Question on Sway and Tires

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Rosspack

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I actually have two questions that I hope others will be able to help me with. Thanks in advance for any help.

#1) My 2015 Expedition has always felt what I would call "loose". There is a lot of play in the steering wheel and it always has felt like it has a little sway. I was wondering if this a probelm in Expeditions or if this is a problem unique to my vehicle. This is particularly concerning when pulling my travel trailer. It is about 8000 lbs loaded and I have the tow package, so I can tow up to 9600 lbs. It in not very stable and has gotten worse, which leads me to question #2.

#2) In orrder to better handle the weight and reduce sway I bought a Pro Pride 3 hitch (sway elimination) and also upgraded to Cooper LT 275/65/R18 ten ply tires. This was at the recommendation of a truck and towing company near me. However, when I took a trip to Jacksonville this weekend the vehicle sway was even worse. It felt like I was pulling the trailer even though I wasn't. There was little wind and I was actually feeling the vehicle move when semis went by like when I am pulling a trailer. The max PSI on these tires if 80. Which is what the place that put the tires on inflated them to. Should I only be running at 80 PSI when I am towing? Does anyone know if there is a recommended tire pressure on 10 ply tires when not hauling with increased weight. It was quite concerning and I white knuckled it most of the way there and back.

Any help would be appreciated, especially regarding the Expedition's stability. Thanks!
 

Meeker

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I'd hazard a guess that there's an issue with your suspension and/or steering if it feels loose to you. Worth checking out.

For #2, I bought similar tires (Michelin AT/2 LTX, same size), but I was able to find a load chart on their website. Those tires are way over-capacity for your truck, so you should find a similar capacity chart which tells you the minimum psi for a given load. The max payload of my truck requires only 44 psi on my tires so I run them at that, but I inflate to 55 psi for towing to reduce sway. No way do you need 80 psi on those.
 

Calidad

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Doesn’t matter what tow vehicle you use you always need to bump psi in rear tires based on load weights. Over inflation definitely creates twitchy driving experience. Under inflation especially with shorter wheel base length vehicles definitely contributes to sway tendencies. Any Jeep guy will tell you they bump rear psi even when just loaded heavy for a camping trip given the short jeeps definitely getting wagging even without a trailer.

How much psi bump is unique to your setup and weight. But if your running stock sized and load rated tires and your general passenger weight door card is say just for example 45psi it’s typical to bump the rears 2-8psi for light ish hitch or rear hatch packed stuff. If your really heavy getting up into the 10-12 psi bump might be needed. But I have never ever seen a within load capacity vehicle need a 20-40psi bump for added load weights when on stock sized and load rated tires.

If you go up tire sizes and change to a different load type tire then you need to start with the load weight vs psi chart for that tire and observe how the tire is wearing at various psi amounts and fine tune it so your seeing even wear across the tire tread.

Wearing down the middle is over inflated

Wearing down the shoulders is under inflated
 

JasonH

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I run my Cooper AT3 at 65 psi when towing my 7k camper and it is very stable. The first thing you should do is visit a scale and make sure your loads are distributed correctly between the Expedition and camper. Once you confirm that, you can check for mechanical issues, like worn bushings.
 

guspech750

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What I did to make my Expy tow very comfortably. I can easily pull 80mph one hand steering comfortably. Obviously extremely windy a days are a bit challenging. I tow with load range E tires. I inflate them to their max 80psi. I want those sidewalls as stiff as they are capable of being. When I’m not towing. I have them inflated to 55psi. I also installed sumo springs front and rear along with helwig sway bars. Soon after we bought our trailer I junked the new OEM tires on our trailer. I replaced them with a higher load range (stiffer walled) Goodyear Endurance. I use the Equalizer 1,000/10,000lb WDH. I’ve fine tuned over the last two seasons.

Check out a scale and see what your weights are. That will give you a better understanding of what is where.
 

Dr0idattack

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I had similar white knuckle driving with a 2013 (no loose steering wheel though.) I went with sumo springs back, Bilsteins all around (4600s I think), LT tires around 80psi, and an Equalizer hitch, and now I can tow pretty fast (although you can still feel it during windy situations that would impact just the tow vehicle itself.)

Like other recommendations, make sure trailer is balanced, and hitch is set right to ensure good weight distribution. Also make sure there are decent tires on the trailer.
 

chuck s

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55 or 60 psi in the Cooper truck tires will handle the GVWR of an Expedition. No need for more pressure towing or not towing. No need for truck tires either but that ship has sailed. Unless the WDH puts weight back on the front, steering axle the truck will be squirrelly.

And the Expedition can't tow a 9600 or even 9200 pound trailer unless it's empty. Every pound in the truck reduces the maximum towing capacity pound for pound. With a cargo capacity of about 1425 pounds putting 1000 pounds on the ball -- 10% is required for safe towing -- there's little capacity left for passengers and dogs.

-- Chuck
 

Fasttimes

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You must learn to use a CAT scale and take the set up when loaded for a trip. I'm pretty sure you're going to find your issues there. As mentioned above, get the suspension checked out. See how old the current springs/shocks are and consider replacing with new if they are old. Then I would add sumo spacers to the rear and upgrade to helwig front and rear sway bars. Then back to hitting the CAT scale to dial in. Look up using CAT scale, 3-way pass to learn.

And I'm pretty sure there never was a 9600 pound tow capacity, it was 9300 for 4x2 and 9200 for 4x4. Pulling 8000lbs is really testing the limits for an Expedition so you really need to beef up the suspension and get it dialed in at a scale.
 

Pawpaw

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Our Cougar can gross out at 8800 lbs. Just wife and I so we load light and try to keep it under 8K pounds. Camper is heavy on the hitch and can get scary in high sidewinds. Payload is 1769 lbs and using a Equalizer WDH. Have 10 ply BFG KO2's and run them at 60 lbs when towing. I tow in the 60 to 62 mph range for better control over the rig. Any long trips I'll borrow son in laws F250 diesel!!
 
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