LGT EXPERIENCES RWY EXCURSION AFTER STARTING TKOF ROLL IN SNOW ON RECENTLY PLOWED AND TREATED RWY.

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DE-ICED ACFT; ASSIGNED RWY 27; ON TAXI OUT. CHANGED RWY TO RWY 36L. AFTER RUNNING TAXI CHKLIST; RWY CHANGED TO RWY 27. STOPPED ACFT SHORT OF RWY 27 TO START SECOND ENG AND RUN BEFORE TKOF CHKS AND TO RUN UP ENG PER ANTI-ICE PROC. RUNUP OF L ENG (30 SECONDS AT 70% N1) COMPLETED. TWR CLRED US INTO POS AND HOLD RWY 27. WE WERE THE FIRST ON RWY 27 SINCE IT HAD BEEN SWEPT ANC CHEMICALLY TREATED. R ENG RUNUP COMMENCED WHILE TAKING RWY; BEFORE TKOF CHK COMPLETE. TWR CLRED US FOR TKOF WITH TFC ON 3 MI FINAL FOR INTERSECTING RWY 36L. AS I TURNED THE ACFT ONTO CTRLINE; I PULLED BACK R THRUST LEVER; BROUGHT L THRUST LEVER PHYSICALLY EVEN WITH R THRUST LEVER. TRACKING STRAIGHT; I GAVE AIRPLANE TO THE COPLT (IT WAS HIS LEG). I SAW THAT L ENG N1 WAS 40%; USUALLY WHEN WE ENGAGE AUTOTHROTTLES. HE ENGAGED AUTOTHROTTLES; AND R ENG SPOOLED UP AHEAD OF THE L. ACFT JUMPED TO THE L; WE BOTH PULLED THRUST LEVERS TO IDLE; FULL BRAKING AND STEERING R; BUT ACFT'S NOSEWHEEL WENT OFF THE PAVEMENT APPROX 1 FT. TWR; PAX; COMPANY; CREW ADVISED. RAN AFTER LNDG AND ENG SHUTDOWN CHKLISTS. NO INJURIES; 2 TIRES CUT. PAX LEFT ON STAIR TRUCK THROUGH AFT R DOOR. STATIC TKOF WOULD HAVE PREVENTED THIS; RUSHED CLRNC ALSO CONTRIBUTED.