I am putting a set of FX4 wheels on my 97 XLT. My searches for information on the proper lugnuts has been disappointing. My stock lug nuts are flat and I believe 12mm studs. The later model FX4 wheels (2002) are for 14mm studs and there appears to be a slight taper on the wheel hole. There is definitely a gap in the diameter of the wheel stud versus the diameter of the wheel hole. Any ideas?

 

Best way to find out is to call your local dealer and get someone from the parts department. Give them your VIN and then ask that question.

 

My 2003 FX4 wheels do not have any taper to the wheel nut holes. They use a lugnut with a flat washer attached to the bottom. I just had the fronts off to do the the brakes over the Christmas holiday.

http://www.rockauto.com/catalog/rafr...rttype=7676&ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=CAD&ck[PHP_SESSION_ID]=dbelh31r0fmkg22d09e5vovk34

Mine look like the Dorman 611206's more or less.

I am not sure if the 2mm makes much difference. The wheels are hub centric. Many people with older trucks have upgraded their wheels to the FX4 ones and I doubt they have changed out all the studs.

 

You'll need to measure your studs.
If they are 12mm they will be under 1/2" (.472) or about the 1/32 larger then 7/16"

If they are the larger 14mm the will be bigger then 1/2" (.551), or just a touch smaller then 9/16"
then get the corresponding lug nut for the desired rim

 

If the wheels require tapered lug nuts then you'll need 12mm tapered lug nuts, if they don't, then just reuse the lug nuts you have now. Regardless, you'll still use 12mm lug nuts.

The stud size only affects the lug nuts you use, it doesn't make a difference on what wheels you can use. Like grizzstang said, nobody is going to change out their studs just to run the FX4 wheels. Think of it this way, if you're looking at aftermarket wheels for these trucks they don't make you specify between 12 or 14mm studs.