sway

Sorry for the long post--I get excited by trailer setup!
My experience and opinion—yours will vary. Lots of good posts above, some of which I will slightly repeat for emphasis.
We towed for 7 years with an F-150. Small 4.6 V8, 4 wheeler in the bed, towing a trailer likely over 6400 lb. Never felt a bit of sway, but a bunch of bow wave. Used P XL extended load range tires aired up to the tire rating of 43 psi (not the sticker guidance of 35 psi), 800 lb. WD and double friction sway control.
1. First be sure that it is not just the bow wave that is being noticed. When 2 boxes pass or meet at highway speed (and you’re pulling a bumper hitch trailer), the bow wave will push the tow vehicle steering back and forth. A slight steering wheel tightening, first one way then the other, will be necessary to correct to straight down the road driving. This is normal. Fifth wheels and goosenecks don’t exhibit this because their hitch point is at the axle.
2. Sway is an out of control push often turning into an oscillation as the driver tries to correct, resulting in a collision if not quickly brought under control. Ford sway control is an emergency feature that kicks in AFTER sway is detected by the vehicle stabilization system. It does nothing to prevent sway, which is all about tow and trailer setup. Hopefully, it detects sway at a low enough level to avoid the collision, but you still don’t want it to ever kick in.
3. I am a HUGE believer that proper front axle weight is important to preventing sway. Easiest way to check this (and maybe more accurate than wheel well measuring) is just to mark a spot on the front bumper and measure to the closest ground point to the nearest 1/16”. You want to return the height loaded with WD back down close to the distance sitting unhitched which will confirm that the original weight is back on the front axle. You can’t move the truck while doing measurements and maintain accuracy using the bumper method. Ford guidance is to shoot for ½ of the distance between unhitched and hitched with no WD. I have always tried for 1/8 to ¼ inch up which should be very close to returning the unloaded weight back to the front axle. The WD setup for our first trailer done by the dealer was adjusted for rear squat—WRONG! It resulted in too little rear axle weight and spinning tires. Probably also too much front axle weight. Do not trust the dealer—they’re in a hurry for the next sale.
4. It is possible to have too much weight on a bumper hitch. My son hooked up a pole trailer to his F-350 dually, crew cab, long bed truck and loaded the trailer front heavy to make sure he had enough tongue weight. Out on the road at highway speed, sway shoved his truck right to left on a 3 lane interstate. He got it settled down and then sway pushed the truck back across the 3 lanes to the right. We believe that too little front axle weight was a large contributing factor. It was so scary that he started using WD and anti-sway on his 6000 lb. camping trailer.
5. If OP has any possibility of upgrading to a fifth wheel in the future, the 2021 solution should be a 350/3500 truck for adequate weight ratings for the heavier pin weights. Yes, the price difference is large for the little bit of equipment that changes, but the weight sticker will keep you out of trouble. Be sure to check licensing and insurance costs in your state as part of the decision.
6. IMHO the only thing air bags help with is rear swat with inadequate springs. OP says he is sitting level so likely not needed.
7. Ideally the trailer should be level to slightly nose down. If an adjustment is needed, then the only adjustment for that is changing the position on the shank bar, buying a different bar if needed. WD needs to be set up first and will need to be rechecked after a shank bar move.

make sure its level and has enough tongue weight. tow with tanks empty and around 15+ percent tongue weight. use proper sway control, look forward to the 3/4 ton truck you will be getting soon

Nothing back from the OP ?

I will say this, My daughter and future Son In Law have a set up almost identical except their stock tires are GY and sticker says air to 35#.. They are at the upper end of their capacity and I told them when towing, go to max listed on sidewall, which is 51#..

Their plan WAS to get married in June, ( didnt happen, thanks COVID ) move into their house ( that did happen ) and buy a new truck in the fall.

They have little sway, The sway they have I believe is from the fact that it is a rear kitchen with a good bit of the weight BEHIND the TT axles.

FWIW - If OP doesn't do his/her own maintenance, that can also be an issue with tires. Your typical oil change shop has been known to simply look at the door sticker and adjust pressure without paying attention to the actual rating of the tire. As noted above, an under-inflated tire can most certainly be a problem!

