§ 74.030  SUSPENSION SYSTEM.
   (A)   It shall be unlawful to operate a motor vehicle on any highway of this city when the suspension system has been modified from the original manufactured design by lifting the body from the chassis in excess of three inches, or to cause the horizontal line from the front to the rear bumper to vary over three inches in height when measured from a level surface of the highway to the lower edge of the bumper, except that it is unlawful to operate a street rod or custom vehicle when the suspension system has been modified from the original manufactured design so that the horizontal line from the front to the rear bumper varies over seven inches in height when measured from a level surface of the highway to the lower edge of the bumper.
   (B)     Nothing in this section shall prevent the installation of manufactured heavy duty equipment including shock absorbers and overload springs, nor shall anything contained in this section prevent a person from operating a motor vehicle on any highway of this city with normal wear of the suspension system if normal wear does not affect the control or safe operation of the vehicle.  This section shall not apply to motor vehicles designed or modified primarily for off-highway racing purposes while the vehicles are in tow or to motorcycles or motor-driven cycles.
(ILCS Ch. 625, Act 5, § 12-607)  Penalty, see § 70.999