A B777 declared an emergency for landing after they were advised of the loss of some significant part of one or more tires during the takeoff roll. All tire inflations were normal and the eventual landing uneventful.

Narrative

At take-off the Tower and another aircraft's pilot noticed something coming off the aircraft. It was later determined to be part of one of our aircraft tires; mainly tread. Our aircraft cockpit display indicated that all tires still had proper inflation; and it looked like all the tires were still intact. The Captain briefed me on the possibility of the tire blowing on landing; taking other tires out; maybe causing aircraft damage and fire. I asked if we should prepare and do the emergency checklist. He said no; but to be very aware of unusual noises; aircraft attitudes; anything unusual. I briefed the other Flight Attendants. As emergency vehicles would be lined up along the runway; the Japanese speakers were briefed by the Captain on what he would tell the passengers about 35 minutes before landing so they could translate it into Japanese. A First Class Passenger helped with the formulation of this PA; as the speaker wasn't sure of the technical wording. We landed without incident. After coming to a complete stop; the wheel assembly was inspected; and we were given the OK to taxi to our gate. Nine fire trucks followed behind; until we reached the gate safely.