The bystanders are leaning to the left, because the camera was moving to the right - there was relative movement between camera and bystanders.
The wheel is leaning to the right - because there also was relative movement between camera and car. If there hadn`t been relative movement between camera and car, the wheel wouldn`t lean to any side.
But there was relative movement between camera and car, because he was panning too slow. That`s probably also the reason for the car not being mid-frame, he was panning too slow and releasing too late to get the car mid-frame, undistorted.
This could be a blown shot.
As others explained the wheel was closer to the camera, therefore being distorted more, but still the car also must show distortion, so the number 6 actually should have been upright. The other wheel is even further away from the camera, therefore showing least distortion (but also still should have some dist.) .