Mutt said: "Did Boeing test the aircraft with new brakes and tires?".
My understanding is that, for certification, the RTO test has to be completed at MTOW with worn brakes and tyres - at least these days. Maybe when the Classic was certificated that wasn't the case? As one of the great uninformed it seems to me that certification requirements should include an additional "real world" second or two for the crew to recognise what's happening before deciding to abort.