Practice question

Why drain trailer air tanks when required?

It unlocks fifth wheel
It resets odometer
Water and oil buildup can make brakes work incorrectly
It lowers scale weight

Answer: C — Water and oil buildup can make brakes work incorrectly

The correct answer is shown above. Try the full quiz for additional practice.

Practice more: Iowa CDL Combination Vehicles Test Practice Questions - Iowa Commercial Driver License Combination Vehicles Test Exam →