I am sure you are after the 'look' of fatter tires but if it were my bike I would run Avon AM26 in the original sizes or you could go with the
metric sized 100/90-19 and 110/90-18(4.5 inches wide). Bridgestone S11 and BT45 are also good choices.
metric sized 100/90-19 and 110/90-18(4.5 inches wide). Bridgestone S11 and BT45 are also good choices.