Paramount Pictures' "Transformers: Dark of the Moon" grossed $37.2 million on Wednesday in its first full day of play at U.S. and Canadian box offices, giving it the best opening-day gross of 2011.

Including the $5.5 million earned in Tuesday night sneaks, the Michael Bay tentpole has grossed $42.7 million in domestic theaters during its first two days.

The movie is doing strong business in 3D locations, bucking the recent downturn in 3D attendance. Roughly 60 percent of the ticket sales are coming from 3D theaters, including Imax runs, which have raked in a strong $3.3 million.

So far, "Dark of the Moon" is seeing ticket sales running ahead of the first "Transformers," but behind its sequel "Transformers: Revenge of the Fallen," which grossed $62 million in its first day. "Revenge of the Fallen" opened on a Wednesday in 2009. Comparisons are difficult, however, because of differences in calendar days and the marketplace.

"Dark of the Moon" got an "A" grade from research firm CinemaScore, while 55 percent of Wednesday's audience was under the age of 25, a good sign for the movie's prospects. The last film received a grade of "B-plus".

Wednesday's ticket tally includes $8 million in midnight shows, but doesn't factor in the $5.5 million earned earlier Tuesday night from special 3D sneak previews.

Previously, the best opening day of the year belonged to Disney's "Pirates of the Caribbean: On Stranger Tides," which debuted to $34.8 million, including $4.7 million in midnights, on a Friday.

"Dark of the Moon" should pick up noticeably as the July 4th holiday weekend gets underway in the United States. Still, Paramount is prepared for the three-quel to come in behind "Revenge of the Fallen," which grossed roughly $200 million in its first five days. Paramount expects "Dark of the Moon" to gross $155 million to $170 million through July 4th, closer to the opening gross of the first "Transformers."