Electric taxiing (ET) is a novel concept that focuses on replacing engine-powered aircraft taxiing by taxiing using electrically powered towing vehicles, called ET vehicles. The main purpose of ET is reducing the impact of aviation on climate change while at the same time saving fuel costs. In this paper, we propose two models that can be used consecutively to analyse the operational implications of ET. Our goal is to determine the minimum number of ET vehicles required to perform all taxi procedures on a single day at a hub airport. First, we determine the optimal taxi routes for a set of aircraft towed by ET vehicles using a vehicle routing model. Then we find an optimal assignment of ET vehicles to these towing operations, taking into account time and energy constraints and scheduling the moments ET vehicles charge their batteries. We illustrate our models for a quiet and a busy day at Amsterdam Airport Schiphol. The models successfully give concrete guidelines on the required ET vehicle fleet size and infrastructure needed for the implementation of ET. The number of required ET vehicles can be decreased by tactically distributing battery charging over the entire day. Improved battery capacity and power can also effectively decrease ET vehicle fleet size.