Wheel Offset and Backspacing Explained
August 30, 2021
With so many different numbers and measurements on wheels, it can be a little confusing to understand.
If you've been looking for new wheels for your vehicle, you've probably come across the term Offset and Backspacing quite often. But what does it really mean and does it matter? We'll go over all of those questions and more.
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Before we get into the nitty-gritty details, wheel sizes are normally listed as 22x12 -51mm or 18x9 +25mm, etc, but what do all of these numbers mean? First, we have the wheel diameter which, in this example, is a 22. So a 22x12 -51mm would be a 22" diameter wheel.
The second set of numbers listed is the width in inches, so a 22x12 -51mm would be a 12" wide wheel. The third set of numbers is where it gets tricky. That number is the offset of the wheel in millimeters. So a 22x12 -51mm would be a -51 millimeter offset.
What Does Offset Mean?
So there's wheel diameter, wheel width, and a "positive" or "negative" offset.
What is offset? Offset measures the distance in millimeters (mm) + or - from the hub (where you bolt the wheel to the vehicle) to the true center of the wheel.
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A "negative" offset is where the mounting surface of the wheel is closer to the inside (brake side) of the wheel. In the truck world, many custom truck wheels come in aggressive negative offsets.
The more negative the offset, the more aggressive stance you will get.
This means the wheels will "poke" outside of the fenders. "Poke" or "Stance" is when the wheel and tire stick outside of your fender. A negative offset is what can create a larger lip or concave style which will push the tire out.
Here are some other blogs you might like...
- Read: Everything You Need To Know Before Buying Wheels and Tires
- Read: Is It Safe To Lower Your Car?
- Read: The Best Wheel And Tire Packages For Cars
- Read: Top 10 Wheel And Tire Packages For Trucks
On the other hand, a "positive" offset is where the mounting surface of the wheel is closer to the outside (fender side) of the wheel. This pushes the wheel in toward the brakes which can "sink" the tire and wheel into the fender well opening.
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What Is Backspacing?
Does backspacing matter? Backspacing is similar to offset, but it changes where we measure from. We are still looking for the distance from the mounting surface of the wheel, but instead of measuring the centerline, it's measured from the back edge of the mounting surface (hub).
Backspacing is less commonly used than offset because offset has replaced backspace measuring in common wheel fitment.
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When you break it down, offset and backspacing aren't too difficult to understand and play a big role in the way your wheels fit and how they look.
If you head over to our homepage, you'll be able to enter the year, make, and model of your vehicle and find wheels that we recommend for your specific vehicle. This will make your wheel fitment decisions even easier!
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