All conjecture aside, everyone think back to what makes a HD truck “handle” a trailer better than a 1/2 ton. I don’t mean more power to pull it easier, I mean handling the weight and push pull of the trailer.
It’s TV weight, stiff suspension and stiff tires.
If you can accomplish 2 of the 3, IE tires and suspension, it will be markedly better than soft tires and soft suspension.
Even aired up, way up, P or XL tires aren’t as stiff as LT tires.
I run 44psi rated tires at 50-60psi when the load capacity is needed on my little half ton.
It helps tremendously in controlling the trailer as well, however they’re still A bit softer and roll over more than a comparable E tire at 60 psi.

In 30 years of driving/owning/ towing with 100s of different combinations. Most not “calculated”. It’s construction. No one is spending hours setting up their truck If trailer needs to get from A to B NOW. I’ve never seen a single downside to E tires on a half ton. None. Adjust pressure to your load/preference and go. Far more adjustability and capability with “too much” tire.

LT E tires on a std duty 1/2 ton truck need more than 35 psi as most stickers say.
As mentioned this can and has caused tread squirm leading to sway issues.
Also those big new LT E tires tread is usually thicker when new than a P tire can aslo show tread squirm leading to issues with swaying.
It can take several thousand miles to get the tire broke in and eliminate tread squirm.

I'm not a fan of LT E on std duty 1/2 ton trucks. BTDT and always went back to a good P tire.
I pull a 10k car hauler with 8600-9400 lb on the trailers axles/blue tractor with a cab... with the wifes 2016 1500 chevy 4wd and P265-70-17 tires pumped the rears to max 44 psi. Ran the OEM set of tires for 46k miles and now around 12k on the second set. No sway issues at all.

Play around with psi in those LT E on the rear and see what works better.

Dear OP.
The last half dozen or so responses talking about how E load tires aren’t appropriate for a half ton and how they need more pressure than a softer P tire for the same load, are largely about 112% completely false and I actually wonder where some folks get these crazy theories.....
And a lot of 1/2 tons come shoed with XL rated tires which are like P+ rating. But heavier than P but not as stout as a D load tire.
Carry on.

You REALLY should stick to the MANUFACTURERS OEM tire size and style choices.. If you want to move from P to LT tires, choose wisely and don't over choose, a "C" load rating would have well exceeded a 1/2 ton capability by around 1,000 lbs on the axle and it would have done that with 45 PSI.. The E load rated will most likely need around 60-65 PSI to be near the "C" load rating..

I'll have to disagree with you, p rated tires are good for like shopping and light use. LT tires are much better suited for towing, or hauling stuff and will give less feel of sidewall roll when towing. Tbh ,I think 1/2 ton trucks should come with LT tires on them. Not nessassarly e load but something better then p tires. You kind of eluded to that in the post. But to say stick to the crappy oem p tires isnt great advice.

afidel wrote:
Who follows the door sticker for tire inflation, especially for non-OEM tires? I put in the max cold PSI indicated on the sidewall.

OP HAS "E" load rated tires.

What do you not understand about that?

E load rated tires have a side wall pressure of 80 PSI which is most likely well above the rim pressure rating.

Those tires have a load rating well over 3000 lbs at the sidewall pressure of 80 PSI.

Those tires BELONG on a F250/350, not on a F150.

That combo is not going to work well at full sidewall pressure and most likely will become a lot more unhinged.

For some odd reason folks seem to believe moving to the heaviest LT tires are the fix to everything, it is not, this is the case where doing so can and will make things far worse.

You cannot ever make a 1/2 truck into a 3/4 or 1 ton truck by simply switching tires. It takes a whole bunch of OTHER parts and even then in the end you STILL have a truck that legally is a 1/2 ton truck.

You REALLY should stick to the MANUFACTURERS OEM tire size and style choices.. If you want to move from P to LT tires, choose wisely and don't over choose, a "C" load rating would have well exceeded a 1/2 ton capability by around 1,000 lbs on the axle and it would have done that with 45 PSI.. The E load rated will most likely need around 60-65 PSI to be near the "C" load rating..

Should be illegal for tire shops to sell E load rated LT tires to 1/2 truck owners.

Heavier tire is not "always" better.

All I can say is another "amateur day" rookie mistake :E ..

Someone that does not know about increasing the tire pressure for E capacity tires may look at the door sticker. Gdetrailer was just being helpful. I also run near max pressure for my LT tire on my F150. I checked the manufacturer's site and run the psi that is suggested for my wight.