lug nut torque question

Ok, this is a somewhat stupid question.
Do you torque the lug nuts according to the specs for the car they are on? or to the specs of the wheel?

to clarify, if you are using wheels from a 240sx on your accord, do you torque to the accords specs or the 240sx specs?
I am leaning towards the cars specs, but just wanted to double check myself.

car specs definitely makes the most sense.

The specs of the lugs (car), unless the wheel is a different material of construction. Steel wheels, aluminum wheels, mag wheels, etc. all need different torques. Additionally, the type of lugnut matters. If they are acorn shaped, or have a larger surface contact area the torques would also be different.

Or, you could just lean on the air wrench for a few minutes, like they do at the tire store.

Good question, and I don't know for certain.

My first thought would be to go with the car's specs, like shuttlepilot says, because that's what fastener would be involved (if there's a difference in lug diameter or pitch).

OTOH, if the lug seat type is different (angled vs spherical, etc), does that have an effect? Wheel material?

My $0.02, based on nothing but logic:

Torque is a relationship between two parts of a threaded fastener, in most automotive cases, a stud and a nut.

That's it, nothing else. Not the wheel material, not the thickness of the wheel, the seat type, or your mother's underwear size.

A 1/2"-20 lug nut on a 1/2"-20 stud requires (x) ft.-lbs. of torque. Could be a Volvo on steelies or a Dodge on aluminum rims, does not matter.

So to answer your question, use the torque specs for the CAR.

Torque them down till they strip, then back them off half a turn.

For what it's worth, if the owner doesn't have a preference and doesn't know OEM specs, we torque to 100lb-ft. Rarely had a problem with that as a rule of thumb.

EvanR wrote: A 1/2"-20 lug nut on a 1/2"-20 stud requires (x) ft.-lbs. of torque. Could be a Volvo on steelies or a Dodge on aluminum rims, does not matter.

That X torque value listed on a chart is the value of maximum torque value for maximum clamping force. It is not, and has never been, a required torque.

Go over it and you get into plastic deformation and failure of the threaded pieces. Go under it and you simply have less clamping force.

If you have a soft alloy wheel and use a steel rim torque value, you will likely end up deforming the wheel. This is not a good thing. This is why some wheels come with specific torque instructions.

ok, so lots of confirmation on my thoughts. guess I'll stick to using the cars specs on the new wheels.

I use the specs for the fastener. I don't want to overtorque the fastener, causing bolt stretch and/or shearing it.

m

I agree with evanR.
Found this in one manual. Steel wheels , 66-87 lb/ft, Alloy wheels ,75-105 lbs/ft I always did mine at 75-80 lb/ft and never had a problem.

iceracer wrote: I agree with evanR. Found this in one manual. Steel wheels , 66-87 lb/ft, Alloy wheels ,75-105 lbs/ft I always did mine at 75-80 lb/ft and never had a problem.

Your thinking is like mine. There may be people with wider experience who can shed some light on it. But all the torque specs I've been exposed to have a range and somewhere in there is a lot of overlap. I set the wrench for 80 ft. lbs. when I'm doing lug nuts. I've never had a problem.

Oh, and it's worth putting a dab of anti-seize on there from time to time if you change them a lot.