I apologize in advance, I am going to throw a lot of info out at once for a pretty short question... So My wife and I upgraded from an 18 ft. travel trailer to a 26 ft. Fun Finder 265 RBSS. I have a GMC Sierra 2007 extended cab with the 3.73 rear end and we are using a hitch system with a separate sway bar and the weight distribution bars are rated at 800#. The roads getting to the expressway around our house are a little rough, and I have noticed some "porpising" while towing. On the expressway I have also noticed a slight wag in the rear of the trailer from what I am seeing in my side mirror. It is never severe and always corrects itself. There have been some windy trips home that were a bit white knuckle though. The dealer setup the hitch and the guy said that he got it pretty level and was happy with it. He marked the chain link I should be using. Based on what I have read, it sounds like there might not be enough tension on my bars. My main question is though should I be messing around taking in a link when the guy that does this every day said to use the one link?Some more info: I got new tires last fall. There was a mixup and the tire place and they ended up giving me Load Class E tires. I was okay with that. I have been running them at 45psi which is what the truck calls for. They are rated up to 80 though I think, should I be running them higher? Weight of the gear and people in the truck is right around 700#. Dry weight of the trailer is 5700# and most of my gear is in the front storage under the bed at the tongue. It does have a rear kitchen though and an outdoor kitchen so I know the fridges are adding some weight back there. Fresh water tank is over the axels and while I occasionally pull with water in there I never pull with the gray or black tanks full.Thanks in advance.

If the hitch was set up with the trailer being empty it can make a difference, they really should set it up when the trailer is normally loaded. Setting one link more could make a difference and shouldn't hurt to try it. The perfect setup is to have everything sitting level, the front and rear tow vehicle squat should be almost equal, and the hitch bars parallel with the trailer frame.Your tire pressure probably should be increased above what the truck's door sticker says due to the tire upgrade. What it should be I can't say.

Thanks for the reply. I was a little concerned because I know adding too much tension can cause issues at the front of the tow vehicle. We have a trip coming up this weekend that is going to be mostly expressway driving so I am hoping to find some resolution just for peace of mind and my blood pressure sake. I know the (relatively) high winds we have been getting in MI haven't helped. Our last trailer was only about 3400# dry weight so having to play with the WD bars was never much of an issue.

1) With the trailer not connected measure the distance vertically from the top of your truck front tire OR the center of your truck front hub to the bottom of the fender. 2) Connect the TT to your vehicle. 3) Adjust the chains to restore measurement taken in step 1Without the chains connected you will notice the measurement in step 1 has increased. The trailer hitch weight lowered the trucks rear and raised the trucks front. To put it simply, the chains are to bring measurement in step 1 to it's original height.Air up your tires to at least 65psi. Assure TT is level or slightly nose down. You do not want the trailer hitch higher than the trailer bumper.

I would agree. When our son got his trailer the dealer set up everything so the truck sat level. Once they had it loaded for camping it handled poorly and no longer sat level. We adjusted the bars to a stiffer setting and it handles much better now. If adjusting the hitch doesn't work another option that may reduce porpoising is to add air bags to your truck.

Not knowing what hitch you have This may helpOr This

Weight Distribution Hitch Adjustment Question | Good Sam Community

rrupert
Explorer
Jun 20, 2017
If the hitch was set up with the trailer being empty it can make a difference, they really should set it up when the trailer is normally loaded. Setting one link more could make a difference and shouldn't hurt to try it. The perfect setup is to have everything sitting level, the front and rear tow vehicle squat should be almost equal, and the hitch bars parallel with the trailer frame.
Your tire pressure probably should be increased above what the truck's door sticker says due to the tire upgrade. What it should be I can't say.
bosworthj
Explorer
Jun 20, 2017
Thanks for the reply. I was a little concerned because I know adding too much tension can cause issues at the front of the tow vehicle. We have a trip coming up this weekend that is going to be mostly expressway driving so I am hoping to find some resolution just for peace of mind and my blood pressure sake. I know the (relatively) high winds we have been getting in MI haven't helped. Our last trailer was only about 3400# dry weight so having to play with the WD bars was never much of an issue.
2112
Explorer II
Jun 20, 2017
1) With the trailer not connected measure the distance vertically from the top of your truck front tire OR the center of your truck front hub to the bottom of the fender.
2) Connect the TT to your vehicle.
3) Adjust the chains to restore measurement taken in step 1

Without the chains connected you will notice the measurement in step 1 has increased. The trailer hitch weight lowered the trucks rear and raised the trucks front. To put it simply, the chains are to bring measurement in step 1 to it's original height.

Air up your tires to at least 65psi.

