In these cases the failure was not caught by the Tech Centres on inspection before an event. The failure may have occurred only at the track but who really knows in these cases. My personal feeling is that the checking of rims is not done by 100% of the people 100% of the time. I can only imagine what would happen to a car and driver if one were to fail on one of Mosport’s high speed corners.
Your signature on the tech forms really says that in your opinion the car is as safe as it can possibly be for our events. This means to me that even though the tech centre does all the mechanical checks it is your responsibility as well to do the checks that you can. In most cases this is a visual check everyone should be doing and is very easy to do.
As our cars get older there has been talk of even some of the older style Porsche rims in use for years just starting now to fatigue and fail. Many of us have aftermarket rims which look nice but may not stand up to the rigors of track use. On the older rims which we swap around to different owners you have no way of truly knowing the service life that these rims have seen.
It is therefore in your best interests to start doing your own visuals on the rims to look for cracking in the spoke area at the very least. Rims which have been turtled can also crack in the flat surface area resulting in a slow leak here as well.