Single axle trailer shackle issues.

I have a little single axle atv trailer. 3500 lb axle. 14 foot trailer This morning we load up three quads on it. Leaving the neighborhood I hear this loud squealing sound. Jump out look it over don't see anything wrong. Keep on going. Get a couple more blocks down the road and hear it again. Pulled into the high school parking lot to check it out. Guy behind me stops and tells me my tires are smoking. So I get under the trailer to see that the shackles are flat against the frame and the tires are rubbing the wheel well. So I unhooked went and got my car hauler. Swapped the quads onto that. So now that there is no weight on the trailer the shackles are about a 45 degree to the frame. I believe they should be close to 90 degrees. So as I think about this the only thing that makes sense is the springs are worn out? Any ideas or suggestions. I have not torn into yet.

The springs might be worn out or bent, if this is new behavior for this trailer. You could replace the shackles with longer ones (just flat bar stock steel) and that may help.

Springs are worn out (more likely) or too much weight.
Shackle mounts are too far forward (less likely, but possible).

Bad bushings in the shackles and springs allowing things to travel more than they should maybe?

Ideally, the shackles should never be able to lay flat on the frame even with the leaf fully compressed (flat - at it's longest length.) Of course, that doesn't mean all trailers are built that way.

In a pinch, Hickey's idea of longer shackles should fix your issue for now.

Henderson trailer has new Springs and hardware for under 50 bucks. I think they will be delivered tomorrow.

Got new springs installed. I loaded two quads on it not a problem. Put three quads on it and same issue. So I measure the distance center to center on the mounts 24 3/8 of inch. Do a little google search and found that the specs are 24 7/8 center to center of the mounts. So basically the trailer was built wrong. This is the first time I have ever put three quads on this trailer so it had never been an issue. This weekend I will cut the rear mount off and move it.