How to Torque Lug Nuts Properly

February 10, 9:33 PM [GMT -5]

Charlie, Thanks for the feedback and your experiences.  I too, went many years tightening lug nuts without use of a torque wrench even though I owned one and was employed at the time as a service technician in the farm equipment business. Until the last few years, if a person was careful and did not use too large of breaker bar minimal, if any, damage would be done particularly if the vehicle was equipped with steel wheels.  However, with newer vehicles, the brakes rotors seems to be more susceptible to warping when over-torqued and the potential for damage to an alloy wheel when either under-torqued or over-torqued is much greater. The price of one damaged rotor or especially an alloy wheel more than offsets the cost of a torque wrench in my humble opinion.

You are correct some tire shops and garages still rely on the trusty old impact wrench and the technician's 'feel.'  That’s one of the reasons why I always check my lug nuts after it has been to a tire shop.  I want to be sure I can remove the lug nuts with the OEM furnished tire tool in an emergency as well as verify proper torque.  However many shops and technicians today use a torque limiting tool, which while looking like an impact, utilizing a torsion torque bar  that limits the maximum amount of torque applied. Snap-on Tools (site links below) is one manufacturer, but there are many others. I used various versions in a manufacturing environment beginning over 20 years ago.  I also worked as a quality technician responsible for torque tooling and practices for about 4 years.  It gave me a whole different understanding about the importance of proper torque. I know personally, I’ll always check and use a torque wrench for lug nuts just as I would for a connecting rod, cylinder head or other critical components.

http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=81389&group_ID=1649&store=snapon-store&dir=catalog

http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=78290&group_ID=2219&store=snapon-store&dir=catalog

February 07, 8:40 AM [GMT -5]

Good info.  I would have to add that most tire and repair shops, at least every one I've been to and can think of, don't bother to torque lug nuts.  I think that the majority of them just run the lug nut down with the impact gun.  I can also say that in my 22 years of driving and maintaining my own vehicles, I've never used a torque wrench to put on my lug nuts, and I've never had a problem with it. 

February 04, 9:42 PM [GMT -5]

A good basic reminder about proper torque procedures for lug nuts. Realistically, though, few if any folks carry an adjustable torque wrench in their vehicle. Hopefully most will have the vehicle, factory provided lug wrench. The procedure for using one of those is the essentially the same with the major difference being you don't know exactly how tight you are getting the lug nuts. In an emergency situation e.g. changing a flat tire, just make sure are tightened securely using the factory provided wrench. If you do not own a torque wrench, then seek out a garage or tire shop to properly torque the lug nuts.

While the article correctly noted do not overtorque, it is extremely important to note any fastener can easily be overtorqued when using an adjustable, 'click-type' torque wrench if not used properly. When using an adjustable, click-type torque wrench, they are typically designed to slightly break over center and provide an audible click when attaining the preset torque value. Once the tool clicks, STOP. DO NOT click additional times. Doing so only applies more torque even when the tool breaks over center and clicks.

An additional note when using a adjustable click-type torque wrench to recheck or verify a fastener is properly torqued, you should first loosen the nut or bolt, then retorque to the desired torque value. This accomplishes two purposes (1) You will not overtorque a fasteneer that may be correctly torqued (2) Verify the fastener is already overtorqued.

Lastly, many vehicles today have aluminum or alloy wheels. I have found it is a good practice to check lug nut torque on these types of wheels at every oil change. Again, always loosen the lug nut first and then torque to the manufacturer's specification using the 'star' or criss-cross pattern shown in this article. I highly recommend rechecking torque on any wheel which has had the lug nuts removed within 50-100 miles of the service. Unfortunately, on numerous occassions, I have found one or more lug nuts loose from a repair shop. Many tire shops request or require you to return for this service and provide it free.