At least one Lyft driver's got a limit to how much his vehicle will lift ... according to a Detroit woman who claims a driver refused her a ride due to her weight, and now she's taking the company to court.

Dajua Blanding says she called for the Lyft last week to take her to her cousin's house to watch the Lions playoff game -- but when the driver showed up in his Mercedes-Benz sedan, the ride was derailed.

Dajua -- who raps in Detroit under the name Dank Demoss -- says the driver locked his doors and denied her entry. She claims the driver told her she was "too big to fit in the back seat" ... and then it got worse.

She claims he added his "tires were not capable" of supporting Dajua's weight, and he said he'd had this "problem in the past." His solution? She says he told her to order a Lyft XL next time, and then drove off.

Dajua is suing Lyft and the driver for violating Michigan civil rights laws barring discrimination based on weight. She says she's suffered stress, humiliation, embarrassment, outrage, fear and mortification.

A Lyft spokesperson tells TMZ ... "Lyft unequivocally condemns all forms of discrimination -- we believe in a community where everyone is treated with equal respect and mutual kindness. Our community guidelines and terms of service explicitly prohibit harassment or discrimination."