Kanye West and his wife went out for a movie date Tuesday in Los Angeles, and Bianca didn't feel the need to support her tatas with a bra ... instead putting the goods on full display in a VERY sheer top, if you can even call it that.

We're hearing Ye and Bianca got a couple tickets to "Fly Me to the Moon" -- starring Channing Tatum and Scarlett Johansson -- but folks who were there say the pair bounced after only 45 minutes.

Unclear why Kanye and Bianca made an early exit, but her busty display certainly may have been a factor ... as you know, she's often out looking just like this in public -- and, frankly, some have suggested the way she dresses isn't all that appropriate.

Another funny tidbit about this outing ... Kanye seems to have misplaced the keys for his Cybertruck, because they couldn't get in the Tesla and had to dip back inside the theater.

The good news ... Kanye and Bianca being locked out gave photogs more time to snap some sexy shots of her see-through top -- something Ye appears to be somewhat skittish about lately.

Credit where credit's due ... Bianca's not just bringing big breasts to the table -- she's got legs for days too!