Tire disablement events can cause a drag force that slows a vehicle’s speed. In this study, the magnitude of the deceleration was measured in 29 high speed tread separation and air loss tests. The tires tested were circumferentially cut to create partial and full tread separations, or prepared to lose air rapidly. The deceleration rates were corrected for the slope of the road, aerodynamic drag and rolling resistance of each vehicle tested. These deceleration rates can assist in reconstructing the speed of a vehicle involved in an accident following a tire disablement.