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Wheels may look like glorified circles, but in actuality they are very complex devices that require high-tech, precision engineering processes to ensure that they do their job.  Furthermore, millions of dollars are spent every year by original equipment manufacturers like BMW, Lexus, Audi, Jaguar, Porsche, Ferrari, Infiniti and so on to make sure that every single wheel they put on a car, truck or SUV is durable, dependable, and even stylish.

So what makes up a wheel?

Here in Wheel Tech 101, we'll go over the most basic elements of a wheel: its measurements.

Width and Diameter

These two are pretty obvious, so we won't spend much time on them.  Suffice it to say, a wheel designated as 17 x 8 is a wheel that's 17 inches in diameter and 8 inches wide.  Those particular measurements might be found on any BMW 3-series, a Jaguar S- or X-Type, Jeep Grand Cherokee SRT8 or Wrangler Rubicon, or a Lexus SC300 or IS250.  And probably a bajillion other vehicles, too.

Offset

Wheel offset is simply the distance from the mounting surface of the wheel to the true centerline of the rim.  It's something that's actually pretty hard to measure without some precision tools, but it's not impossible.  Offset comes in positive and negative numbers:

• Positive offset is closer to the fender well, and means the mounting surface is positioned IN FRONT of the true centerline
• Negative offset means the wheeel will stick out away from the vehicle, because the mounting surface is BEHIND the centerline of the rim assembly

Bolt Pattern

Bolt patterns are usually written like this: 5x112.  The first number (the "5") is the number of bolts that go on the wheel (typically 4, 5, or 6).  The second number is the pitch circle diameter, which measures the diameter of the bolt circle...which, interestingly enough, means different things based on how many bolts the vehicle has.

For 4- and 6-bolt wheels, you're measuring from the center of one bolt hole to the center of the bolt hole directly across from it.  A 5-bolt wheel requires a little geometry: mentally "draw" a circle running through the centers of each bolt hole, then measure from the center of a single bolt hole out to the imaginary circle that lays between the two opposite bolt holes.

Center Bore (a.k.a. "Hub Bore")

These two terms are synonymous, and measures the center hole in the wheel.  This hole is used to center the wheel on the car's hub.  Pretty simple, eh?

Mass production of wheels means that large center bores are common, so if you are trying to fit one type of BMW wheel on a different model of BMW, you might need to use something called a hubcentric hub ring to prevent or eliminate any vibration or noise caused by there not being a perfect fit.

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For more info:

• Read even more about wheels in Wheel Tech 102: Wheel Construction!
• More articles about Wheel Fitment

Did this article help you?  Did we miss anything, or mess something up?  Let us know in the comments below, or by contacting us!

A wheel has a rim and when someone says "rim" they often mean "wheel."  Wheels and rims, rims and wheels.  It can be confusing, but really, they are pretty much synonymous with one another unless you're talking to an engineer or technician about something very specific.

But whether you call it a "wheel" or "rims," the manufacturing process is very, very important, because it sets the baseline for durability, weight, strength, and appearance.

Alloy Wheels vs. Steel Wheels

Pretty much every OEM wheel you're going to find is made of an alloy composed of aluminum and other metallic substances.  Alloy wheels are more durable, stronger, and better looking than a steel wheel.  Durability means less of a chance of cracking or corroding under normal conditions, strength means longevity, and appearance means style.  Alloys are also lighter than steel, which directly leads to responsiveness, handling, and acceleration.

One-, Two-, and Three-Piece Wheels

The vast majority of wheels are one-piece wheels, which means they were manufactured using a single mold.  Some wheels come in two- or three-piece versions, wherein there are multiple pieces molded separately (a center and barrel, or a center, inside, and outside rim pieces, respectively) and are welded and/or bolted together using high quality fasteners to ensure there's no separation.

Forged Wheels

Forged wheels are stronger and lighter than your standard aluminum wheel, because they are subjected to forced compression combined with heat.

Roll Forging

A subset of forging, roll forging sees the use of a metal blank run through rollers.  Less aluminum is used in this process, which reduces the weight of the wheel (increasing performance), but maintaining its strength and durability.

Low Pressure and Counter Pressure Casting

Low pressure casting is the most common form of wheel manufacturing currently used.  This is simply the act of pouring liquid metal into a mold and cooling it to harden into its final shape.  Counter pressure casting instead sucks the metal into the mold using a vacuum rather than having it poured in, which reduces impurities and increases material strength of the wheel.

Lug Nuts, Lug Bolts, and Wheel Locks

Though not a physical part of the wheel during the manufacturing process, lug nuts and bolts are absolutely integral when considering the durability, strength, and appearance of your wheels.  Bolts come in three common types:

• acorn seat (conical)
• ball seat (radius)
• mag shank seat

When you are going with aftermarket or replica wheels, you may not be able to use your OEM lugs, which immediately calls into question the fitment and durability of any such wheels.  With OEM wheels, your OEM lugs (or lugs that are considered "OEM replacement lugs") can be used, ensuring proper fitment and safety.

In Conclusion...

...wheel construction is a very important consideration for any vehicle owner, and it's why L.A. Wheel and Tire only deals with OEM wheels.  Original equipment manufacturers (O.E.M.) like BMW, Lexus, Mercedes-Benz, Jaguar, Audi, Honda, Dodge, and everyone else have been making OEM wheels, lugs and hardware for a very long time, and spend literally millions of dollars every year on safety and durability tests.  Knowing that you are getting the best, highest quality product is very important to us, and hopefully this crash course in wheel construction lets you know that we take that dedication to you very seriously.

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Was this informative?  Let us know in the comments below!

For more info:

• Read our article on Wheel Tech 101: Measurements
• Read more articles about Fitment