Team USA's Tyson Gay -- Teammates Forgave Me for Doping ... I'm Back on the Team

Embattled Team USA track star Tyson Gay tells TMZ Sports he'll DEFINITELY be running in Rio next year ... with the full backing of the entire U.S. track community ... despite his 2013 doping scandal.

Gay tested positive for a banned substance a couple years back ... leading many to believe that he'd be persona non grata for the U.S. team at the 2016 Olympics in Brazil.

But when we got the former world champ at LAX he was singing a whole different tune ... telling our cameras that it's all gravy with his fellow speedsters ... and it's all because he was HONEST about his missteps.

"I'm getting ready, man, making sure I stay healthy. USA Track and Field is behind me."