City are striving to join the London club and bitter rivals Manchester United in securing successive Premier League crowns.
Chelsea boss Jose Mourinho has recruited well in the close-season, including the signings of Cesc Fabregas and Diego Costa, the latter of whom finished top scorer in La Liga last term.
And former winger Tueart – who made over 200 appearances during two spells with City in the 1970s and 80s – fancies Chelsea to push Manuel Pellegrini's men all the way.
"Chelsea look to be our biggest danger," said the 64-year-old, who scored the winner for City in the 1976 League Cup final against Newcastle United.
"I'm not sure how long it will take [Liverpool manager] Brendan [Rodgers] to integrate his new players into his system and his squad.
"I'm not sure whether Arsenal are going to be strong enough and have enough firepower in the last third.
"Man Utd again, no one knows. The window closes at the end of August, so there might be several more new players coming into the Old Trafford squad.
"But I still think Chelsea will be our main danger."
City's title defence starts at Newcastle United on Sunday.