When we are driving down the highway towing our new travel trailer, at times it feels like there is a slight "tug" coming from the back/trailer. It is not constant, and does not seem to be any one particular type of road surface. Most of the time it runs smooth or smooth enough, but an occasional block of time where you feel this "tug" while towing is not unusual. The trailer brakes don't seem to be hot when I check them, so I don't have any clue as to why this sometimes happens.

We just stepped up in size from an Escape 21 travel trailer (gross wt about 4500 lbs) to a Bigfoot 25 travel trailer (gross wt about 7500 lbs), both dual axle with trailer brakes. We never had any issues towing the Escape 21. We loaded the truck and then the trailer up with our stuff, I took it to the local CAT scales and did the two weigh-ins. Everything seems to calculate out within limits and we seem to be okay on total weight and tongue weight. We use a Blue-Ox WDH and set it between 7 to 9 links, usually 8 but have used all three, this issue happens with any link setting.

Here are my CAT scale weights:

Weight 1 (w/o Trailer, in Lbs):
Steer Axle 3320
Drive Axle 2960
Trailer Axle 0
Gross Weight 6280

Weight 2 (w/Trailer attached, in Lbs):
Steer Axle 3160
Drive Axle 3920
Trailer Axle 5700
Gross Weight 12780

When we towed our Escape 21 you could hardly tell it was there. I'd hate to think that I messed up my tow capacity calculations, but I went over the numbers several times and they seem to be okay. I hate to be the guy towing a disaster down the highway, so any thoughts/suggestions as to how to diagnose this or what actually might be causing this occasional tugging feel?

 

Does the new trailer have more of the front cap sticking up over your tow vehicle? Thinking head wind.

 

For me, I feel a bit of tugging on what seems like 'concrete' hwys. They just have different dynamics than blacktop stretches. Could that be your sensation? I think the extra size and weights, different dynamics, you might need to just give it some more time? That is a whole lot of trailer, not saying excessive, certainly would be my upper end on my 2020 short bed maxtow with similar payload. I will say, my towing dynamics improved with better shocks, and tires on both truck and trailer. Do you have a picture of loaded combination, standing back a ways, flat parking lot? sometimes squat, or nose high trailer effects dynamics a lot.

 

I agree that the new trailer could be catching more air than the old one and that is adding to the tugging feeling.

You said above “We loaded the truck and then the trailer up with our stuff, I took it to the local CAT scales and did the two weigh-ins. Everything seems to calculate out within limits and we seem to be okay on total weight and tongue weight.”. You may want to have a second look at those numbers……….
Loaded up your truck is over it’s GVWR of 7050 at 7080 (3320 front + 3920 rear) so (+30).
Over the rear GAWR of 3800 at 3920 (+120).
Hitch rating of 1100 at 1120 (+20).
Nothing horrible, but it is over on those ratings, so you are pretty much at the practicle limits of the trucks TT towing ratings. Given those numbers I would increase the load on the WD hitch spring bars some. This should move some of the high rear axle weight to both the front axle which has some room and the trailer axles as it takes some weight off the heavy rear axle. With the right amount of adjustment there you could get the rear axle back under its rating and have the GVWR back under the rating also. And it may also tow a little better with more WD loaded.
The trailer weighs 6820lbs.

 

Trailers are going to tug or jolt sometimes. Might still happen when you inevitably upgrade trucks. I hate maxxing out my ratings. Bad mojo on any truck.

Id have to drive it to see if its excessive or not. See if you can remove weight from the rear of your trailer. Add to front of trailer, or bed of truck. If that overloads the truck even worse, upgrade to a 350.


Does the truck bounce or porpoise?

 

The trucks anti-sway uses the brakes, so it's possible it could be pulsing your brakes for a moment and that's the "tug" you are feeling. Hard to diagnose these things over the internet, but something in the brakes, suspension, or sway systems is probably the culprit here.

 

Going to agree with @WE3ZS on this one, you're right at the max capabilities of the truck as far as ratings go. Some adjustment is needed on the WDH to get that rear axle back under its gross rating, but even then you're still at the max that truck can handle.

That 'tugging' feeling could be any number of things, from your truck's 'anti-sway' trying to correct sway that may not be there, to this bigger trailer giving your truck a harder time pulling (larger/heavier, more wind resistance, being slightly tongue-heavy, etc). Without driving it I can't really diagnose it.

If, after you adjust your WDH to get that rear axle back under its gross rating, it's still giving you fits...you might need a bigger truck for that trailer. Looks like you've got an F150 with a gross rating of just over 7k lbs, there are models optioned to handle heavier weights but may not have amenities you are currently enjoying, so you COULD stay with an F150 with a higher payload/tow rating. Or you could step up to an F250, which just about immediately does a better job.

 

Agree with adjusting the WDH to get more weight on the front axle. Another link or two on the hitch might get you there. This will also help with getting the rear axle weight back under it's rating.

Curious what all you had with you when you weighed the truck alone. Your payload sticker indicates that your truck should weigh about 5100 lbs, but you were well over 6000 lbs. What did you have in the truck that soaked up the extra payload? Is it possible to relocate that extra 1000 lbs to the trailer? that would help with your GVW and GAWR on the truck if you can.

As to being at the max for the truck, i'd disagree. You are only at the max now because of your payload. You literally can't tow anything bigger because of your payload capacity on the truck (see above about relocating the extra 1,000 lbs of stuff). But above that, your camper is only 6500 lbs. You are well with in the realm of reasonable for a capable half ton truck like yours.

The tugging is likely wind gusts. with that much frontal area it doesn't take much of a gust to feel it and make it feel like you are hitting the brakes, at least in my experience anyway. its possible that the TCS and RSC are tapping the brakes for you, but i've never had that happen (and i've towed in some really treacherous winds). I hear that its a thing, but i haven't found the limits that will activate my RSC. But, with all of that said, turn them off and see if it makes a difference. Check the brakes on the truck, if one or two of them are much hotter than the others, then that could be due to the TCS/RSC activating one wheel (or more) due to perceived sway.

my take is that you are towing a sail and you are feeling that sail catch the wind. from what i can gather your new camper is a foot wider and a bit taller as well, it is going to catch more wind than the old one. wind resistance is exponential, so a little change makes a big difference.