Michigan Commercial Driver's License (CDL) Practice Exam

If your brakes get wet while driving on a rainy day, what can happen when you apply the brakes?

1. The brakes may completely fail

2. The vehicle may skid sideways

3. Trailer jackknifing

4. The stopping distance will be shorter

The correct answer is: Trailer jackknifing

When brakes get wet, particularly in the context of air brakes, one of the potential outcomes is that the stopping ability of the vehicle can be compromised, leading to trailer jackknifing. This occurs because wet brakes can reduce friction, making it harder for the vehicle to slow down effectively and evenly. If the trailer is not aligned properly with the cab when brakes are applied, the trailer may slide out to the side, resulting in a jackknife situation. It's also important to note that while brakes may not completely fail outright, the effectiveness of the braking system diminishes, increasing the risk of skidding or losing control. This underscores the importance of understanding how adverse weather conditions affect vehicle dynamics and the necessity of adapting driving techniques accordingly.