Rule 6.11 Wheels
All fasteners and hardware (i.e. nuts, bolts, collars, etc.) that are used to secure a buggy’s wheels to that buggy shall be equipped with locking devices such as lock nuts, lock washers, lock wires, cotter pins, etc. The use of anaerobic locking compounds (such as Loctite) is permissible,but is not sufficient.
No buggy may use any official soap box derby race wheels if those wheels are constructed of any type of plastic material. Experience has shown that these wheels, while adequate for straight line soap box derby racing, are structurally deficient in buggy racing applications.