The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types (measured in millimeters).*
"The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel."
The hub mounting surface is even with the centerline of the wheel.
The hub mounting surface is located in the front half of the wheel closer to the wheel face. This tucks the entire wheel in toward the brakes and vehicle suspension. Positive offset wheels are generally found on front-wheel drive cars and newer rear-wheel drive cars.
The hub mounting surface is located in the back half of the wheel closer to the back lip flange. This moves the wheel out away from the vehicle brakes and suspension. "Deep dish" wheels and wheels for lifted trucks are typically a negative offset.
If the offset of the wheel is not correct for the car, the handling can be adversely affected. Often, when changing the width of the wheel, the offset will also need to change to maintain proper clearances inside the wheel well. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly. We test fit thousands of different vehicle and wheel size combinations to confirm which ones work correctly. Our extensive database allows our sales staff to offer you the perfect fit for your vehicle.
*Backspacing, similar to offset, is the distance from the hub mounting surface to the inside lip of the wheel (measured in inches).