When shopping for aftermarket wheels, the most common measurements that a lot of people get confused by are offset and back spacing.
Our website is dedicated to helping you figure out the right wheel offset and back spacing for your vehicle and understand what they actually are.
Offset is the distance from the centerline of the wheel to the back pad, a mounting surface where the wheels actually get put onto your car.
Offset of the wheel is the relationship of the face of the hub to the centerline of the wheel.
How do we find the true width of the wheel?
It is important to measure the width from the bead to the bead. That is the true width of the wheel. If you have a spare set of wheel you are not going to measure from the outside to the outside.
Zero offset means the face of the hub on the inside of the wheel is dead center in the wheel.
If the face of the hub moves towards the front of the wheel, that stands for the positive offset.
If the face of the hub moves towards the rear of the wheel or the inside, that is negative offset.
For example, 40 mm of positive offset means the wheel is 40 millimeters towards the front of the wheel.
Back spacing is the amount of wheel that sticks out past the face of the hub.
How to find the offset of the wheel? Let’s try to figure out on the following example.
- Put the wheel of the flat surface
- Measure the width of the wheel (distance between the surface it touches to the upper point)
- Find the centerline by dividing the width by half (for example, if the width is 9 inches, center of the wheel is – 4.5 inches)
- Measure the backspacing (distance from the face of the hub to the top of the wheel), let’s say 6 inches.
- Wheel offset would be the difference between backspacing and center of the wheel (6 inches minus 4.5 inches = 1.5 inches or 40 mm)
- In this case the hub would be towards the center of the wheel, so it is positive offset 1.5 inches.
Another thing you have to consider is the brake clearance. It is especially important on vehicles with Brembos or big break kits.
What is the practical use of the wheel offset and backspacing? Why do you even need to know these numbers?
With a positive offset the wheel gets a flush, flatter look.
With negative offset you get a dish or bold look by moving the hub to the back.
Offset also has an effect on how much the wheel sticks out past your fender or goes inside the fender.
The more positive offset you have the further the wheel is going to be in from the fender.
The more negative offset you have the further the wheel is going to stick out.
Zero offset is your center line.
Back spacing is super important if you are planning to get wider wheels. Improper backspacing may cause clearance issues. So when shopping for aftermarket wheels make sure you know how much backspacing you can run.
We have an extensive database of stock and aftermarket wheel offset measurements for all the vehicles. Choose your make, model and year to run the wheel offset chart for your car.