California Class B Driving Permit Practice Test

When brakes are wet, friction between the brake components and the road is reduced, so stopping power drops and stopping distances grow. With a vehicle pulling a trailer, that reduced and uneven braking can cause the trailer’s braking force to behave differently from the tow vehicle’s braking. On a slick surface, the trailer is more likely to skid or to push the back end of the tow vehicle sideways. If the trailer’s brakes grab unevenly, the connection at the hitch can drive the trailer to swing around, potentially turning too sharply and causing a jackknife. That risk makes the idea of the trailer jackknifing the most notable hazard when braking with wet brakes. The other scenarios aren’t as likely to describe what typically happens in this setup: engine stalling isn’t caused by wet brakes, and while brakes can lock or tires can skid, the distinctive danger with a trailer is the possibility of a jackknife.