Deliveries by tank truck vehicles, thirty-six feet long, to and including sixty feet long, to Traffic Zone I will be allowed only during the hours of 10:00 p.m. of any given day to 7:00 a.m. of the following day. Tank truck vehicles less than thirty-six feet long are prohibited in Traffic Zone I during the hours of 7:00 a.m. to 9:00 a.m. and 4:00 p.m. to 6:00 p.m. (Code 1962, § 37-33.02; Ord. No. G-917; Ord. No. G-2817, § 1)