The 2 most common lug nut sizes for semis are 1 1/2" and 33mm. 33mm are offered in both Push-On and Thread-On. Use this guide to help determine which size and type will fit your lug nut.
Step 1: Determine your lug nut size
Grab a 33mm socket and place it over your lug nut. If it fits snug into place and is not loose or able to spin, then your size is 33mm.
(The same applies if you are using a socket that is 1 1/2". If it spins freely around your lug nut, 1 1/2" is too big and you will most likely need 33mm or something smaller.)
Hub Piloted VS Stud Piloted Wheels
If you have 33mm lug nuts then you most likely have a hub piloted wheel.
If you have 1 1/2" lug nuts then you most likely have a stud piloted wheel.
A stud piloted wheel will never have a lug nut with a flange at the base.
Step 2: Do you need Push-On or Thread-On?
To figure out if you need Thread-On or Push-on, just take a look at how much thread you have. If you have at least 1/2" of thread, you can use a Thread-On lug nut cover.
Anything less than 1/2" of thread will require a Push-On.
Step 3: Find your new lug nut covers!Now that you know what size and type you need, you're ready to start customizing your truck's wheels.