Commision Implementing Regulation No 923/2012; SERA.3210 Right-of-way.
(d).(4).(iv).(A) vehicles and vehicles towing aircraft shall give way to aircraft which are landing, taking off, taxiing or being towed;
So a taxiing aircraft has priority over a vehicle towing an aircraft.
As an aside, it also says in effect that vehicles towing aircraft shall give way to aircraft being towed by vehicles. Now that really is
