There is a city ordinance AND a zoning ordinance prohibiting commercial vehicles from being stored in a residential area. The police will not ticket a commercial vehicle if parked in a residential driveway, and there is no one from zoning available after 5 p.m. making that ordinance unenforcable.
Elmhurst City Ordinance # 44.126:
Parking of commercial vehicles in residential areas prohibited.
It shall be unlawful for any person to park a commercial vehicle on any public road, street or way located within a single-family residential zoning district except when making a delivery or rendering a service at premises located within such zoning district. For purposes of this section, "Commercial Vehicle" shall be defined in Section 1-114 of the Illinois Vehicle Code and having a gross vehicle weight in excess of eight thousand (8,000) pounds. (7/15/91)
Elmhurst Zoning Ordinance 4.2-4f:
Commercial vehicles may not be parked overnight in any residential district, other than in completely enclosed buildings or garages, except when the vehicle is present for the purpose of providing a required service to the residence where parked, but only for that period of time which is required to provide the service.