[dparm]

Thanks, gills. What I am still trying to find data on is "how do I know it's time to replace studs" -- the aftermarket would love for you to buy new ones, and shops would also love it so they can make a few bucks. I understand the benefits of a longer stud making wheel changes easier, or being necessary with certain wheels to ensure the nuts have enough thread. I'm not really worried about either of those use cases.

My factory studs are grade 10.9. As I understand it, ductile steel used in wheel studs (or any bolt) are typically torqued to ~90% of the yield strength of the steel. Any loads less than the yield strength result in the bolt working in its elastic region. This means if you release the load, the bolt returns to its original length and zero stress. If a bolt is “stretched” it means that it was stressed past its yield strength. The trick in spec’ing a bolt or stud is understanding the worst case loads it will see. If the load ever exceeds the yield strength, then the bolt gets permanently longer. This means that since it is longer, you also lost some of the clamping force and the nut is loose.

So in other words, if you follow the GM torque spec (100ft-lbs), you are keeping it in the elastic region and the lifespan is virtually infinite (excluding outside factors like corrosion, impact damage, etc)?