Its not a 411 alloy its a Britannia wolfrace alloy on a 411. The 6 mm is the depth or thickness of parallel section the wheel stud hole. Put another way if the alloy wheel nut sleeve was longer than approx 6mm it would bottom out against the hub before the taper gripped the wheel.
Not sure what you mean about the but being 17mm - if you mean the sleeve diameter that would make sense.
|