A hub centering ring for aftermarket alloy wheels for your car. Usually aftermarket wheels have a large center bore so that they are applicable on many makes of car with the same wheel stud pattern. It is advisable to locate these wheels with a plastic spacer ring such as this one.You need to adjust the inner and outer diameter of the ring for your fitment. The default parameters are for an OZ (CB 75 mm) wheel on a Ford hub (63.4 mm).MIT licenced.Find out the inner and outer diameter. The outer one will most probably be printed inside the wheel. The outer one depends on your car, you can find it online, e.g. here: http://www.carlsalter.com/all-wheel-fitments.htmlEnter the required diameters in the SCAD file, and compile.Print.