Tire pressure — should I bump up the pressure on my truck's tires?

[dmbecke]

I would get higher load rated tires
Just went through the same issue and you will wear these stock tires out in no time.
Get D or E rated tires

[WhereStream]

Do they make D- or E-rated tires in this low-profile, 20-inch size?

These tires are entirely new thing to me.

The good ol' Suburban had "tiny" 16-inch tires, which were big for 2004, and in standard balloon profile.

[CapriRacer]

Originally Posted by WhereStream

The tire placard on my new Expedition says to run the rubber at 39 pounds, fore and aft.

These are 20-inch, low-profile tires, which I'm not familiar with.

The low-profile should be good for towing — sidewall less likely to wiggle.

But low profile means low volume of air, so I'm wondering if that means I should do anything special when there's an extra load on the axles.

Retired tire engineer, here. As you have seen, there's a lot of opinions on tires and not all of them are based on facts. So let's start with establishing what are facts and what are opinions:

- You stated that the vehicle tire placard on your new Expedition calls for 39 psi. That doesn't sound right. Would you please check that again and report back? The vehicle tire placard should be on the driver's door post.

Also what year is your Expedition? (2019?) What's the tire size? (Be sure to use the letters in front of and behind the numbers - they are important!)

There is a book called Tire Guides, which lists the tire placard information for all vehicles sold in the US. My latest edition is a 2015, but ALL the Ford Expeditions with P275/55R20's list 35 psi as what is shown on the placard.

What is listed for inflation pressure on the vehicle tire placard includes towing. So if you are towing within the limits published by Ford, the placard pressure is appropriate.

Do some folks prefer different pressures? Sure, they do! But that is their opinion and they are entitled to that opinion.

Also, the tire load tables being referenced in the above posts are MINIMUMS! NOT recommendations. If you do the math, you'll see that Ford specifies MORE pressure than the minimum. (just an FYI, the load tables are published by a tire standardizing organization and the tire manufacturers republish them for informational purposes. In the US, the tire standardizing organization is The Tire and Rim Association - TRA)

It's been said that a tire will wear evenly when it is properly inflated - and that's sort of true, but there is a whole lot missing in that statement.

First, inflation pressure has a small effect on evenness of wear. Other things have a much greater effect - such as whether the tire is in a steer position (shoulder wear), or a drive position (center wear). Or how good the alignment is.

Also, tire manufacturers have spent a lot of research into footprint pressure distribution to minimize the affect load and/or inflation have on wear. (Please note, there are a lot of exceptions to that statement, but that is another discussion.)

And lastly, you stated that low profile tires have low volume of air. Nope, not the case. There is plenty of air - that's how the load carrying capacity is calculated.

So let's start by getting the placard pressure and tire size verified - and go from there.

[WhereStream]

The tires on the Expedition are Hankook (South Korean-made) 285/45 R22 114H.

Judging from appearances, for what that's worth, they are well-built tires.

Max pressure 50 pounds; Ford's recommended pressure, per the door sticker, is, indeed, 39 pounds cold.

[CapriRacer]

WhereStream,

Thanks for that. I am still puzzled by the inflation pressure, because it is non-standard to use 39 psi. Tire Guides does indeed list a 285/45R22 114H for 2015 - at 35 psi. The only way this makes sense is that the 285/45R22 is an XL, where the other tires listed are SL and if I match the load carrying capacity of the SL's at 35 psi, I get 39 psi for a 285/45R22 XL.

Nevertheless, I'll accept that 39 psi is indeed what the placard says and go from there.

To reiterate, if you are towing within the limits specified by Ford, then the pressure on the placard is appropriate. Some people like to use more pressure to reduce sway when towing - and I don't think that is a bad idea so long as you don't go more than 5 psi more.

[Texarado]

Digging up an old thread because I haven’t found anything else on this. I have a 2018 navigator running on the same tires. How am I supposed to calculate whether a 114H is sufficient to tow a FC 25? Any recommendations or help is much appreciated. I’m new to towing and don’t want to be the one on the side of the road.

[CapriRacer]

Originally Posted by jmslade

Digging up an old thread because I haven’t found anything else on this. I have a 2018 navigator running on the same tires. How am I supposed to calculate whether a 114H is sufficient to tow a FC 25? Any recommendations or help is much appreciated. I’m new to towing and don’t want to be the one on the side of the road.

Ford should publish towing specs for your Navigator. Look in the owners manual.

[uncle_bob]

Originally Posted by jmslade

Digging up an old thread because I haven’t found anything else on this. I have a 2018 navigator running on the same tires. How am I supposed to calculate whether a 114H is sufficient to tow a FC 25? Any recommendations or help is much appreciated. I’m new to towing and don’t want to be the one on the side of the road.

Hi

Your Navigator has a sticker on it that shows the maximum axle weights. Divide those in half and you have the minimum tire ratings. Anything over the minimums is fine. If you over inflate for this or that load, you will *eventually* see it in the wear pattern. Few of us are that consistent in loading ( do you go to the CAT scale weekly and adjust inflation ... nope, RV people just don't do it that way ...).

The dealer that told you the tires needed to be rated to handle the entire weight of the trailer was simply not telling you the truth.

Indeed there is tow information on the Navigator, that's being gone over in your other thread.

Bob