I have seen video footage of B-52s that show that all four sets of wheels are steerable. This allows a B-52 pilot to align his landing gear with the runway and simultaneously crab into a crosswind. This feature also allows a B-52 to perform some unusual maneuvers on the ground.
There are three other bombers with bicycle landing gear: The Boeing B-47 and the Martin XB-48 and XB-51. Were both the front and rear landing gear steerable on any of these three aircraft?