Abstract: A booster dolly for use by tow trucks is disclosed. The booster dolly is useful where a blowout or wheel bearing failure in a trailer has occurred as might happen to submersible boat trailers. The apparatus incorporates in the preferred embodiment an axle brace which supports slidable mounted V-shaped pillow blocks. They are moved along the axle brace to locations where they then support the axle of the failed trailer thereabove. One of the two pillow blocks stands taller than the other and it is provided with a downwardly extending portion which adjustably connects with a tandem brace. The tandem brace is adjustably maintained at some distance below the axle brace. The tandem brace is drilled with appropriate mounting openings to receive a set of dolly wheels thereon, the dolly wheels mounted on removable stub axles and being pin fixed in position. This apparatus enables a failed trailer to be carried on the dolly.