[E90convert]

In every bolted joint design, analysis, and testing I’ve ever done, the fastener is to be the failure point, not the female threads. Going from an 10.9 to 12.9 may change the failure mode to the female threads whether you tighten it more or not simply because it is a stronger material. This does not address the stiffness change of the fastener and subsequent increased alternating fatigue amplitudes the 12.9 fastener will see. BMW may still have switched to a 12.9, but they have done the calculations, analysis, and testing to prove it. The stud material, manufacturing process, and coatings all play into the testing. And likely would be using a modified 12.9 spec to avoid HE risk. So if they are 12.9, those are the only 12.9s I would use. Track/S Unless that bolt gets sectioned, ground, and checked around the core, the data isn’t really useful. Surface measurements on a fastener don’t tell you the full story (hence why that first fastener was out of spec)

Also a stronger hub does not automatically imply that thread stripping is a problem. It could more than likely be a fatigue problem. All the wheel loads go through the hub and then the bearing so there is quite a bit of alternative bending fatigue on that part. Force amplitudes are magnified with racing slicks. Supporting what F87 uncovered.