Wheel Offset Vs Backspacing

5 Mar 2024
Wheel Offset

Wheel Offset Vs Backspacing


Wheel offset and backspacing appear similar, but they play distinct roles in determining the positioning of your vehicle’s wheels. Backspacing measures the distance from the wheel’s mounting surface to its inner edge, while offset indicates how the wheel aligns with the centerline. It’s worth noting that backspacing is measured in inches, while offset is measured in millimeters. These measurements decide whether your tires will sit inside or extend beyond the vehicle’s frame.

Understanding wheel offset and backspacing is essential for ensuring the perfect fit, style, and performance of your vehicle. In this guide, we’ll understand the intricacies of wheel offset vs backspacing, their details, and how they are measured.

What Are Wheel Offset and Wheel Backspacing?

First, let’s understand each of these terms individually.

What Is Wheel Backspacing? 

Wheel backspacing refers to the distance from the mounting surface of the wheel to the back edge of the wheel. It determines how much space there is between the back of the wheel and the suspension components inside the wheel well. This measurement plays a crucial role in ensuring proper fitment of wheels, especially when it comes to avoiding interference with brake calipers, shocks, or other suspension parts.

What Is Wheel Offset? 

Wheel offset, on the other hand, refers to the distance between the centerline of the wheel and the mounting surface. It determines where the wheel sits relative to the hub and the fender of the vehicle. A positive offset signifies that the mounting surface is positioned nearer to the front face of the wheel, whereas a negative offset indicates its closer to the back face. 

Difference Between Wheel Offset and Backspacing

Measurement Basis:

Wheel Offset: It is measured concerning the centerline of the wheel.

Backspacing: It is measured from the mounting surface to the back edge of the wheel.

Position Determination:

Wheel Offset: Determines the position of the wheel mounting surface relative to the wheel’s centerline.

Backspacing: Determines how much space there is between the back edge of the wheel and the mounting surface.

Unit of Measurement:

Wheel Offset: measured in millimeters (mm).

Backspacing: measured in inches.

Impact on Fitment:

Wheel Offset: Affects how the wheel sits in relation to the vehicle’s body and suspension components.

Backspacing: Influences the clearance within the wheel well and ensures proper fitment without interference.

Considerations for Installation:

Wheel Offset: A positive offset indicates that the mounting surface is closer to the front face of the wheel, while a negative offset suggests it is nearer to the back face.

Backspacing: Larger backspacing pushes the wheel further into the wheel well, while smaller backspacing brings it closer to the vehicle’s outer edge.

Aspect Wheel Offset Wheel Backspace
Measurement Offset measured in Millimeters (mm) Backspacing measured in Inches
Calculation Method The distance from centerline of wheel to hub mounting surface The distance from the back of the wheel to the hub mounting surface.
Inward Position Positive Offset Higher Backspace
Outward Position Negative Offset Lower Backspace


Wheel Offset Vs Backspacing Chart 


3.25″ 3.50″ 3.75″ 4.00″ 4.25″ 4.50″ 4.75″ 5.00″ 5.25″ 5.50″ 5.75″
5.5″ 0 +6mm +12mm +18mm +26mm +30mm +36mm +42mm +48mm +54mm +60mm
6.0″ -6mm 0 +6mm +12mm +18mm +26mm +30mm +36mm +42mm +48mm +54mm
6.5″ -12mm -6mm 0 +6mm +12mm +18mm +26mm +30mm +36mm +42mm +48mm
7.0″ -18mm -12mm -6mm 0 +6mm +12mm +18mm +26mm +30mm +36mm +42mm
7.5″ -24mm -18mm -12mm -6mm 0 +6mm +12mm +18mm +26mm +30mm +36mm
8.0″ -30mm -24mm -18mm -12mm -6mm 0 +6mm +12mm +18mm +26mm +30mm
8.5″ -36mm -30mm -24mm -18mm -12mm -6mm 0 +6mm +12mm +18mm +26mm
9.0″ -42mm -36mm -30mm -24mm -18mm -12mm -6mm 0 +6mm +12mm +18mm
9.5″ -48mm -42mm -36mm -30mm -24mm -18mm -12mm -6mm 0 +6mm +12mm
10.0″ -54mm -48mm -42mm -36mm -30mm -24mm -18mm -12mm -6mm 0 +6mm
10.5″ -66mm -60mm -54mm -48mm -42mm -36mm -24mm -18mm -12mm -6mm 0
11.0″ -72mm -66mm -60mm -54mm -48mm -42mm -36mm -24mm -18mm -12mm -6mm
12.0″ -78mm -72mm -66mm -60mm -54mm -48mm -42mm -36mm -30mm -24mm -18mm


How to Measure Wheel Backspacing

When determining wheel backspacing, measurements are taken in inches. It represents the distance from the hub mounting surface to the rear edge of the wheel. 

Here’s how to do it: 

Position the Wheel: Position the wheel by laying it face down on a flat surface.

Align the Straightedge: Position the straightedge across the back of the wheel, ensuring it touches the mounting surface.

Measure the Distance: Use the ruler to measure the distance between the mounting surface and the straightedge. This measurement is your wheel backspacing.

How to Check Backspacing on Wheels

First, gently place your wheel face down on a level surface. Then, position a straight, flat object, such as a wooden plank or yardstick, across the diameter of the wheel, making sure it spans both ends adequately. Finally, a ruler will be used to measure the distance from the bottom of the selected object to the mounting surface in inches. 

Where to Find the Wheel Offset Number on a Wheel?

You can locate the offset measurements on the back of your wheel, usually following the letters “ET.”

Why Do Wheel Offset and Backspacing Matter?

Understanding wheel backspacing and offset is essential for the appearance, performance, and handling of your vehicle. While driving, it’s crucial to prevent any rubbing between wheels, tires, and essential components. The wrong offset and backspacing measurements could adversely affect your steering, suspension systems, fenders, frames, and brakes.

Proper backspacing and offset are important to prevent unnecessary wear or damage to your vehicle and tires. By selecting the correct fit, you ensure adequate space for the essential components of your vehicle to function without interference from the wheels.


At Quality Tire Custom Auto Shoppe, we understand the importance of wheel offset and backspacing in enhancing your vehicle’s appearance and performance. Our commitment to providing high-quality aftermarket auto parts ensures that you can find the perfect fit for your car, truck, or SUV. Upgrade your wheels with confidence and precision with Quality Tire Custom Auto Shoppe!  

Contact us at (703) 491-9005 to explore our wide selection of custom wheels and expert services.