Sway problems

[Wscott52]

2015 F250 crew cab short bed 4x4 diesel -8650lbs (front 4900,back 3750)
35”x 12.50 x 18 (12 ply toyo)
2016 keystone impact toyhauler - 10,600lbs loaded, 1550 tongue weight

Curt WDH 17501 series with bars not chains

Level lot unhooked truck- front fender 42 1/2. Rear fender 43 1/2
Level lot hooked no wdh- front fender43 1/2. Rear fender 41 1/2
Level lot WDH front fender 42 1/2. Rear fender 42

Ball on unhooked truck is 26” to top of ball
Trailer top of hitch 24 1/2

Whew. I think i have given you all the details.
My problem is sway over 50 mph, i have read and researched all that i can. I have spent hours in a parking lot with no success. I am so frustrated right now i can scream. This is my 5th camper so I’m not new to this. I own and drive semi trucks so I’m not new to towing.
Comes a point where i need your expertise please.
Thank you in advance!!
Wscott

[ppine]

Add a sway bar for $100.

[Terryallan]

carringb wrote:
Also - I just re-read the numbers in the original post. It looks like you're fully restoring front axle height. On heavy pickups, this can leave the rear axle too light. Might want to take a out a washer or two, to slightly reduce how much weight is being moved to the front axle.

his rear axle is still dropping an inch and a half. so it has plenty of weight on it.

[librty02]

Sweet!!
Now just make sure those trailer kings are rated for speeds above 65mph most that I know of are not so watch going that 72 with 1 finger on the wheel. I have the Carlisle Radial HD's that are rated for 81mph and in the 3 years I have had them now have been great tires.

[Wscott52]

[Wscott52]

OK
Just returned from a 40 min hwy test run.
Truck tires @ 60 psi
Trailer tires up to 80 psi
Adjusted the WDH to allow for 1/4 rake nose down on trailer.
Drum roll .................

Boo ya. Cruise at 72 one finger on steering wheel. Flip flop is gone!
Squishy trailer tires appear to be the issue, in looking for the problem i appear to have skipped the smallest detail and had gone straight to all the big issues.

I would post a pic but can’t figure that one out right now.
I want to thank each of you for your input, it helped me out of my tunnel vision.
Sincerely
Wscott

[Grit_dog]

In my experience, I've seen 4 primary causes of trailer sway.
1. downhill and trailer is pushing the truck, but this is downhill only and exaggerated by other less than ideal conditions.
2. Soft trailer tires.
3. Not enough tongue weight. (Doesn't appear to be the case here)
4. GROSSLY overloaded tongue weight on the truck (not the case here).
Certainly there are other nuances that affect sway too but I think these are the more typical ones.
(Like axles too centered on trailer, enough tongue weight, but a disproportionate amount of load behind the trailer axles will make the tail wag the dog.)


OP, agree 50psi in the trailer tires sounds very low and squishy trailer tires will cause or exaggerate sway.
Presuming your 80psi tires are 15" on 5200lb axles (just a guess unless your trailer is overbuilt), you should be near max pressure for the load.
Also, have you tried towing without the wdh or taking most of the weight distribution out of it to eliminate that variable?

Agree, that tongue weight and truck setup should tow fine.

[Grit_dog]

twodownzero wrote:
Wow, this one is all over the place. Do not drop your truck's tire pressure to 55, especially on the rear axle. That is dangerous.

It sounds to me like you simply don't have enough tongue weight. Load it heavier. The sway will go away with enough tongue weight. Trying to look for other solutions might work, but adding tongue weight is sure to work.

Dangerous at 55psi? how?
OP says 1550lb tongue weight, so from the info given....avg big truck = 3000-3500lb empty rear axle weight + 1550lb tongue weight (which he's actually pulled weight off of with the wdh), so about 5000lbs on the rear axle and what's the tires good for at 55psi? Over 300lbs/tire.
This assertion is contradictory to your next statement of not enough tongue weight. Again OP measured trailer at 10,600 and tongue at 1550lbs. Sounds sufficient doesn't it? How much tongue weight should a 10k bumper pull have?

[carringb]

twodownzero wrote:
Wow, this one is all over the place. Do not drop your truck's tire pressure to 55, especially on the rear axle. That is dangerous.

It sounds to me like you simply don't have enough tongue weight. Load it heavier. The sway will go away with enough tongue weight. Trying to look for other solutions might work, but adding tongue weight is sure to work.

