Tire question

I had a flat, and noticed when I pulled the flat tire off that one of
the lug nuts was quite tight, but I WAS able to loosen it. When I put
the spare on, I threaded the lug nut on and tightened it, no problem,
although I did note that the threads were a bit "fuzzy" at the
beginning. When I got the car back from the local tire dealer, I found
the stud totally stripped, and when I brought it to the store
manager's attention, he told me that often happens with old cars, that
the "threads get stretched", that they tighten lugnuts with some sort
of torque measuring device, blah blah blah.

My questions are: 1. Is this true? Is it possible to totally strip a
stud in one go-round? 2. Assuming the stud WAS able to hold a lugnut
before it went into the shop, and ended up stripped afterwards, who
pays for the new stud?
And last, how common is it for the threads of studs to "stretch". To
my inexperienced eye, the thing was put on cross-threaded and then
forced on with the airgun.

Note, the same tire shop has done all my tire replacements for the
last 4 years, and a flat last year had a lug nut on so tight that the
stud snapped when I tried to remove it to change the tire.

Thanks, Carter

 

you are learning one of the great truths in life: NOBODY cares as much about
your car as YOU do! No matter how much you pay them, or how loyal you are to
them, they are just doing their job, and the faster they can get it done,
the sooner they can move on to the next job!

It's been my experience that most auto mechanics set the air wrench on
"high" so they can break lugnuts loose fast and spin them off.
Unfortunately, when they put them back on, they fail to reduce the setting,
and the lugnuts are often tightened excessively, which can cause the threads
to "stretch" and eventually fail. I think the lugnuts are made of a softer
metal then the studs, so usually the nuts are the part that gets the most
damage, and sometimes need to be replaced. Fortunately, that's easy and
relatively cheap (about a dollar per nut).

If a lugnut is overtightened and also corrodes over time, it can end up
frozen to the stud, and breaking the stud might happen, which is more
trouble to replace.

I always coat the threads of the studs with a little wheelbearing grease,
then put the lugnuts on and tighten them REASONABLY tight. I've never had
one come loose in over 40 years of driving.

When I have my tires worked on at a shop, I always drive home, then loosen
each lugnut and retighten it, one at a time, so I know they aren't
overtight, and that I can get them off if I have to someday!

 

You can also request that they use a torque wrench attachment on
the air ratchet that's set correctly, and watch them put the lugs back
on. Much less work for you!

 

The fuzz is metal shavings resulting from someone using an impact
wrench to start and tighten lug nuts. Chances are the threads have
never been cleaned so they are just grinding themselves to death. Air
wrenches have a place for certain jobs, but they are overused by lazy
mechanics.