It appears these were sold in the 1950s and 60s.
Photo of real ones.
Youtube video which shows a few shots of them in action, but it's not the exclusive focus of the video.
The wheels have a larger and a smaller diameter part. That keeps the car from moving laterally off the track, and it probably wouldn't get up enough speed to get air. But, I wonder if some rocking effort would be enough to tip it off to one side. Kids that age are not famous for their self preservation instincts.
Here's a closeup of the wheels.
