Tara Reid HAMMERED DRUNK -- Takes Down Parked Motorcycle

Tara Reid was a drunken mess in St. Tropez this weekend -- sloppily stumbling into a parked motorcycle, sending the bike and herself crashing to the ground.

TMZ obtained footage which begins moments after the fall -- Reid is sprawled out on the ground next to the bike ... while her equally hammered female friend is slumped across the top of the downed vehicle.

Several people try to help Reid off the ground ... but she struggles to pick herself up.

Once the two women get on their feet, both drunkenly sway back and forth in what seems like an epic battle to stand still and compose themselves.

Eventually, the two women wobble over to a nearby yacht ... and board the vessel like they had been there before.

Reid has been through rehab for alcohol addiction -- completing a 60-day stint at the famous Promises Treatment Facility in Malibu back in 2009.

12:40 PM PT -- Tara Reid just responded to the video on Twitter, saying, "TMZ are liars and they always againt me [sic] they pushed us down that's why we fell ... Its a set up!"

She adds, "I will defend us this time 100%."

TMZ did not shoot the video -- but a rep for the agency that did, Spread Pictures, says, “We weren’t close enough to touch her, unfortunately. We were careful to stand back because Tara on a moped sounded like a bad idea even before she and her friend fell!”