The former owner of that (local) haunted attraction had a history of not doing what was expected when it came to the safety of his customers. An investigation into this particular matter revealed that, although he claimed to have certain people in charge of safety and inspection of the tractors and wagons (the tractor drivers were responsible for examining and maintaining their own equipment), not enough was done when it came to the proper behind-the-scenes operation of the event. In an investigation conducted after the conclusion of the event, it was discovered that he cut corners whenever he could to save money on various things to the extent of going out of his way to purposely hide things from state inspectors when they came around for periodic inspections.
While it is entirely possible that "someone" might have purposely tampered with the lug nuts on that tire, if the owner would have had a DAILY safety inspection of all equipment as he originally said he had, then the incident would not have happened! For instance, the haunted attraction that I presently volunteer at has a daily safety inspection sheet that needs to be filled out and approved by the owner before the event opens to the public.
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