Why did my lug nut studs brake?

I am just curious.

Why did two lug nut studs brake on the same wheel? I am pretty sure I was the last one who touched them. Torqued them to 80 ft/lb.

One just broke when I had to put a breaker bar on it when it stopped moving.
When the second one stopped moving I sprayed it with the penetrating oil but still could not save it. When I finaly removed it the threads were stripped.

The vehicle is 1999 Accord, 4 cylinder with 136000 miles on it.

Regards,
Sam

Wheel studs do break, I do my own rotations these days from past bad experience with "free rotations"

.....and Honda has STILL not realized now for many, many years that wheel studs indeed do break. And yet it takes an act of congress to get them replaced. (on the fronts)

I service my cars myself and this is the first time that happened in so many years.

Somebody suggested that in the past the lug nuts were severely overtorqued. Probably. I bought this car used with 55000 miles on it about 10 years ago. So it just waited to happen.

Another possibility is that the lug nuts reached the end of their life: I wanted to reuse the two remaining ones and they did not want to go. I bought a set of new nuts at Pep Boys and they turned smoothly. I most likely will replace all lug nuts on the rest of the wheels in the future.

Every car manufacturer has its faults and Honda is not an exception. May be 50 years down the road they will design a little notch on the hub and we will be able to slip a new stud in there. But as of now it is a little nightmare to replace a broken stud.

Sam