In this paper the characteristics of on-road rollover accidents are discussed. Typical rollover scenarios are presented and the phases of rollover leading up to and including vehicle trip are reviewed. Test data from various vehicle handling test programs are reviewed. The data from a test program that included maneuvers through an obstacle avoidance course are reviewed in detail. This program included tests in which the vehicle successfully traversed the course as well as tests where intentional vehicle tip-ups occurred. Comparisons of the driver input data (steering wheel angle amplitude and steering wheel rate) and vehicle response data (lateral acceleration, yaw rate, body roll angle and roll rate) from this program are presented. A review of previous analytical models of the rollover trip phase is also included. The applicability of these models in estimating the energy dissipation/transfer and lateral impulse leading to vehicle tip-up in an on road rollover is discussed. Additionally, the effects of wheel rim gouging in the roadway surface during the rollover event are examined.