Weird problem, trailer sway and possible 5th wheel issue?

Looks like your trailer isn’t lining up right, which is why it’s wobbling side to side. First thing I’d check is your fifth wheel. If it looks crooked to the right, the kingpin might not be fully seated or the fifth wheel could be a little off. Even a tiny misalignment can make a heavy tanker wander down the highway.

Next, check the trailer itself. A bent frame, messed-up suspension, or worn leaf springs can make it pull. Tires can also cause issues. Retreads or mismatched tires will mess with how it tracks. Make sure all of them are aired up and matched across the axles.

Also look at how the tanker’s loaded. Uneven weight can make it swing more than usual.

Bottom line, start with the fifth wheel and kingpin, then check the trailer and tires, and keep an eye on the load. Most of the time fixing one of those will stop the side-to-side wiggle. If it’s still hunting, get a pro to look at it before you put too many miles on it.

 

My money is still on brand new drive tires with nearly a full inch of tread on them.

 

Do what? True tires? So that they last longer and run out better.

 

Any new tire with deep tread will make the rear of your truck feel loose for a little while. Truing the tires isn’t why your truck feels the way it does. A new tire isn’t perfectly round. So truing them helps them run out better (ie: less likely to have abnormal wear) over the life of the tire.

 

I’ve driven loaded trailers with bad “Shocks” and never experienced your issue. Also, trailers with new tires, no issues neither.