Question

which is not a precaution to take when hauling a trailer?
hitching to the trailer before loading it
using safety chains
letting some air out of the rear tires
accounting for the effects of strong winds

Explanation:

When hauling a trailer, hitching before loading helps with balance and stability. Safety chains are a standard safety measure. Accounting for strong winds is important for control. However, letting air out of rear tires reduces vehicle stability and is not a precaution.

Answer:

letting some air out of the rear tires