Agree with all the comments above.
As the machine travels front to rear, it is looking to count each tire. If the tire finder photoeyes can see through the wheels of the car, they may not count correctly. Ideally, if your bay is relatively flat (1/8" per foot fall to center), you want the centerline of the tire finder photoeye to be set to about 3-1/2". If you have much more slope than this, the car is essentially lower in the bay making it easier for the tire finder photoeyes to see through spokes in the wheel. A way you can test this is to find a car that's doing it on, and place a cardboard cutout behind the wheel and see if it still travels to the rear endstops (at the entrance of the track). If it stops properly just behind the rear of the vehicle with the cardboard, I would recommend you try lowering your photoeyes slightly until they can detect the tires.
There have been some minor changes over the years to some of the logic related to that code too. If you can tell me what program and revision is installed in your location, I can check into that for you. From your main screen on the HMI, go into the "information screen", then look for PLC Program Information. Based on the HIM you are using, it's likely either a 25696-XXX series program, or a 27651-XXX series program. What is the number and revision?