5er sways over 65mph

[BillPenn]

Have a 2014 Dodge 2500 Crew Cab 6.7L Diesel pulling a 32’ Thor 5er (dry weight 11500). New truck pulls great with plenty of power to spare. Only one problem, if I get over about 65 mph the rear of the trailer will start to noticeably sway. Can’t feel it in the truck, but you can see it in the mirrors. If I slow to below 60 mph it will stop. I replaced my tires this year with new Good Year ST225/75R15 load range E, and have them inflated to the recommended 55psi. With the trailer hooked up it sits fairly level, maybe a little down in the front. Any suggestions on stopping this, or is it normal? Not looking to do 90 but would like to maintain the speed limit.

[GoPackGo]

Milt wrote:
Maxxis has an E rated tire in that size. Pressure should be around 75 psi.
Milt

I run 16 inch Maxxis E rated tires. They call for 80 pounds pressure.

[TurnThePage]

I'm also in the group that believe the tires are under inflated. What "manual" recommends that? Inflate to max pressure recommended on the side walls. That's the fastest, simplest first step.

[Allworth]

LT

LT

LT

Slow down and enjoy the world as it passes by!

[ependydad]

I've also wondered about checking the trailer's alignment. You would think that you would see issues sooner, but still makes me wonder.

For all of the 65 is the max speed folks-- most ST tires are only rated to 65mph, but their are some that allow you to go faster. Goodyear has the +10mph published; Maxxis responded to a dealer inquiry with similar information; and Greenball ST tires have a 75mph speed rating.

[attuco]

Once I had a fiver start swaying while going downhill. I checked and found the pin box bolts had loosened. I tightened them up and the problem was resolved. Easy enough to check.

[Milt]

Maxxis has an E rated tire in that size. Pressure should be around 75 psi.
Milt

[ScottG]

I dont know what owners manual says 55 psi but that is the first red flag.
Up the pressure to 65 and make sure it tows level. After that I doubt it will sway anymore.

[wilber1]

Again, air the tires up to the max sidewall pressure. Try the simple stuff first.

[352]

ol Bombero-JC wrote:
Follow the good logical advice others have given you.

Skip the sea stories by posters (someone passed me doing 85mph).
Gee Whiz stuff isn't going to solve your problem..:S

Start by dealing with "what you have".

*NOT* with what would/could/should be better.

Save that for "Round Two, Plan B" - or whatever you want to call it.
You may have to do that - but what you have *now* - is what you have.
There's obviously something amiss - or you wouldn't have posted.

For openers, tire pressure at the max pressure indicated on the sidewall of the tire.

(*IGNORE* the Goodyear "plus ten psi" recommendation.)

Determine the pin weight - by methods indicated.

Then determine if the trailer is level, and if not - work on getting it level......then repeat checking the pin weight.

One of the major advantages of a 5th over TTs is the lack of sway.

If you are encountering sway - without heavy crosswinds - there *IS* something wrong.

Almost everyone has gone over the "magic" 65mph - either accidentally or intentionally - without sway.

For those folks - guess your problem would be there at 66mph, and gone at 65mph = double duh..:R

~

Ain't nothing better than telling it like it is. I just didn't want to spend the time typing it.

[phillyg]

The magic of a FW is lack of sway under normal and even abnormal conditions, like high winds. Are you sure you have ST tires? If so, sounds like they need to be maxed out at 65psi. If they're LT tires, perhaps (but I doubt) the sidewalls are too flexible for the carried weight. Like others have said, you need to make sure your hitch is correctly located over the axle and that you have at least 20% of the FW weight on the hitch. Sure sounds like a tire or pin weight issue to me.

[goducks10]

Goodyear does not make an ST tire that requires 55psi. Only 50, 65 and 80psi. Apparently you have some odd ball GY tire that's not rated for trailer use. JMO but I would get rid if the current tires on the 5er and go with something that supports the loaded weight of your 5er. An 11,500lb dry weight 5er will be pushing 13,000 all loaded up. Goodyear doesn't make any ST tire that supports 13,000lbs total on all four tires.

Even subtracting 20% for pin you'd have 10,400lbs on the axles.
Four 225/75/15 D rated tires =10,160lbs.
There are no 225/75/15" GY E rated tires.
Maxxis makes an E rated 225/75/15" tire that gives 11,320lbs total @80psi.

I would seriously think about moving up to a good E rated 16" tire. Run 80psi.

Have you looked on the tires sidewall for max load at ??psi ?
Sounds like your manual and 5er tires aren't on the same page.


Also 55 psi is too low regardless of what tire you're using.

What model 5er do you have?

[BillPenn]

Yep, Load range D, the 55psi is what the owners manual recommended.

[RCMAN46]

How about a picture of your trailer hitched.

Pin weight should be between 20-25% if you what a good towing trailer.

[RogerMo]

If the size you give on the tires is right, they would be D rated. You stated you had them filled to 55 psi, this should be 65 psi as printed on the tires. If you are running them 10 lbs low your lucky the trailer in not swaying at 55 mile speed.