What is Wheel Offset, And How Do You Choose Offset for New Rims?

Tire Agent requires you to confirm your wheel’s offset before purchasing a new set of rims. What does wheel offset mean? How do you find your wheel offset? Does the new aftermarket wheel offset have to be the same as the original equipment? We answer these questions and more.

Wheel offset measurement ensures your wheels and tires fit correctly. Let's look at what wheel offset actually means and how to choose the right size.

Defining Wheel Offset and Why It Matters

Wheel offset is defined as the distance between the wheel's mounting surface and the centerline, measured in millimeters.

When you replace your wheels or rims, you want to carefully measure to ensure your tires fit properly in the wheel well without rubbing against the fender, frame, suspension, or other vehicle components. That's where offset and backspacing come into play.

This illustration shows what wheel offset looks like:

Offset and backspacing are two crucial measurements that indicate a wheel's proper location.

Backspacing is the distance between the wheel's mounting surface and the innermost lip, measured in inches.

If you opt to install aftermarket wheels, you'll need to know these measurements because they help identify which wheels are compatible with your vehicle.

How to find wheel offset

If you're a hands-on type of person, you can find the wheel offset of your current wheels relatively easily. It's usually stamped on the back of OEM or factory wheels, on the hub area or a spoke, next to the letters ET.

How to measure wheel offset

Wheel offset can be found on your own, but you’ll need to be able to take your wheel off first so that you can lay it flat. You’ll also need a straightedge. If you have a full-size spare, like many off-roading Jeeps do, this is a bit easier. Remember that most wheels have the offset stamped on the back of the wheel. 

The offset is the difference between the center of the wheel and the mounting point, or where the wheel is mounted to your car. Offset is measured in millimeters, so you’ll need a ruler that has centimeter markings and then convert them to millimeters once you’ve made your calculations. 

1. Lay a straightedge across the face of the wheel, flange to flange. This gives you an accurate reference for the outer edge of the wheel. 
2. Measure the backspacing, which is the distance between the wheel’s mounting surface and the innermost lip.
3. Measure the overall width, flange to flange, not the stamped width. The center of the wheel will be one half of that overall width. 
4. Subtract the centerline measurement from the backspacing. Convert it to millimeters. This is your offset. 

Remember that it’s OK if this is a negative number, it just means you have a negative offset!

Types of Wheel Offset

The offset of a wheel is determined by measuring the distance between the wheel's centerline and the mounting surface. The standard unit for describing offset is millimeters, which can be positive, zero, or negative.

Rim offset meaning:

• Zero offset: The wheel's mounting surface must line up with the centerline to be considered zero offset.
• Negative offset: A mounting surface closer to the back of the wheel is referred to as a negative offset.
• Positive offset: A mounting surface that extends over the centerline and closer to the face of the wheel is referred to as positive offset. Many factory rims have this offset type.

Positive vs negative wheel offsets

Each vehicle has its own offset. The difference between positive offset and negative offset is: A positive offset is common in modern front-wheel-drive automobiles, while a negative offset is common in older or customized vehicles. The precise offset data is imprinted on the mounting surface, or a spoke on most wheels.

What about backspacing? Backspacing is the space between the mounting point of the wheel and the outside of the wheel that faces towards your car. This is an older method of determining the depth of the mounting pad within the wheel. Correct backspacing gives the suspension, braking, and steering systems ample room to operate without interference from the wheel.

Backspacing is increased when the offset is positive, while it is reduced when the offset is negative. The suitable backspacing of each wheel, like offset, is determined by the vehicle's size and design.

Common offset ranges by vehicle type

Most sedans and passenger vehicles have positive offsets ranging from +30mm to +50mm. Positive offset tucks the wheel further under the vehicle, which is typical of front-wheel-drive packaging. 

Negative offsets are usually seen on lifted trucks that have larger tires and wider stances. The negative offset helps the larger tires fit in the wheel well and achieves that unique larger truck style. 

FAQs About Wheel Offset

What happens if you get the wrong offset?

If you get the wrong offset for your car, you risk damaging your tire or the suspension of your vehicle. A wheel’s offset changes the position of the tire, so an unintended offset for a car may cause the wheel or rubber to rub against the suspension arms, the brakes, or the inside of your wheel well. This will damage your tires and put a lot of stress on your suspension.

Staying as close as possible to the OEM offset is the safest route. 

Can offsets vary by axle? 

Offsets can vary by front vs rear axle if you’re trying to achieve a certain staggered look or stance, but for most passenger vehicles this isn’t something you want. Different front and rear offsets are uncommon on most passenger vehicles, though staggered setups are standard on some rear-wheel-drive performance cars. Only have different offsets if you have experience with creating car builds. 

Will the wrong offset hurt my suspension? 

Yes. Too much positive offset rubs inboard components; too much negative offset rubs the fender. 

Where do I find my wheel offset, if I don’t have OEM wheels?

Most wheels have the offset stamped on their back, usually on the inner rim or one of the spokes. It will be “ET” and then a number that’s either 0, positive, or negative. ET47 would be a positive offset of 47mm.

Can I use wheels with a different offset for a stance/fitment look?

Yes, if you purchase a set of new aftermarket wheels, you can get new offsets to achieve a new look. A 0 offset will make your wheel and tire look flush with the rest of your vehicle. Negative offsets push the wheel out, making your vehicle look like it has a wider stance. 

Pushing the wheel outward puts added load on wheel bearings and suspension components and can cause fender rubbing at full lock or under compression. You also risk wearing down your tires faster or even damaging them if you don’t have the right tire size, wheel width, and fender clearance. You can check the placard sticker on the driver’s side door or your manual to see the recommended offset for your car. 

Do your research before swapping to a negative offset and make sure you have a professional installing your wheels. You could cost yourself hundreds to thousands of dollars if you install the incorrect offset. 

ID 20882564 | Car Wheel | Sawitri Khromkrathok | Dreamstime.com

Wheel offset illustration: By Matterhorny - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=116077723 no changes were made