No. It's not dangerous. Too much tire pressure causes instability. That is why every tire manufacturer, including Toyo who makes the OPs tires, publishes load inflation tables. His current tires are nearly 20% wider than stock, so the factory tire pressure are completely irrelevant.

He has 15% tongue weight now, so that is not his problem.

[BenK]

Hi JR !

Nice to meet you

You are the first one here to understand trailer tongue orientation and trailer caster here on this forum !

Take care (system won't allow me to post a PM for some reason)


Ben

JRscooby wrote:
Is the trailer nose high when hooked up? This can change the caster, make the trailer refuse to track. Of course, that would happen at all speeds, but faster would put more side force on the TV...

Wscott52 wrote:
Just bought it 6 weeks ago.
5 hours home .. scary
60 mile away test camping weekend
And this last weekend 120 miles away is all we have done.

You mean the trailer was MT when you had issues?

[Wscott52]

carringb wrote:
Also - I just re-read the numbers in the original post. It looks like you're fully restoring front axle height. On heavy pickups, this can leave the rear axle too light. Might want to take a out a washer or two, to slightly reduce how much weight is being moved to the front axle.

Ok let me do the air pressure test then if that doesn’t solve it i will move to WDH
TY

[twodownzero]

Wow, this one is all over the place. Do not drop your truck's tire pressure to 55, especially on the rear axle. That is dangerous.

It sounds to me like you simply don't have enough tongue weight. Load it heavier. The sway will go away with enough tongue weight. Trying to look for other solutions might work, but adding tongue weight is sure to work.

[Wscott52]

BenK wrote:
As for tire pressure...rim width plays too

Also sidewall aspect ratio

Majority of folks today are opting for higher unsprung weight (metal weighs more than air and rubber) via lower profile & larger dia wheels and that is a good thing for towing....but...8f the rim width is on the narrow end of the tire OEM's recommended range, the the added sidewall bendback negates increased handling ability if lower profile sidewalls

#1 is higher slip angle...a ride quality component to tire performance. A wider rim reduces slip angle to allow more precise steering wheel response.

A narrow rim width has more sidewall bendback, so the tread squirm is increased... while the sidewall's increased "wave" has the wheel pointing one way and the tread points on another track. This also allows more wallowing as they try to realign

Why my rims are 10 inches wide. Sure it rides like a truck (of which it is to me), but steering precision is tops and next to none, and no ride quality (of which I don't care for)

Your lower trailer tire PSI will affect, as there will be a bit more sidewall flexing....that will allow the trailer to both lean more and wallow more as the rim rolls back and forth trying to center themselves on the tread track

IMHO...use the chalk method to check tire pressure vs loading. I also check them often and also look for where the outer tread rib's pavement wear edge is. If it is inward of the tire edge...PSI is to high for your load & driving style...if it is on the sidewall side of the edge...PSI is not high enough for your load & driving style

Please report back on how it goes

All i heard from that was I HAVE TO GET NEW WHEELS
OHH HONEY........
:B

[carringb]

Also - I just re-read the numbers in the original post. It looks like you're fully restoring front axle height. On heavy pickups, this can leave the rear axle too light. Might want to take a out a washer or two, to slightly reduce how much weight is being moved to the front axle.

[BenK]

As for tire pressure...rim width plays too

Also sidewall aspect ratio

Majority of folks today are opting for higher unsprung weight (metal weighs more than air and rubber) via lower profile & larger dia wheels and that is a good thing for towing....but...8f the rim width is on the narrow end of the tire OEM's recommended range, the the added sidewall bendback negates increased handling ability if lower profile sidewalls

#1 is higher slip angle...a ride quality component to tire performance. A wider rim reduces slip angle to allow more precise steering wheel response.

A narrow rim width has more sidewall bendback, so the tread squirm is increased... while the sidewall's increased "wave" has the wheel pointing one way and the tread points on another track. This also allows more wallowing as they try to realign

Why my rims are 10 inches wide. Sure it rides like a truck (of which it is to me), but steering precision is tops and next to none, and no ride quality (of which I don't care for)

Your lower trailer tire PSI will affect, as there will be a bit more sidewall flexing....that will allow the trailer to both lean more and wallow more as the rim rolls back and forth trying to center themselves on the tread track

IMHO...use the chalk method to check tire pressure vs loading. I also check them often and also look for where the outer tread rib's pavement wear edge is. If it is inward of the tire edge...PSI is to high for your load & driving style...if it is on the sidewall side of the edge...PSI is not high enough for your load & driving style

Please report back on how it goes