A velocity and acceleration are measured (14) in a method for determining a vehicle reference velocity, said vehicle reference velocity being used for determining and selecting a suitable transmission ratio. If a measured acceleration (a.sub.ist) exceeds (16) a maximally possible acceleration (a.sub.max), a vehicle reference acceleration (a.sub.ref) is determined depending on said exceeding. For this purpose, an acceleration correction value (BKF) is calculated (22) by means of which acceleration correction value a vehicle reference acceleration is calculated (24). The vehicle reference velocity (v.sub.ref) is determined (26) by means of the vehicle reference acceleration (a.sub.ref). A gearbox transmission ratio is determined (20) by means of the determined vehicle reference velocity. This branch of the procedure represents the case in which at least one wheel equipped with sensors slips.