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

[Mike_Up]

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.

[TurnThePage]

The last P rated tires I put on my old F150 had a max PSI of 44. At that pressure, they performed pretty well, but if they were aired down anywhere under 40 PSI, there was lots of tail wagging. So far the P rated tires on my new Ram 1500, inflated to 45 PSI, are performing very well. I will still replace them with LT tires when the time comes, but I'm in no hurry.

[Mike_Up]

Fordlover wrote:

1. EPA regulations require MFG'ers to maximize fuel economy, and LT tires don't do that.

Towing, I actually got my average fuel economy on them. In fact maybe a bit better considering I drove through some good wind. I got 10.5 mpg. My high is 11.0 mpg with this truck over the last few years.

When I had the 2010 F150, looks identical to this except no chrome package, I got between 10 - 10.5 mpg with the lower powered 5.4L 3V.

The difference is the 2010 came with true All Terrain tires, the Michelin LTX A/T 2 passenger tires. They weren't as quiet as the Goodyear Wrangler SR-A passenger tires on my 2012 but were so much better in the snow and off the pavement. Ford said the 2012 was suppose to come with All Terrain tires but gave me the Goodyear Wrangler SR-A street tires, most likely for mileage as you said.:R

Commuting, maybe about 1/2 a mile to 1 mile loss compared to the Wranglers but it's too soon for a definite result as my routes have changed and I just now settled on an air pressure.

[Fordlover]

Mike Up wrote:

After having both, I really don't know why makers put P series tires on trucks. I can see it on Full Size SUVs that are essentially grocery getters, but trucks are meant to do work.

Glad you are pleased with the new tires. It's good to keep in mind when replacing P tires for us RVers.

As far as why the P tires on trucks, because:

1. EPA regulations require MFG'ers to maximize fuel economy, and LT tires don't do that.

2. The majority of truck owners commute in them (at least in my tiny city of ~6 million people) and aren't towing or hauling a load when they do. This also contributes to item #1.

[Pooter]

pitch wrote:
Pooter,are you 13 years old,does your mother know you are on the computer?
Why would you say something idiotic and totally unrelated to the thread?

1. Perhaps a little less coffee in the morning will go a long way to solving your problem. I made a tongue in cheek joke. You responded by throwing personal insults and attacks. Do you really want to talk about maturity and intelligence after your response?

2. While we are at it, perhaps we can talk about reading comprehension. He was talking about towing stability, trucks and white knuckling . How is a heavier duty truck not related to that?

3. It's the nature of the internet. Someone starts a thread and others offer up opinions......

4. Why did you not attack the guy above talking about his F-350?

[pitch]

Pooter,are you 13 years old,does your mother know you are on the computer?
Why would you say something idiotic and totally unrelated to the thread?

[Pooter]

Mike Up wrote:
Did my first tow on the new tires and what a difference. Can't believe how more stable the ride is.

With the P series, a gust of wind would hit the rig and push me a bit. Then the rig would wobble a bit left to right until it stabilized. With constant wind gusts, this made driving a definite 2 handed job and sometimes with white knuckling it.

With the new tires, we had a lot of wind from previous rain storms. While the wind pushed me like before, it was a none issue, and the rig maintained it's stability with absolutely no wobbling left to right! This is why I bought these tires. It's like a night and day difference. One handed driving was easy but I still use 2 handed driving with the rig for safety.

The LT tires (10 Ply E Load rating) are only a bit stiffer unloaded but offer a more stable, confident ride empty. I actually prefer it to the empty ride of the P series that had poorer handling and more bouncy ride from the softer tires.

After having both, I really don't know why makers put P series tires on trucks. I can see it on Full Size SUVs that are essentially grocery getters, but trucks are meant to do work.

The real work trucks all start with a 2

[Mike_Up]

Did my first tow on the new tires and what a difference. Can't believe how more stable the ride is.

With the P series, a gust of wind would hit the rig and push me a bit. Then the rig would wobble a bit left to right until it stabilized. With constant wind gusts, this made driving a definite 2 handed job and sometimes with white knuckling it.

With the new tires, we had a lot of wind from previous rain storms. While the wind pushed me like before, it was a none issue, and the rig maintained it's stability with absolutely no wobbling left to right! This is why I bought these tires. It's like a night and day difference. One handed driving was easy but I still use 2 handed driving with the rig for safety.

The LT tires (10 Ply E Load rating) are only a bit stiffer unloaded but offer a more stable, confident ride empty. I actually prefer it to the empty ride of the P series that had poorer handling and more bouncy ride from the softer tires.

After having both, I really don't know why makers put P series tires on trucks. I can see it on Full Size SUVs that are essentially grocery getters, but trucks are meant to do work.

[Mike_Up]

I emailed BFGoodrich about the correct tire pressure going from a P series to a LT series. They said the 47 psi is correct. Also said the prior phone rep was wrong at 55 psi.

Said Discount tires pressure of 41 was too low.

So I'll try the chalk test at 47 psi. Don't think 2 psi is going to change much.

[CWSWine]

Tystevens wrote:
.

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.

My neighbor search for 6 months for HD Tow and HD Payload because he didn't want to deal with the "Wash Board Ride" of F250. Couple of months ago I took him for ride in my F350 and both of us agree that the ride is worse in his 2014 F150 than my 2015 F350. Since mine was F350 he said hard to find a parking place because of the length. So quick trip to the website and my F350 Super Cab is 232.4 inches and his F150 is 231.9 - but he does have more leg room in the back seat.

Getting off "P" tires when towing is the right thing to do...

[Mike_Up]

Thanks everyone, I did do the chalk test. 55 psi was over inflated. Tires were hot at 50 psi when I did the test, and next morning the cold air pressure was 45 psi. When it stops raining, I'll double check.

Since the manufacture keeps both tires at the same psi, I'm doing the same.

The front tire came out pretty much perfect with even wear on the chalk all the way across from driving in a straight line. The rear tires wore even all the way across to 3/8" from the edge of the tread. That 3/8" tread still had dark chalk while the rest was wore.

Since the tires are at the same pressure, show good even wear, and ride, vibration and noise seems to be still good, I'm going to leave it there. The rear axle isn't loaded with the trailer or gear right now so it will likely wear better when loaded. BUT I'm going to keep them at the same tire air pressure as Ford does that with OEM P series tires and the LT option LT C Load tires.

I guess the E load Tires may wear a bit different than the C load tire.

[Tystevens]

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]

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]

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]

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.