Bolt Pattern Basics
Every vehicle rolls off the assembly line with wheels designed to its exact specifications. And, since your stock wheels are perfectly crafted for your vehicle, there’s no such thing as a one-size-fits-all rim. In order to find a set of rims with an accurate fit, you have to know a few measurements: the desired diameter of your new wheels, the desired width and offset and the specific bolt pattern required. Here we'll focus on the bolt pattern. The bolt pattern (or lug pattern) is comprised of two numbers. The first indicates how many bolt holes are on the wheel and the second describes how far apart the bolt holes are from one another across the diameter of the wheel. For example, 4 X 100mm is a wheel with 4 holes total, spaced 100mm across from one another when measuring from the center of each lug hole. More on this below.
Measuring Your Bolt Pattern
Wheels with 4, 6 and 8-bolt patterns are measured from the center of one lug hole to the center of the opposite hole. Wheels with a 5-bolt pattern are measured using the diameter of a circle that crosses through the center of the lug holes. Measuring a 5 bolt pattern is very difficult and not recommended to confirm wheel fitment without using a bolt pattern gauge. Below are examples of measuring 4, 5, 6 and 8 Lug wheels
Millimeters vs. Inches
Both millimeters and inches are used to measure your wheel bolt pattern, sometimes interchangeably. Either way, it’s essential to be as exact as possible when determining your wheel lug pattern since a few millimeters can mean the difference between a wheel that fits your car and one that doesn't. Looking up your specific application online is usually the easiest method, but physical measurement always adds piece of mind. Investing in a bolt pattern gauge makes the process as simple and accurate as possible. Many wheels might only be listed in mm, while others exclusively in inches. It's important to know what the equivalent measurements are for either to make sure you are looking at all the possible wheels that fit. For example, you might lookup your wheel at a measurement of 4 X 114.3 MM. The equivalent measurement in inches is 4 X 4.5". Some sites only list one method of measurement, but not both, so knowing your bolt pattern equivalent makes it easier to shop for all the possible wheels that will fit your vehicle. See below for a complete bolt pattern conversion chart for millimeters to inches, and vice versa.
Bolt Pattern Guide
A common example of a bolt pattern measurement is 4 x 100mm or 4 x 3.94". While the second number in these measurements may look hugely different, the only difference is the use of millimeters vs. inches, these are actually the same exact size bolt pattern. This can be confirmed by the basic conversion factor: 1 inch = 25.4 millimeters.
The first number in a bolt pattern measurement (e.g., the '4' in (4 x 100mm) or the '5' in (5 x 4.5") represents the number of bolt and lug holes in each wheel. The most common lug hole numbers are 4 or 5, which are typically used for sedans or coupes, while larger vehicles like SUVs and trucks generally have bolt counts of 6, 7 or 8.
The second number of a bolt pattern measurement for example, the '100' in (4 x 100mm) or the '4.5' in (5 x 4.5") represents the bolt circle diameter or BCD (Which is the same as PCD or Pitch Circle Diameter). The BCD figure is measured by connecting the dots created by a wheel's lugholes to create a perfect circle. The circle must pass perfectly through the center of each bolt or lughole in order for the measurement to be accurate. Once the circle is drawn, real or imaginary, you measure the diameter of the circle. The figure derived from this measurement is the bolt circle diameter – which is the key measurement in a wheel bolt pattern. In simple terms, it's the distance from the center of one lug hole to center of the other (most opposite lug hole), measuring across the center of the wheel. The exception being a 5 lug pattern, which varies only slightly.
If you take one thing away from here, take this: even the slightest discrepancy in measurements can mean the difference between a sweet upgrade and a serious dilemma. Consult our handy lug pattern chart to make sure you have the process down pat and take advantage of our lug pattern conversion chart to keep your math to a minimum. Once you’ve got the right set of numbers, AutoAnything has an incredible selection of wheels and lug nuts in varying sizes, styles and materials to choose from.