Sorry to hear it -- I've had cars come back from the tire shop with the lugnuts just spun on by hand, forgetting that important step with the torque wrench. Very scary as a driver, and even scarier as a motorcyclist to think of a car wheel turned into a missile.

It's worth buying a large ft/lb torque wrench (which will also get used when you work on your Duc) and re-check the torque on the lug nuts any time someone works on the wheels. While nuts that aren't torqued enough are uncommon (but really dangerous!), probably 80-90% of the tire techs out there just smack the impact gun on there and significantly OVER torque the lugnuts. At the very least it's a huge annoyance if you get a flat and need to try to break the nuts free with one of those dinky 10" lug wrenches that come standard with most cars (also a good reason to carry one of those big four-way lug wrenches in every car), and in rare cases it can lead to lug failure. Really the proper torque values for those suckers is a lot lower than you'd think:
http://www.tirerack.com/wheels/tech/techpage.jsp?techid=107

Too bad for your friend.  I hope he heals well.  I know this kind of stuff can spook a person bigtime but you have to climb back on the horse.   [moto]  He can thank his lucky stars that it didn't hit him directly and that it wasn't any bigger.

Not that I want to scare your buddy or anyone else, but unfortunately this type of thing is more common than you might think.  We had a rash of wheels coming off transport trailers a few years ago in this part of the world.  A few caused some horrendous injuries and deaths to both car drivers and pedestrians.  An investigation showed most were attributed to under (or over) torquing, worn out bolt holes and a few to a shipment of sub-standard wheel studs from somewhere in Asia.  There is now actually a government certification course required for truck wheel installers.

I personally witnessed one such event.  Lucky for me I saw the oncoming wheel and I was able to watch it smash into the wall of the building I was sitting in and then bounce off again in another direction!

This poor guy wasn't so lucky.

http://www.youtube.com/watch?v=s7BJrUOzUh4

Here in the UK, I have noticed many trucks fitted with these, the driver checks them on his 'pre-flight' inspection.



http://www.tyre-rite.co.uk/detail.aspx?ID=206

  wow...

hope your buddy feels better soon!
check your tires gang!

My brother was hit by an oncoming tire in his pickup truck about ten years ago.... bounced right on up into his windshield and totaled it.

Sounds like a scene from a movie doesn't it?



Ext. Country road- Day

A small pickup drives past a fruit stand. 

Int. Pickup- continuous

The driver fiddles with the radio station, settling on a country song, something old, maybe by Willie Nelson.

Close-up Drivers face as panic wipes across it.

Drivers POV as a tire skittles off of an oncoming car, bounding into his lane and in SLOW MOTION smashing through the windsheild!

Cut to:

Ext. Country road - moments later

The pickup is halfway into a strawberry field, the driver looking at it with a look of ocnsternation.  The driver from the newly re-engineered tricycle runs over.


Truck driver lays him out.

The end.

That could have happened to me.

A mechanic once forgot to tighten the Lug Nuts on the front left tire of my car.  When I got off the freeway, I heard a strange bumping noise so i pulled over.  3 of the 5 Lug Nuts had fallen off and the remaining two were barely hanging on the threads.  It seemed like they just finger tightened it and forgot to use the impact wrench.

I took a lug nut off of two of the good tires and used it to get to the nearest parts shop.  Disaster averted!