You're pulling doubles and notice the trailers starting to sway gently on a straight, calm stretch of highway at a steady speed. What is the most likely explanation?

Pick an answer

1. Doubles combinations always sway slightly and it should be ignored
2. Steady highway driving cannot produce trailer sway under any circumstance or road condition once the vehicle has reached a steady speed
3. The sway is caused entirely by the tractor's engine vibration
4. A developing issue such as low tire pressure, an equipment problem, or an unbalanced load on one of the trailers

Correct!

Not quite. The correct answer is highlighted.