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.

You don't list the model of BFGoodrich tire in question. They make several in that size and ply rating.

The Tire itself doesn't matter, it's the size and rating that I indicated at the top of the page that I have.

My question is strictly for owners of F150s who have the Load C, LT Tire option available from the factory when ordering.

One gentleman said 40 psi which I don't know if it's correct. Ford may have been in error putting that on the placard.

With my BFGoodrich All Terrain TA KO tires, Discount tire said 41 psi. WIth that air pressure, the tires feel flat with more noise, vibration, and poor fuel mileage than I would think it should be.

I called BFGoodrich and they told me that 41 psi was way to low for my tires. They said the Ford OEM load range for a P275/65R18 is 2601 lbs at 35 psi. The replacement tires MUST have the same load range or above.

The BFGoodrich All Terrain TA KO2 tires offer 2660 lbs at 55 psi. That's the correct tire pressure for any LT275/65R18 as there is a tire chart that states tire loading vs air pressure for LT tires. Same for "P"assenger Tires.

The LT tire at 41psi only offers a bit over 2100 lbs rating which is way to low as the factory OEM tires were 2601 lbs.

BFGoodrich said the tire wear would be correct at 55 psi and would not wear correctly at such a low 41 psi.

BUT I know the truck doesn't need 2601 lbs rating per tire and was wanting to know what Ford actually states on the door jam placard for the air pressure on a Load C LT tire. Load C and Load E air pressure vs load ratings are the same for differing air pressures, but load C tires max out at 50 psi (2535 lbs) while load E tires go up to 80 psi with a load rating of 3415 lbs.

If everyone's truck does show Ford recommending 40 psi with the Load C, LT tire option, I'll like just keep my BFGoodrich tires between 50 and 55 psi as they ride so much better, but a bit stiffer obviously.

All load/inflation tables for tires sold in the USA are identical for the same size/type of tire. Brand name doesn't matter - if it's sold in the USA it has to comply with the Tire and Rim Association (TRA) load/inflation tables.


http://www.us-tra.org/

Yoyo is a Japanese company, but if you compare their load/inflation tables to the ones published by Firestone, you'll see they are identical for the same size/type of tire.
https://toyotires2-1524598101.netdna...0623_Final.pdf

So the load/inflation table for your BFGoodrich tires is identical as the Firestone and Toyo load/inflation table for the same size/type tire.

Note that neither Firestone nor Toyo includes all size tires in their load/inflation tables. If they don't sell that size/type tire in the USA, then there's no need to include it in their load/inflation tables.

If you want to see the complete load/inflation tables for all sizes/types of tires sold in the USA, you need to get a copy of the TRA annual report. But only members of TRA receive that report, and membership is expensive. (Somebody has to pay the TRA engineers that develop the load/inflation tables

Members (including BFGoodrich and Toyo) can pick and choose the tires in the report that they want to include in their load/inflation tables.

It seems a inflation table is meaningless apart from a actual axle weight, from a scaled truck, not a door sticker max number if ride quality, tire wear and reliability is paramount. Change the load a thousand pounds and everything changes .

Granted. A load/inflation table is designed to be used only to determine the PSI required for the load on the tire. That means you have to know the actual weight on each tire, and the best way to determine that is by weighing the wet and loaded rig on a CAT scale.


However, in my experience, I've learned that if you pump up the tires to match the load/inflation table, or maybe 5 PSI more than the load/inflation table requires, then your tires will easily pass the "chalk test" and maximize tread life and reliability. Ride quality is what it is, but proper inflation per the load/inflation table will usually give you the best ride quality. Replacing worn shocks with Bilstein or similar high-quality shocks can improve ride quality a lot more than under-inflation or over-inflation of the tires.

40 is what I run..

THANK YOU, you are the second person showing that 40 psi. I originally thought that was in error from Ford, but 2 out 2 suggests it's correct.

How's the ride, noise, vibration, and mileage? At 41 psi, my tires didn't seem right. Perhaps the difference between Load C and Load E tires.

At 40 psi, it has 2130 lbs weight rating per tire. That's 4260 lbs per axle which still exceeds the axle rating, but anything less than 35 psi will be under the 3850 lbs axle rating and potentially be a dangerous situation. Components can be pushed past limits a bit, tires can't from what I've seen happen to others. I'd like to have some cushion, at least more than 5 psi. Surprised Ford cut it so close when they didn't have to.

FYI, Government requires new trucks/cars to have TPMS and they're set to go off when PSI goes down by 25%. The funny thing is that if you go by P series 91% of rated load for SUVs and light trucks. That equals 47 psi on an LT tire. At 25% under that 47 psi, it equals 35 psi which is 1940 lbs rating or 3880 lbs axle rating. Anything lower will be under the 3850 lbs axle rating. With the OEM P series tire, at the 25% under inflation of 35 psi is 26 psi. The P tire at 26 psi rating at 91% is 2056 lbs / tire or 4112 lbs per axle.

So with the P series OEM tire, it will cover both the 3850 lbs rated and 4050 lbs rated axles. But using an LT tire will need to be even higher than 47 psi to cover the 4050 lbs rated axle at the 25% under the rated inflation psi.

The 40 psi for the Load C LT tire option just doesn't make sense to me, but it's there none the less.

Is it possible you’re way over analyzing this? One might argue, why would you buy a 10+ ply E-rated tire designed to run at 80psi netting maximum load coverage of 3400# when in reality you only need a tire that can support 2300# or whatever your RGAWR is? Then in an attempt to only use what you need from the overkill tire, you plan to inflate to half its intended pressure since you don’t require the full load support. That sounds like all kinds of wrong to me.

Just because the E-rated tire can deliver the needed 2300# of load at a lower pressure doesn’t mean the tire is designed (tread wear, contact pattern, heat dissipation) to be operated at said lower pressure.

You asked for opinions so here’s mine; air them up to 60psi and run the crap out of them. You’ll get more load then the rest of your rig can support (tires no longer the weak link), plus you’ll get better performance while towing from the increased pressure (firmer sidewall, less wallowing). Sure the ride is rough, but you can’t have your cake and eat it too.