Why are my lug bolts breaking

I am having trouble with lug bolts breaking. Possible reasons?

Over-torquing.

Tester

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There may be an error in translation . . .

Your car doesn’t have lug bolts . . . it has lug nuts

And the hubs have studs, onto which the lug nuts thread

Which is breaking?

The nut?

The stud?

Are the lug nuts and studs extremely rusted?

And how are you going about tightening the lug nuts?

the studs are breaking

Are they extremely rusty?

No offense, but is there any way you’re cross-threading the lug nuts when installing them?

Are you using some kind of an impact wrench?

Usually hand install, so I’m not cross threading. Then I use a star wrench to tighten. Don’t have a torch wrench. I tighten them as much as possible, as long as I can still loosen them. Seems to occur mostly in the front. I use the car for rural mail delivery, so the roads are not the smoothest.

You don’t have any lubricant on the lug stud threads?

Tester

no lubricant

I know in my younger days if I tightened lug nut with a cross wrench ( I don’t know what a star wrench is ) as tight as I could get them with a 14" cross wrench I would have been snapping studs all the time. That is way too tight.

Harbor freight has click type ratcheting torque wrenches on sale frequently for $9.99, You don’t need a great torque wrench for lug nuts, It is fine if they are a few pounds off.

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Are they breaking when you tighten or loosen them ?

Are you using the proper style lug nut for your wheel ?

Probably too tight. Take @oldtimer-11 advise or borrow a torque wrench to see what the correct torque feels like.

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Are the rims hub centric? If you are using universal rims instead of the OEM that came with the car, the weight of the vehicule could be riding on the studs and not on the hub. Metal fatigue could be the result of that.

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Either over tightening or metal fatigue from stress of driving. How old is the Buick? Miles?
Are you hitting a lot of curbs?

This really seems strange . @vmlbsweber_143747 it might help if you could give more information. Such as - how long have you had this vehicle - is this a recent problem - does the replacement wheel stud break - the roads should not be a factor as you are really going very fast - have you changed from factory wheels to after market ?