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Since I already have two 1/4″ torque wrenches for bicycle work (click style; 20 Nm and beam style; 9 Nm), I am hoping that my 3/8″ torque wrench (Beam style; 90 Nm — 800 inch.pound) would be adequate for car wheels.

3/8″ torque wrench beam style; 90 Nm; 800 inch.pound

Will a bicycle's torque wrench double for use on car wheel lug nuts, despite that the requisite torque (usually 70 to 90 Nm) is at the top of the range?

Another issue is the confirmation of a torque after some time has passed.

It is generally considered unsafe to retorque critical parts on a bicycle (cranks and hubs) without first unscrewing. The idea (which I don't understand very well) has to do with the cumulative torque being potentially unsafe.

Does this convention carry over to lug nuts? Do I need to first unscrew and then retighten after the usual 500 km on a newly installed set of wheels? One potential big difference may be that bicycle bolts are almost always greased before torquing, whereas lug nut torques are specified as dry torques.

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Unfortunately no, your small torque wrench would not do the job. Steel wheels usually call for 80 lb ft (108.5 Nm) of torque to secure them. If you're talking alloy wheels, it would be 100 lb ft (135.5 Nm). I'm not sure about exotic wheels like carbon fiber, so can't tell you what they should be torqued to.

As far as retorque, it's usually a good idea to do this on wheel lugs. Don't untighten them, just retorque them. Give the wheels a couple of days of travel, then go for it. To do this, just go back around and test how tight they are at the final torque value and call it a day. I usually do my torquing sequence in two steps to ensure they are torqued equally is why I mention "final torque value".

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  • It should be added that torque - especially on dry bolts - is not an accurate process. ±25-35% is a commonly seen value. Re-torquing if bolt is close to desired value is unlikely to change anything, as it won't overcome static friction...
    – vidarlo
    Commented Dec 19, 2023 at 9:17
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    @vidarlo - I have a hard time believing the source you provided as far as torque being off by ±25% to ±35%. Usually, when a source says there's a "consensus" without any source to back it up, it's more like internet mumbo-jumbo and is meaningless. Yes, a torque value is less accurate than bolt stretch, but there's no easy way to measure bolt stretch at home in the driveway. Retorquing a lug is done to ensure any of the "variance" hasn't caused a lug to become loose or looser than any of its pals in the hub. It is strictly a safety concern.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Dec 19, 2023 at 11:39

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