The crucial decision about when self-driving cars are ready to deploy is likely to be made with insufficient lagging metric data to provide high confidence in an acceptable safety outcome. A Positive Trust Balance approach can help with making a responsible deployment decision despite this uncertainty. With this approach, a reasonable initial expectation of safety is based on a combination of a practicable amount of testing, engineering rigor, safety culture, and a strong commitment to use post-deployment operational feedback to further reduce uncertainty. This can enable faster deployment than would be required by more traditional safety approaches by reducing the confidence necessary at time of deployment in exchange for a more stringent requirement for Safety Performance Indicator (SPI) field feedback in the context of a strong safety culture.