If you have the original drop axle
it shouldn't rock at all, If it has a replacement straight axle
, that "might" change the tracking and/or towing dynamics, but it's not a commonly heard problem.
Several things to check:
Tire pressure and age: Older tires
a susceptible to delamination and out of round condition. Any tires
over 6 years old should be replaced as a matter of safety. You should have tires
marked ST (special trailer).
Balance tires and/or out of round wheels might also be a consideration.
: As an easy check, put three packages of 30 or so one liter bottles on the floor at the front of the trailer and see if that makes a difference. On mine, if I'm not at 10% or better, it sometimes tries to wander.
Hitch Condition. I had to replace the receiver on mine as it would not tighten against the ball. A snug hitch is a must.
Now, mine sometimes rocks, but I just post a sign on the back door like this:
"When this Hunter is a Rockin' don't bother knocking".