The Town striker scored twice in five minutes and added a third late in the second half as the lowest-ranked team remaining in the competition saw their cup adventure ended.
After surviving a series of half-chances Redbridge fell behind when Tubbs tucked away a penalty in the 31st minute. Dan Trenkel tripped Kyle McFadzean in the box and Tubbs slotted the resulting spot-kick past Motormen goalkeeper Adam Rafis, nephew of former England captain Tony Adams. Five minutes later Tubbs struck again with a spectacular 25-yard effort.
Redbridge almost scored in the early exchanges of the second half when striker James Robinson, grandson of Jimmy Greaves, dribbled past three Crawley defenders before firing wide.
Vincent Durrant was shown a straight red card for a foul on Tyrone Barnett inside the area and Tubbs completed his hat-trick from the spot with 11 minutes remaining.
Town sealed victory when Andy Drury volleyed in a Sergio Torres cross from 10 yards in the 83rd minute and McFadzean completed the scoring in injury time, lashed home from 20 yards.