About the biggest crime in wheels is where the fathers pressed the bearings out and put precision-made ball bearings in. Also they will buff the rubber down about one-eighth of an inch, and then dip the whole wheel in a solution or just plain white gas and by chemical reaction the rubber will react to this treatment and will be twelve inches again (wheels are all the same diameter: 12″). The rules specifically say you must not tamper with the wheels at all.
My late father-in-law wrote this in 1957 for his high school composition class. I just found this paper about his experiences as a soap box derby builder today as I was cleaning up the house. He got a C+ for the paper (see the teacher’s remarks at the end). He never was a very good speller. I think he had a touch of dyslexia. In any case, it’s an interesting look at soap box racing in the 1950s.