(A) No vehicle shall be backed to the curb on any street; except that, wagons and trucks may do so when loading and unloading; provided that, such loading and unloading and delivery of property and material shall not consume more than 30 minutes.
(B) Such backing of trucks or wagons is prohibited at all times and on all streets in the city where any truck or wagon so backed interferes with the use of the roadway of moving vehicles or occupies road space within ten feet of the centerline of the street.