Katie Puwalowski died Tuesday afternoon at UPMC Mercy hospital where she was taken after the Monday night accident on Interstate 376, which is known locally as the Parkway West.
State police are still investigating, but they say a tire fell off an SUV traveling in the opposite direction, bounced over a concrete barrier and hit the roof of Puwalowski's car. Her passenger was able to safely steer the car off the highway.
The passenger was treated and released from a hospital. The driver of the Jeep Grand Cherokee that lost the tire wasn't hurt.