Eagle HT 24.6 bounces like a ball

[Route 66 Traveler]

Originally Posted by TxLoser

I had 15” Endurance tires on my 2017 HT and it was 80psi on the sticker same at the 16”.

65 psi is molded into the sidewalls of my 15" Endurance tires. I set mine at 60psi according to the Goodyear load table. Show little wear after 3 years and 9000 miles.

[Jack 56]

I have rancho adjustable shocks on my 2011 GMC 2500 HD while towing my 36KPTS they are adjusted to max and while towing. Not towing adjusted to minimum. Seems to work. I experienced bottoming out to the stops on extremely rough roads so I tried sumo overload springs and ended taking them off because they were too stiff. I have been on the stretch of 5 you described and the shocks did their job.

[aplunkett]

Ours is a 2018 Sierra 2500Hd and 2018 339FLQS. I developed the bounce issues at 28,000 miles. Replaced my stock shocks with Bilstein 5100s, and went back to smooth sailing. Stock shocks were trashed.

[jadatis]

I would like to have your exact specifications of trailertires.
Sises and they are ST
Maxload or loadindex
Referencepressure 80 psi we know already.

Then higher weight on rear axle of trailer suspects a to high pin.

If you give those tirespecifications, this " pigheaded Dutch selfdeared tirepressure-specialist" can calculate a pressure for the TT with maximum reserve, with still no bumping.

I dont say the tirepressure must be the cource, but mayby my calculation can exclude it (or make it plausable).

[MtnGoat]

Scales were open yesterday and my numbers look good.
Tires Goodyear Endurance ST225 /75R15E
are rated 2830 lbs at 80PSI each or 11,320x4.


Scale Wts
17260 Total
8320 Truck
8940 RV
1560 Pin Wt

Sticker Wts
7701 RV Empty
2249 RV Cargo
9950 RV Max

[Dave A]

Originally Posted by MtnGoat

Scales were open yesterday and my numbers look good.
Tires Goodyear Endurance ST225 /75R15E
are rated 2830 lbs at 80PSI each or 11,320x4.


Scale Wts
17260 Total
8320 Truck
8940 RV
1560 Pin Wt

Sticker Wts
7701 RV Empty
2249 RV Cargo
9950 RV Max

Your pin weight might be a little light, that box on the back is not helping any. You might try removing the box and shifting some of your cargo more to the front and see what happens. Good Luck!

[MtnGoat]

Originally Posted by Dave A

Your pin weight might be a little light, that box on the back is not helping any. You might try removing the box and shifting some of your cargo more to the front and see what happens. Good Luck!

It was suggested that I fill the fresh water tank. That will add 400 pounds. Im not sure where the tanks are located along the length of the trailer. If I use the dump valves as a general indicator, fresh water is the farthest aft. Bathroom grey water is the closest to the pin.

[gymracer]

As for towing with a 2500HD 4x4, I pull a 8000# trailer with no airbags with ease. Not sure about pin weight as never had a reason. Some of our roads are not so good either. I run the speed limit to not be a holdup to traffic. Bridges are the worse thing we deal with and air pressure, air bags or shocks are not fixing that.

[cadman_ks]

Originally Posted by gymracer

As for towing with a 2500HD 4x4, I pull a 8000# trailer with no airbags with ease. Not sure about pin weight as never had a reason. Some of our roads are not so good either. I run the speed limit to not be a holdup to traffic. Bridges are the worse thing we deal with and air pressure, air bags or shocks are not fixing that.

I agree with everything you said here. Our old truck is a 2500, and we never had any issues pulling with it, UNTIL we were overweight, and that's another problem. A 2500 should have no issues with the OP's unit

As for bridges, I can't agree more. The approaches to most bridges are absolutely terrible. There's a bridge that we have to cross quite often, and if we do t slow down to about 60, there's a good chance that the truck is literally airborne as we cross!!!

[Dave A]

Originally Posted by MtnGoat

It was suggested that I fill the fresh water tank. That will add 400 pounds. Im not sure where the tanks are located along the length of the trailer. If I use the dump valves as a general indicator, fresh water is the farthest aft. Bathroom grey water is the closest to the pin.

If that tank is towards the rear, filling it will probably not be a good idea. You mentioned early it feels like the camper is "rocking" back and forth. If we're thinking the same thing, I still think your weight distribution might be off and some new shocks on the truck sure couldn't hurt either.

