A truck accident caused by jackknifing is often catastrophic and can involve many other vehicles. In most driving situations, they’re avoidable provided the truck driver is skilled, understands their causes, and actively avoids them. Here are four of their causes: Light Trailer Loads Hauling a lightly loaded trailer doesn’t by itself cause jackknifing, but it makes the tractor-trailer combination more susceptible to the problem. Tire traction with the road requires weight pressing down on the wheel. The more weight in the trailer, the greater the tire traction. The tires of.