You want new wheels. We want new wheels. But do the wheels you want actually fit your vehicle? There are several factors to consider, the first being the bolt pattern of your wheels. Even if you get a wheel with the proper backspacing and right diameter to match your tires, none of that matters if you can't bolt them onto your 4x4. The number of lug studs and the bolt circle, such as 5x5.5 or 8x170, designates the bolt pattern. Note that both inches (5.5) and millimeters (170) are used to express the distance of the bolt circle. If you have an even number of lug studs the math is easy, you measure from the center of one stud to the one directly across from it. If you have an odd number of lug studs though the math gets hard, as you measure from a stud to an imaginary line between the two opposite studs. This gets particularly tricky since five-lug wheels are available in a variety of bolt circles including 5x4.5, 5x5, and 5x5.5. Telling them apart just by looking at the bolt circle can be daunting.

What Bolt Patterns Tell Us

A wide variety of bolt patterns exist, from the tiny 4x100 Geo Metro bolt pattern up to the huge 8x180 pattern on new GM trucks. More lug nuts providing more clamping power to hold the wheel onto the vehicle. Consider that you can quickly tell a half-ton truck from a one-ton truck because the half-ton truck will have five or six wheel studs and the one-ton truck will have eight wheel studs. Additionally, the larger bolt circle not only distributes the load over a wider area but also allows for using a bigger hub and bearings.

Wheel Studs

So we have established that more lug studs are better, and a wider pattern is better, but what about the lug nuts themselves? The basic factors related to wheel fasteners include:

- Thread diameter
- Thread pitch
- Thread length/thread engagement
- Seat type

In SAE sizing, a 1/2x20 size has a 1/2-inch diameter and 20 threads per inch. In metric sizing, a 14x1.5 has a 14mm diameter with 1.5mm between the threads. So a larger number for thread pitch means a finer thread with SAE sizing, but a courser thread pitch for metric sizing. Installing larger studs is one way to increase the clamping force and strength of the connection between your axles and your wheels. But your wheel must have big enough holes to accommodate the larger studs.

Lug Nuts

Lug nuts seem simple enough, but there is quite a bit of variability with them beyond just size. Having the proper lug nuts for your specific wheels is absolutely critical. The "seat" refers to the shape at the base of the lug nut where it contacts the wheel. The most common seats for aftermarket wheels are conical, although there are some radius seats. Flat seats aren't uncommon on factory wheel offerings and are sometimes found on aftermarket wheels as well. The reason conical seats are the most common is that they are less dependent on hub register and lug stud size, allowing one wheel to fit more applications.

Lugcentric or Hubcentric

To run true wheels must be centered on the axle hub via the lugs or the hub. If the wheel registers via the center bore, it is considered hubcentric. These wheels are more common in OEM wheels than aftermarket wheels designed to fit a variety of applications. Lugcentric wheels, where the studs are used to center the wheel, are far more common in the aftermarket. With lugcentric wheels the size of the lug holes in the wheel should closely match the lug size on the vehicle to ensure the best fitment.