[goducks]

Originally Posted by MtnGoat

It was suggested that I fill the fresh water tank. That will add 400 pounds. Im not sure where the tanks are located along the length of the trailer. If I use the dump valves as a general indicator, fresh water is the farthest aft. Bathroom grey water is the closest to the pin.

Where's the fresh tank drain? It should be under the fresh tank. Have you ever drained the fresh tank?
I highly doubt that box is doing harm. It's not a 100% pin reduction because the axles aren't dead center under the 5th wheel.

[Jagiven]

Originally Posted by MtnGoat

Scales were open yesterday and my numbers look good.
Tires Goodyear Endurance ST225 /75R15E
are rated 2830 lbs at 80PSI each or 11,320x4.


Scale Wts
17260 Total
8320 Truck
8940 RV
1560 Pin Wt

Sticker Wts
7701 RV Empty
2249 RV Cargo
9950 RV Max

Originally Posted by Dave A

Your pin weight might be a little light, that box on the back is not helping any. You might try removing the box and shifting some of your cargo more to the front and see what happens. Good Luck!

I agree your pin weight is low. Pin weight on a 5ver should be between 20-25% of the 5vers GVW. Your running about 17.5%.

Scaled weights

20% of 8940 = 1788#
25% of 8940 = 2235#

Ideally I would recommend trying to have your pin weight around 2000#, so if you load differently between different trips you still have enough pin weight.

[jadatis]

Originally Posted by MtnGoat

Scales were open yesterday and my numbers look good.
Tires Goodyear Endurance ST225 /75R15E
are rated 2830 lbs at 80PSI each or 11,320x4.


Scale Wts
17260 Total
8320 Truck
8940 RV
1560 Pin Wt

Sticker Wts
7701 RV Empty
2249 RV Cargo
9950 RV Max

Then I first had to do a little research.
In general I substract 6 loadindex steps from the ST loadindex, would be 117-6 is 111 loadindex, to give tire same deflection a LT would have.
This together wit using 90% of the loadcapacity belonging to the pressure, this gives max reserve without bumping.

But the smaller sises sometimes ST less more maxload then LT with same specifications.

Now this sise is not made in LT., so I googled for 225/70R15 in LT, and found D-load LI 112 so AT 65psi.

If I now look in goodyear list for the Endurance 225/75R15, 80psi gives that 2830 lbs maxload, and 65psi gives 2540lbs maxload., wich is loadindex 113, wich can be explained by /75 and /70 difference.
So for this sise ST they did not use higher maxload then LT, if it existed.

So if LT was made in E-load in 225/75R15, it would also have loadindex 117 / maxload 2830 lbs.

Now thst is solved, I putted in my made traveltrailer tirepressure calculator next
Totalweight 8940 lbs.
Loadindex 117 / maxl 2830 lbs
Reference-pressure 80 psi
4 tires of RV on the road.
Pin 1560lbs is 17. 4%, to my opinion not extremely low.

Gave 57 psi as highest pressure, so maximum reserve for for instance R/L inbalance, without bumping.

So to high tirepressure is a possible cource of your inbalance., or at least plays a part.

Have to look back your given axleloads and calculate the pressure for rear RV of by head 3800 lbs. See what that gives for psi.

Will give that in next post.

[jadatis]

The 3860 lbs on rear axle, with same reserves gives 60 psi, and I would use that for front RV axle too.

But now I will give a pressure loadcapacity list.
For 4 tires/2axles, in front and 2 tires/ 1 axle behind the psi.
Then if weights change you can look up a new pressure but first only substract the weight on pin.
Your RV 8940 - 1560 = 7380 lbs on the 4 tires to look back in the list.