Assure TT is level or slightly nose down. You do not want the trailer hitch higher than the trailer bumper.
grampscamper
Explorer
Jun 20, 2017
I would agree. When our son got his trailer the dealer set up everything so the truck sat level. Once they had it loaded for camping it handled poorly and no longer sat level. We adjusted the bars to a stiffer setting and it handles much better now. If adjusting the hitch doesn't work another option that may reduce porpoising is to add air bags to your truck.
2112
Explorer II
Jun 20, 2017
Not knowing what hitch you have This may help
Or This
DutchmenSport
Explorer
Jun 20, 2017
Just because the dealer set up the hitch for you does not mean you cannot still experiment with it. The next time you tow, shorten the chains by one link and see if that helps performance. If it does, then the next time you tow, shorten one more. If that makes it better, all is well. If not, take it back down one link.

Just because the rig looks level, might not necessarily be the best "sweet spot" for actual towing. Make small adjustments. And if it doesn't feel right within the first mile, you'll know it immediately! Pull over into the first parking lot you find, and set it back to the previous setting. You'll find what works best for your rig.

Now, if after attempting several changes and there is no improvement anywhere, then you need to start thinking about switching something. That may mean a new hitch system, or it might mean a different tow vehicle. But hopefully, it won't come to that.

Nothing is cast in stone just because the dealer said so.
jmtandem
Explorer II
Jun 20, 2017
I apologize in advance, I am going to throw a lot of info out at once for a pretty short question... So My wife and I upgraded from an 18 ft. travel trailer to a 26 ft. Fun Finder 265 RBSS. I have a GMC Sierra 2007 extended cab with the 3.73 rear end and we are using a hitch system with a separate sway bar and the weight distribution bars are rated at 800#. The roads getting to the expressway around our house are a little rough, and I have noticed some "porpising" while towing. On the expressway I have also noticed a slight wag in the rear of the trailer from what I am seeing in my side mirror. It is never severe and always corrects itself. There have been some windy trips home that were a bit white knuckle though. The dealer setup the hitch and the guy said that he got it pretty level and was happy with it. He marked the chain link I should be using. Based on what I have read, it sounds like there might not be enough tension on my bars. My main question is though should I be messing around taking in a link when the guy that does this every day said to use the one link?

Some more info: I got new tires last fall. There was a mixup and the tire place and they ended up giving me Load Class E tires. I was okay with that. I have been running them at 45psi which is what the truck calls for. They are rated up to 80 though I think, should I be running them higher? Weight of the gear and people in the truck is right around 700#. Dry weight of the trailer is 5700# and most of my gear is in the front storage under the bed at the tongue. It does have a rear kitchen though and an outdoor kitchen so I know the fridges are adding some weight back there. Fresh water tank is over the axels and while I occasionally pull with water in there I never pull with the gray or black tanks full.

Thanks in advance.

Air the E range tires to more than 45 psi. Try around 60 or so and see if that helps. As to the dealer hitch set up, if the tow vehicle and trailer was not loaded for camping, the dealer's set up is flawed. Most of the time dealers set up a hitch with the trailer essentially empty and nothing in the tow vehicle. That would be an incorrect set up when fully loaded for camping. Be sure you have ten percent of the trailer's total weight on the tongue and 13 percent would be better.
Turtle_n_Peeps
Explorer
Jun 20, 2017
#1. If you have OEM shocks on your truck take them off and throw them away. They are junk. Put some Bilstiens on it. That will help a bunch with the porpoising.

#2. Rear kitchens "can" be a problem if the trailer is not designed correctly. Even then, they can be a problem if you load a lot of can goods and heavy stuff back there. Do you know what your "exact" packed and ready to go camping tongue weight is? If not, you should because it's important.

#3. You can play with the link count. Nothing is going to blow up if you do. Add one or take one away and go for a drive and see what it does. Give it a try.

#4. Add more weight to the tongue. Pack different or whatever you have to do to get more weight up front. You will have a better handling package if you do. If you have too much squat you can always grab another link and jack it up front.

#5. The more links you grab the harsher the ride will be to an extent.
BenK
Explorer
Jun 20, 2017
What WD Hitch system do you have?

Additional comments embedded below in red

bosworthj wrote:
I apologize in advance, I am going to throw a lot of info out at once for a pretty short question... So My wife and I upgraded from an 18 ft. travel trailer to a 26 ft. Fun Finder 265 RBSS. I have a GMC Sierra 2007 extended cab with the 3.73 rear end

Looked up your profile and it is a half ton....but there can be over a dozen different 'half ton' trucks offered by GM/GMC Best to list its GVWR & both GAWR, along with the GCWR in order for us to help you

and we are using a hitch system with a separate sway bar and the weight distribution bars are rated at 800#.

