Trailer Sway: What Causes It, How to Prevent It, and What to Do
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Trailer sway is the side-to-side swing that can build until the driver loses control. It's almost always preventable, and knowing how to react matters just as much.
What causes sway
- Too little tongue weight — the most common setup mistake. Under about 10% of the trailer's weight, the trailer becomes unstable. See tongue weight explained.
- Heavy cargo loaded behind the trailer axle.
- Crosswinds and the air pushed by passing trucks.
- Speed — sway builds faster the faster you go.
- Low or uneven tire pressure on the vehicle or the trailer.
- A trailer too heavy for the tow vehicle — see towing capacity terms.
How to prevent it
- Load heavy items low and forward of the trailer axle, and keep tongue weight in the 10–15% range.
- Tow level with the right ball mount drop or rise.
- Use sway control on larger trailers — a weight distribution hitch with integrated or add-on sway control.
- Check tire pressure on both vehicles before you leave.
- Slow down, especially in wind and when large trucks pass.
What to do if the trailer starts to sway
| Do | Don't |
|---|---|
| Ease off the accelerator smoothly | Slam on the tow vehicle's brakes |
| Hold the steering wheel steady and straight | Steer sharply to "correct" the swing |
| Apply the trailer brakes on their own with the brake controller's manual lever | Speed up to try to pull out of it |
| Once it settles, pull over and find the cause | Carry on at the same speed |
Applying only the trailer brakes pulls the trailer back in line behind the vehicle, which is why a properly set up brake controller is such an effective safety tool — CURT lists sway correction as a use of the manual control.
Browse weight distribution and sway control and brake controllers.