2 axles 4tires /psi/ 1axle 2 tires

4151 lbs/ 30 psi / 2075 lbs /
4399 lbs/ 32 psi / 2199 lbs /
4646 lbs/ 34 psi / 2323 lbs /
4893 lbs/ 36 psi / 2446 lbs /
5139 lbs/ 38 psi / 2569 lbs /
5384 lbs/ 40 psi / 2692 lbs /
5628 lbs/ 42 psi / 2814 lbs /
5872 lbs/ 44 psi / 2936 lbs /
6116 lbs/ 46 psi / 3058 lbs /
6359 lbs/ 48 psi / 3179 lbs /
6601 lbs/ 50 psi / 3300 lbs /
6843 lbs/ 52 psi / 3421 lbs /
7084 lbs/ 54 psi / 3542 lbs /
7325 lbs/ 56 psi / 3662 lbs /
7566 lbs/ 58 psi / 3783 lbs / 7380 on 4 t
7806 lbs/ 60 psi / 3903 lbs / 3860 rear
8046 lbs/ 62 psi / 4023 lbs /
8285 lbs/ 64 psi / 4142 lbs /
8524 lbs/ 66 psi / 4262 lbs /
8763 lbs/ 68 psi / 4381 lbs /
9001 lbs/ 70 psi / 4500 lbs /
9239 lbs/ 72 psi / 4619 lbs /
9477 lbs/ 74 psi / 4738 lbs /
9714 lbs/ 76 psi / 4857 lbs /
9951 lbs/ 78 psi / 4975 lbs /
10188 lbs/ 80 psi / 5094 lbs / referencepressure
10424 lbs/ 82 psi / 5212 lbs /
10660 lbs/ 84 psi / 5330 lbs /
10896 lbs/ 86 psi / 5448 lbs /
11131 lbs/ 88 psi / 5565 lbs /
11367 lbs/ 90 psi / 5683 lbs /

[jadatis]

I first searched for european C-tire, and found the Michelin agillis, and have a paper list sent from them, in wich LI 112 AT 65 psi.
After that I searched on LT and found same LI 112 and assumed also AT 65 psi.
BUT, it could be that LT in LI 112 is an E-load. But my system of max reserve is based on laws of nature, and as european guy, I trust that loadindex is not given to high here.

But like to read if someone has this LT in this sise, and confirm if AT 65 or 80 psi.

[MtnGoat]

jadatis I must say that's a compelling explanation. I do see your point to reduce TP to the 65psi range. I think there's more than a few readers here doing a search on the word "sise".

A new set (4) of Bilsteins will be installed tomorrow. I'll hookup and head to the scales. Just to see if the axle weights have changed (the air bags are out now) with the truck rear setting lower. If they're not too busy I'll pump some water into the bathroom grey water tank as well to get somemore pin weight.

[Cincinnati Kid]

Non-expert advice....

Inflate your tires to manufacturers specs, put those factory spacers back in your truck to keep it closer to level, and let the trailer ride a little high in the front. If it bounces too much, try some shocks on the trailer. Put everything heavy (tools, cases of water, soda, etc) as far forward as possible.

I would not put a lot of water in the tanks. If it's a tank that's in front of the axles, it might help your pin weight numbers sitting on a scale, but when going down the road, that water is pushing your trailer all over the place.

I still feel that airbags on the truck make a big difference.

[cadman_ks]

Originally Posted by MtnGoat

...

A new set (4) of Bilsteins will be installed tomorrow. I'll hookup and head to the scales. Just to see if the axle weights have changed (the air bags are out now) with the truck rear setting lower. ...

Shocks won't / shouldn't do anything to change your weights. All they do is dampen the ride. But, if the rear end of your truck is bouncing, ie: moving rapidly in both the up and down direction, shocks will slow that motion...

[TxLoser]

I’d think restoring the truck to proper geometry and not having airbags will help quite a bit. Also, getting as much weight on the pin as possible. Think about this….GM engineers put a lot into figuring out the truck geometry. Jayco…. Not so much or none at all. Shocks certainly won’t hurt with oscillations. Let the HT ride a little nose high. It’s an HT thing.

[Jeff4310]

Hi we pulled our 2017 Eagle HT 24.5ckts 0n a long journey this summer, 8500 miles with our 2021 GMC sierra 5.3l 2wheel drive 69" bed. I also have Anderson conversion. I had minor bouncing on bad bridge abutments. refrigerator came open once.
I brought ours home after purchase and before our first trip. I had airbags installed, started with 30 psi moved to 40. was good.
After trip and coming to this group I saw that shackles were in the upper hole. I had moved to the lower hole " I had tire marks on the sheet metal above tires".
I towed with new tires "Goodyear Endurance" and all seems well.
My question is "Would sumo springs be a good addition to trailer?
I also drove that long trip at 55mph for a blast to the past. 14.5 overall mpg. hope my post is inline.. thx Jeff