FLC OF ACR MLG EXCEEDING TXWY LIMIT WT AT GRR.

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PRIOR TO COMMENCING THE APCH; I BRIEFED THE RWY IN USE; ILS BACKUP TO A NIGHTTIME VISUAL APCH. THE RWY WAS PLOWED AND SANDED WITH BRAKING ACTION 'GOOD.' I BRIEFED AN EXIT PLAN WITH A L TURNOFF OF RWY 8R. WE RECEIVED A VISUAL APCH CLRNC FROM 12 MI OUT AND COMPLETED THE APCH AND LNDG UNEVENTFULLY. EXITED THE RWY ON A FORWARD HIGH SPD A3 AND TWR SAID 'TAXI TO THE GATE AND REMAIN MY FREQ.' CTLR WAS WORKING TWR; GND AND CLRNC DELIVERY. SHE DID NOT ISSUE SPECIFIC TAXI INSTRUCTIONS AND LEFT THE TAXI RTE SELECTION UP TO US. UPON CLRING THE RWY; THE FO AND I ACCOMPLISHED OUR 'AFTER LNDG FLOWS' AND I MADE A TURN FOLLOWED BY A R ONTO TXWY F. I LOOKED AHEAD AND SAW THAT THE TXWY WAS PLOWED BUT NARROWER THAN USUAL. I SLOWED AND ASKED THE FO IF TXWY F TO TXWY V WAS OK TO GET TO THE RAMP. HE SAID YES. AFTER PROCEEDING TO THE GATE WITHOUT INCIDENT; I CONSULTED THE ARPT DIAGRAM AND FOUND THE 'FINE PRINT.' SEVERAL TXWYS ON THE FIELD WERE NOT STRESSED FOR LARGE ACFT. TXWY F WAS LIMITED TO 47000 LBS (ABOUT 1/2 OF OUR ACTUAL WT). I DO NOT BELIEVE WE CAUSED ANY DAMAGE TO THE SURFACE OF THE TXWY AND I NOTICED NOTHING UNUSUAL. TWR WAS BUSY ISSUING DEP CLRNCS AND SAID NOTHING ABOUT OUR TAXI RTE. FACTORS THAT LED TO THIS EVENT: FAILURE TO BRIEF THE RESTR TXWYS AND A PLANNED TAXI RTE AFTER THE EXIT PLAN. THE ABSENCE OF A SPECIFIC TAXI CLRNC FROM THE TWR CTLR LED TO AN AMBIGUITY ABOUT TXWY SELECTION. FAILURE TO FOLLOW MY FIRST INSTINCT UPON NOTING THE TXWY WIDTH AND STOPPING THE ACFT PRIOR TO ENTRY BEFORE CONSULTING THE CHART. ABSENCE OF SIGNAGE NOTING WT RESTRS WAS A CONTRIBUTING FACTOR; ALONG WITH TRUSTING MY FO TO 'CONFIRM' A VALID TAXI RTE. HOW TO AVOID A RECURRENCE: BRIEF THE TAXI RTE TO BE EXPECTED AND NOTE ALL 'FINE PRINT' ITEMS ON THE TAXI DIAGRAM DURING APCH/DEP BRIEFINGS. I PLAN ON PUTTING A RED LINE THROUGH ALL UNSUITABLE TXWYS ON EVERY DIAGRAM I USE.