Not sure I understand problem correctly.....but the studs are bigger and goes through the hub then the drum.
According to your measurements there is an eighth of an inch difference which seems to be quite a bit of difference.
The studs are bigger where they go into the hub but the threaded part should be smaller...and in my experience the drums holes are just a "tat" bigger than the threads.
Perhaps the place you bought the stuff needs to recheck the part numbers??

...surely someone who has worked on this recently will chime in.


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