(a) No vehicle equipped wholly or partly with solid rubber tires shall be operated upon any highway at a speed in excess of 10 miles per hour.
(b) No vehicle transporting any explosives as a cargo or part of a cargo shall be operated upon any highway at a speed greater than that designated on the permit issued by the State director of labor and industrial relations or as indicated by the prevailing speed limit on that particular road; and these vehicles shall be routed over the freeway system only when they are permitted to travel at least at the minimum speed limit for the area.
(Sec. 15-7.8, R.O. 1978 (1983 Ed.)) (1990 Code, Ch. 15, Art. 7, § 15-7.8)