Wheel crushes involve a number of scenarios, but most of them involve negligent mirror adjustment or usage. The most typical scenarios include:

• A just-alighted passenger does not (or cannot – because perhaps a plowed snow-bank prevent his or her movement away) move away from the “danger zone” around the curb-side rear tires before the bus pulls out, and slips beneath the tires the very moment the driver has finished “clearing his mirrors.”
• Drivers’ simply do not clear their mirrors, and simply pull out when just-alighted passengers or other pedestrians are walking or loitering around the rear tires.
• A passenger chasing the bus as it pulls away begins to catch up (a large bus begins its acceleration relatively slowly, because of its mass), does do, pounds on the bus in anger (or hopefully to stop it, in order to board), and invariably spins beneath the curb-side rear tires.
• A schoolchild who missed the school bus runs down the street, and catches it just as it begins to make a right turn, and because of the way buses turn, the “steel wave” of the body begins to move toward him, knocks him (or his bicycle) down, and the curb-side rear tires ride over his torso during their hypotenuse-shaped short-cut when they are dragged around the corner by the driver’s proper right turn.
• A passenger thinking she was being stranded by her motorcoach, runs after it, catches the front of it, and pounds on the door. Because the driver intended only to drive into the maintenance garage for a few minutes, he does not let her aboard, and she falls beneath the curb-side front tires as it makes its right turn toward the garage.

There are certainly other variations. I have just not encountered them all yet. Regardless, the tort occurs because the driver didn’t use his or her mirror properly, or did not react to the situation responsibly – most by failing to immediately stop the vehicle, particularly since most wheel crushes are preceded, only seconds before, by the chaser pounding on its exterior (which sounds like a loud tympani strike to those in the inside) accompanied by one or more already-on-board passengers informing the driver that someone else wants to get on board. Such cases are very difficult to defend, usually bring high settlements, and play poorly at trial. Because the tire treads of a 38,000-lb. bus make quite an impression on a squishy Earthling’s body, jurors spend days starting at a horror-movie style mutilation that they nearly vomited upon first seeing.