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retorque lug nuts after tire change

Why is it necessary to retorque your wheels after a tire change? We never had to do this in olden days. I already have enough superstitions, I don't want to take on a new one for a one in a million problem.
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Comments

  • edited November 2010
    My guess is the lawyers. If the shop fails to tighten the lug nuts fully and a wheel falls off, they can point to the need to retighten to try to weasel out of responsibility. Just a theory . . .
  • edited November 2010
    If you completely trust the place that installed the tires then you don't necessarily need to. One problem is that the wheels are supposed to be torqued to a particular specification and uneven lug nut torque and over or under torque can create real problems with, for example, your brake rotors. A lot of shops just whack the lugs back on with an impact. Out of that you normally get too much torque and uneven torque.

    On anything but steel rims it is also the case that the torque specs tend to be on the low side. After its been driven a while its a good idea to make sure that they are still all torqued to spec.

    If you don't have a torque wrench though then there isn't much you'd be able to do with it other than make sure that none are loose.
  • edited November 2010
    There are a lot of things that can go wrong when tightening up lug nuts - a piece of grit between the hub and the wheel, un-even centering - and the purpose of retorquing is to make sure the lug nuts are tight enough to hold the wheel on. Even if it is a one-in-a-million, a wheel falling off can cause all kinds of bad things to happen.

    The lug nut seats on steel wheel act like springs, so they do a better job of retaining their torque if the wheels settles into a different position.

    If you are doing it yourself, then it should be obvious that it doesn't take long to do.

    If you are not doing it yourself, then take the safe route - either learn to do it yourself or return for the retightening.
  • edited November 2010
    It shouldn't be necessary, but checking the work yourself is always a good idea. I do it because I don't want my wheels to fall off because they are under-torqued, and because I don't want my brake discs to warp because they are over-torqued. I have had too many instances where work was performed on my motorcycle, and something wasn't properly torqued. It is great to have a trailer so I can pick-up my bike without having to ride it home.
  • edited November 2010
    My local tire dealer recommends a retorque after 100 miles...apparently a wheel came off a car several years ago and I guess they are taking no chances. See recent and related post about two tires coming off.
  • edited November 2010
    I loosen and re-torque every time it is in the shop for anything, even state inspection. There are times I have had to resort to a 5 foot "cheater pipe" to loosen them. I don't want a flat tire on the road, where I don't have a five foot pipe. You would be amazed at how easy it is to loosen lug nuts that are torque to 100 ft. pounds, even after a year.
  • edited November 2010
    Here's a great reason to retorque: http://community.cartalk.com/posts/list/2161796.page
  • edited November 2010
    It could be partly a CYA issue. I bought new tires installed on new wheels at Costco. They told me to come back in a week for a free re-torqueing of the studs. Costco does not take any chances with someone wanting to sue them if something happens to the car's wheels.

    Having said that, if the wheels are new they may need a certain amount of adjusting as the studs seat themselves.

    Strangely, when you buy a new car, there are no instructions to go back to the dealer for a re-torqueing.
  • edited November 2010
    "We never had to do this in olden days."

    Were you rolling on aluminum alloy wheels in the olden days?
  • edited November 2010
    I'm now thinking of the time had had to use a 3' breaker and literally jump on the thing to break it loose - for only 1 out of 4 lugs. This was the same day I returned from a shop.

    Every time I take a car in now I have "Torque lug nuts to xx lb." written onto the service order. So far that works. (I can't tell if the tech is being snide when he writes "torqued lug nuts by hand...")
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