In contrast to a part-specific general operating permit, a part-specific technical report is not always a direct permit to execute a structural amendment. But: The part-specific technical report generally includes a section on “Fields of application”. For example, this may read as follows: “The amendment described in the appendix to the vehicle listed may be executed in consideration of the conditions and information provided”. In this case, the part-specific technical report is in fact a direct approval for the retrofitting of the wheel/tyre combination specified in the appendix. And in exactly the same way, Volkswagen has the respective part-specific technical reports from the MOT association for the approved wheel/tyre combinations named in the CoC.
Most importantly, however, a part-specific technical report contains the requirements concerning the correct installation of the particular part. Without an approved appendix, an MOT facility (or a comparable testing facility) will have to check that the retrofitting has been conducted correctly in accordance with the technical report. The structural amendment to the vehicle must first be successfully tested before it can be added to part I of the registration certificate, formerly the vehicle registration document, by an accreditation office.