anyone have the LT C load Tire option on their 2009 - 2014 F150???
  • tcp's avatar
    tcp
    Explorer
    Sep 05, 2015
    Look at the door sticker. It will give the exact PSI specified for the OEM tires. I had a rental 2015 f150 with LT tires. The door said 51psi. The tpms in the centre display showed 47psi on all 4 tires with no warnings. Ran a bit harsher than I would like. 1893 lb payload rating on the sticker.

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