Mr. Zimmerman doesn't need an excuse to hit the highway; over the years, he's played in support of good albums, bad albums and no albums at all. This time around, however, his tour takes place amid the launch of a memoir, Chronicles: Volume One -- and if that isn't proof that members of the generation for whom he once served as a conscience have reached a certain age, nothing is. Several early reviews of the tome have mentioned Dylan's admission that during his mid-'80s travels with Tom Petty, he was at a low ebb creatively, which helps explain why the performance I saw him give during that period was about as satisfying as a lap dance from a drunken relative. In contrast, the concerts he put on around the release of 2001's excellent Love and Theft were legitimately impressive -- a helluva achievement for someone entering the fifth decade of his career. There's no telling if his upcoming local appearance will gravitate toward either of these extremes or wind up somewhere in the fuzzy middle. But at least ticket-buyers now have the option of deciding afterward if the book was better.