an apparatus is provided for removing material from the sidewall of a tire . the apparatus may be used for removing the thin layer of black rubber that normally covers the white letters or white stripe of the sidewall of a newly cured tire , and for buffing the surfaces of such white letters or stripes to give them a smooth finish . the apparatus may also be used for buffing black portions of a tire sidewall to give those portions a smooth finish . the apparatus includes a cutting device and a sensor mounted on a moveable carriage . the sensor measures the distance between the cutting device and a portion of the tire sidewall adjacent to the portion to be buffed . as the tire rotates while it is being buffed , the carriage moves in response to the sensor &# 39 ; s measurement toward or away from the tire sidewall , so that the cutting device removes material at a constant height relative to the adjacent portion of the sidewall .