United Airlines left its mark on San Francisco when one of its flights took off Thursday … and almost immediately lost one of its tires, which came crashing down on parked cars at SFO Airport.

Video captured the moment the Boeing 777 took off bound for LAX with 249 passengers aboard — before the jumbo jet’s landing gear retracted into the fuselage, the massive tire flew loose right above an SFO employee parking lot.

Thankfully, no one was injured on the ground, but there was plenty of damage to some vehicles.

As for the damaged plane, United says it landed safely at LAX, mainly because it’s a 777, which has 6 tires on each of its 2 main landing gear struts. The airline says it’s designed to land safely with missing or damaged tires.

Once it was on the ground, United moved all the passengers to a new aircraft for the next leg of the flight … which is heading to Osaka Thursday evening.

While there were no casualties from this incident, it’s still concerning from the standpoint of it being yet another issue with a Boeing aircraft. You’ll recall, the door blew off a Boeing 737, operated by Alaska Airlines, 2 months ago — leading to a temporary grounding of all 737 Max 9s.

Some ex-Boeing employees have come forward, claiming the company has been cutting corners, safety-wise, in its manufacturing plants — with one former quality manager telling us on “TMZ Live” he wouldn’t put his own family on a 737 Max 9.