Greek God,
Airlines can actually vary the MTOW of their aircraft believe it or not !!
AFAIK most 757-2 have a real MTOW of 113.4, but if the airline reduces this then as a result overflight and air nav charges are reduced (you pay depending on MTOW).
My airline has most pax ones at 102 MTOW, but a few heavier ones for the longer routes.