My earlier post got whacked, so I'll try again. The largest theropod track I've seen reported is in Lockley and Hunt's book, Dinosaur Tracks (1995, Columbia University Press). They attribute the track to Tyrannosaurus rex and report it at 85 cm in length (based on the scale drawing in the book, it looks as if it's about 60 cm wide). I'd be interested in knowing if this track has been reinterpreted or if larger theropod tracks have been found since then.
PTN