Without knowing the actual weight of the trailer tongue...800 lbs is out of context. See below need to know your actual tongue weight

The roads getting to the expressway around our house are a little rough, and I have noticed some "porpising" while towing. On the expressway I have also noticed a slight wag in the rear of the trailer from what I am seeing in my side mirror. It is never severe and always corrects itself. There have been some windy trips home that were a bit white knuckle though. The dealer setup the hitch and the guy said that he got it pretty level and was happy with it. He marked the chain link I should be using. Based on what I have read, it sounds like there might not be enough tension on my bars. My main question is though should I be messing around taking in a link when the guy that does this every day said to use the one link?

do not fixate on the dials/knobs/etc....all they are, are adjustments to to goal when finished adjustments. Have seen advisors run newbies in circles dialing in something that worked for 'them' and on that, just about every setup is different and there is no one size fits all...other than the goal for the final setup

That there is enough tongue weight (should be in the 12%-15% of the trailers ACTUAL weight).

That the trailer is level at it's highest pointing and IMHO prefer pointing slightly down

That you are within your OEM's ratings...assume you believe in them. If not, then academic this discussion. If yes, then gather your OEM's ratings info...go out and actually weigh the whole setup, axle by axle.

Then plug that actual info into the generic formula GCWR >= TV + Trailer + stuff.

Some more info: I got new tires last fall. There was a mixup and the tire place and they ended up giving me Load Class E tires. I was okay with that. I have been running them at 45psi which is what the truck calls for. They are rated up to 80 though I think, should I be running them higher?

Again, goes back to 'which half ton' you have. The higher rated GVWR will come from the factory with the next higher class tires that you now have. Regular half ton's come with passenager class tires (noted by a 'P' and you now have 'LT' or light truck tires)

The door label will list a tire class and size...that PSI info is for that tire. You no longer have 'that tire', but the next higher class tire and you have to figure out what PSI is best for you

LT class, load range E should NOT be run below 45PSI, IMHO. Unless they are flotation tires, which max out at 35PSI.

Weight of the gear and people in the truck is right around 700#. Dry weight of the trailer is 5700# and most of my gear is in the front storage under the bed at the tongue. It does have a rear kitchen though and an outdoor kitchen so I know the fridges are adding some weight back there. Fresh water tank is over the axels and while I occasionally pull with water in there I never pull with the gray or black tanks full.

Thanks in advance.
Hannibal
Explorer
Jun 21, 2017
bosworthj wrote:
The roads getting to the expressway around our house are a little rough, and I have noticed some "porpising" while towing.

When the road is rough, especially concrete interstate, porpoising is unavoidable with a heavy trailer. We just ride with it. As long as it's not porpoising on level highway.

bosworthj wrote:
On the expressway I have also noticed a slight wag in the rear of the trailer from what I am seeing in my side mirror. It is never severe and always corrects itself. There have been some windy trips home that were a bit white knuckle though.

Is this wag constant or only with a gust of wind or passing truck? Box trucks are worse than 18 wheelers in my experience. Ours will wag on occasion and straighten out on it's own. This is normal. We've caravanned with others using sway control hitches and we could see their trailers wag as much as ours with no sway control in strong cross winds. They may have felt it less with sway control. I saw our 32' 5th wheel wag in the wind through my side view mirrors but never felt it in the truck. On one trip out I-10 in the Florida panhandle, the strong crosswind and constant passing trucks called for constant corrections on the steering wheel of about 2" either way. It was annoying but not scary. The first time I felt this with our first TT in '94, it was scary. Now I'm used to it and it's just part of towing a TT for me.

bosworthj wrote:
The dealer setup the hitch and the guy said that he got it pretty level and was happy with it. He marked the chain link I should be using. Based on what I have read, it sounds like there might not be enough tension on my bars. My main question is though should I be messing around taking in a link when the guy that does this every day said to use the one link?

If the truck and trailer sit level together and it tows well when no other influences are pushing it around or bouncing, I'd have to believe it's set up correctly. Our TT settles the rear of the truck 2" and the WDH brings it back up 1". This works well for us.

bosworthj wrote:
Some more info: I got new tires last fall. There was a mixup and the tire place and they ended up giving me Load Class E tires. I was okay with that. I have been running them at 45psi which is what the truck calls for. They are rated up to 80 though I think, should I be running them higher? Weight of the gear and people in the truck is right around 700#. Dry weight of the trailer is 5700# and most of my gear is in the front storage under the bed at the tongue. It does have a rear kitchen though and an outdoor kitchen so I know the fridges are adding some weight back there. Fresh water tank is over the axels and while I occasionally pull with water in there I never pull with the gray or black tanks full.

Thanks in advance.

New tires will have some tread squirm until they wear in a little. My new Firestone TransForce HT's were pretty squirmy for the first 2k~ miles. I agree with above. Air them up to 60psi and see how it feels.
I'm not a big fan of rear kitchens for the reason you stated. Load as much as you can in front of the axles to compensate. Even with proper loading, you still have a lot of weight aft of the trailer axles.
If you're using a single friction bar and feel like you need more, I would recommend an Equalizer or Reese DC hitch. Just my humble $.02.