Data's show that 95% of single-vehicle rollovers are tripped . This happens when a vehicle leaves the roadway and slides sideways, digging its tires into soft soil or striking an object such as a curb or guardrail. The high tripping force applied to the tires in these situations can cause the vehicle to roll over.

Types of tripped rollovers:

Soft Soil
The driver of a pickup truck traveling down a 2-lane highway at a high rate of speed veers off the right side of the road, attempts to recover by steering too sharply to the left and causes the vehicle to roll over as its wheels dig into the soft soil." This content requires a plug-in compatible browser

Curbs, soft soil/shoulders, guardrails, pavement surface discontinuities,
snow banks, or other objects can cause tripping.

Guardrail
The driver of a passenger car traveling down a 2-lane highway at a highlight rate of speed veers off the right side of the road, attempts to avoid the guardrail by steering to the right. The left front portion of the car rides up the guardrail in a ramp-like fashion, causing the vehicle to become airborne and rollover.
Tripping can also occur when a vehicle is traveling forward, typically at a high speed. If one side of the vehicle rides up on an object, like a guardrail, it may be forced to roll over.

Steep Slope
A sports utility vehicle traveling very slowly in an off-road environment begins to pick up speed as it rides down a steep hill. The driver misjudges the steepness of the hill as a turn to the right is attempted. The vehicle rolls over and tumbles down the hill.
Tripping can also occur on severe slopes in off-road situations. If an incline's slope is too steep to keep the vehicle upright, it can topple over.

One of the best ways to avoid a rollover, therefore, is to stay on the road. Electronic Stability Control is a promising new technology that will help drivers stay on the road in emergency situations.