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Hummer Knowledge Base

The Hummer Knowledge Base

Tires & Wheels/Lug Nuts:

> Simple question please: What is the correct torque for the lug nuts?  Does
> anyone actually measure it or is it safe to just crank them on really
> tight?
> Thanks,
> Joe Neely 1997 OT

Joe (& all):

Following information is for the tapered lug nuts used on the two-piece wheels. I am not familiar with the one-piece specs, but the lug nuts are quite different, and not interchangable.

The correct torque specification is: 110 lb-ft

If you over-torque them by as little as 10 lbs, you will crimp the tapered end, and turn them into lock-nuts (i.e. hard to turn for the entire removal). They will still work, but you will need air tools to change the tires (or perhaps 30 minutes each, many teen-agers, etc.)

Dave Breggin
'95 Diesel Wagon

For single piece wheels, the correct torque specification is 140 lb-ft.

Sidebar: Always check the torque after anyone does any wheel work for you and you are not able to watch to make certain that the nuts are torqued correctly. If you have two-piece wheels, and a dealership last worked on the wheels, they will have most likely been torqued to 140 lb-ft. instead of 90-110 lb-ft.

Mark L. Gaubatz
1995 Silver Hummer

Dave and All:

The lug nuts on the one-piece rims have a flat bottom and the 2-piece are acorn.

Gary Collings
95 white wagon

ATTENTION! There are TWO TYPES of one-piece wheel made by AMG. Prior to 1997, the one-piece rims used ACORN lug nuts.

From 1997 on, the new one-piece rim uses a flange nut very similar to the rim nuts used on the two-piece rim sections.


If you look at the mounting holes in the rim, you can easily tell which is which.

A rim which uses ACORN lug nuts has TAPERED HOLES, wider on the outside of the rim, tapering at an angle matching the taper on the lug nut to a smaller diameter on the inside of the rim.

A rim which uses FLANGE NUTS has STRAIGHT-BORED HOLEs which are the same diameter throughout. Note that the holes are actually punched, so they may not be perfectly smooth, like a drilled or bored hole, but they are NOT TAPERED holes.

Also, the holes on the rim appear to be slightly smaller in absolute diameter, which means a closer fit on the studs. This is because the flange nut is not self-centering like the acorn nut is. The acorn nut actually sticks almost through the rim when tightened, so the hole in the rim is just slightly larger overall. The flange nut wheel must have a closer tolerance to the stud so that the wheel will align properly and not go off-center.

Know thy Truck!

The lug nuts on the Hummer are compressed to produce a resistance thread. They required full force of your air gun, the full travel of the bolt, to get them off. My little compressor needs many moments to catch up with air pressure. This issue is really a pain when you are out in the field.

Anyhow, the lugs are 9/16 -18R thread, 3/4 height, acorn sleeve in case you what to change them. BTW the torque on the lugs is 100 lb. They should be about 60 cents each. NAPA has them. They are on a 74-86 Wagoneer , 91 suburban and some 3/4 ton and above trucks. Better to get them in galvanized (if you can find them) or stainless (if you want to pay $5/ lug).


>My wheel lug nuts are very tightly threaded or so they seem to be.  For
>instance when I reinstall  a wheel I turn the lug nut about 3 full turns
>by hand after that you need a lug wrench or a impact gun.  I have a 650
>ft lb impact gun and a 6.5 HP compressor and it strains this gun.
>Meaning it does not just zip these lug nuts of.
>Is this normal ?
>Thank You

Normal? No. Common? Yes!

Your lug nuts were over torqued, replace 'em and all will be 'normal' again (until they get over torqued again!)

Peter Hipson
Founder New England Hummer Owner's Group (NEHOG) the free Hummer Owner's group!
1995 White NA Hummer Wagon


Absolutly not normal!

This is caused by over-tightening of the lug nuts. They should be tightened to 110 lb-ft, not more. Most vehicles using lug nuts this size accept more torque before damage occurs. Therefore, many techs over-tighten them without even realizing it.

The tech at my dealer has seen Hummers direct from the factory with over-torqued lug nuts. This is quite a common problem.

It is rare that this problem causes damage to the lugs themselves (i.e. the studs on the hub). Inspection is called for, however.

Dave Breggin
'95 Diesel Wagon

Lug nuts should be snug but not difficult to hand turn, but they do "stretch" after being torqued a few times which can make them very tough to get on and off (especially with a manual the field), and it's a good idea to replace them at regular intervals.

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