My aircraft is a non-fbw widebody airbus. The incident took place at a hot and high airfield where the only performance figures given are for a slat only take off.. Airbus in their performance figures gives limit codes and in this case they were 2nd segment climb and tyre speed.Given the airfield altitude and a nominal temperature and calculating the TAS they give a 5kt margin on exceeding the max tyre speed at the IAS Vr. As a fleet we do not perform many slat only take-offs and Airbus admit that there is an increased risk of tail strike in this config so there may be a slower rotation rate leading to a higher unstick speed,but as you say this is too close to a potentially critical limit.