Vr speed is based on IAS. Assuming in both headwind and tailwind situations the Vr is the same, the aircraft should behave exactly manner aerodynamically (time to lift off, pitch at lift off.. etc) if both takeoffs are done precisely the same way. The only difference here is the resultant groundspeed - in a tailwind more ground covered. I do not think there is an increase risk of tailstrike as well in a tailwind situation. Unless we are talking about a sudden lost of headwind component (sudden reduction in HW or increase in TW) during rotation, resulting in the IAS and thus lift to decrease at this moment especially with the aircraft at its take-off performance limits and the pilot keeps pulling back.