Wheel offset (ET or IS) is the measure of the span between the bolting face of the hub and the centerline of a wheel. It is usually measured in millimeters and stamped in the back of most rims. If the wheel's mounting surface is flushed with the centerline you have a Zero offset. If the hub mounting surface is closer to the face of the rim it's Positive, and if it is closer to the back of the wheel, it's Negative.

As you can see, the exact middle of the width of the rim (between the tire bead seat) is the Center Line.

The distance between this centerline and the bolting face of the hub is your wheel offset.

As a result, it is divided into 3 main denominations according to the relation of the distance of the hub mounting surface and the wheel's centerline.

ZERO OFFSET – is when the hub mounting face is flush or aligned with the centerline. Wheels with zero offset we usually designed for rear wheel drive vehicles.

POSITIVE OFFSET – that is when the hub mounting surface is more towards the face of the wheel. Since the hub sits towards the front of the wheel, the rim moves towards your vehicle and they have little or no lip.

Most factory OEM wheels fall in this category.

We have installed an OEM Wheel offset calculator and database on our site to help you with your research. It's a FREE tool that contains a wheel offset chart with wheels offset from all brands and models in various markets. For your convenience, we have included a link at the end of this article.

NEGATIVE OFFSET – in contrast, if the hub mounting surface is closer to the back of the wheel, before the centerline, you have a negative offset. In this case, the wheel sits more towards the outside of your vehicle, that means that wheel and tire are not flushed with your vehicle body, giving you a “wide” look.

Negative offset wheels usually include wide custom rims with deep dish and aftermarket forged wheels.

Positive offset vs. Negative offset: The Saga Continues

Now, in the world of offsets, positive is not always good, and negative isn't necessarily bad. It's more about how you want your car to strut its stuff on the road.

Factory wheels are designed with positive wheel offset, keeping the wheel width within safe and traditional parameters:

• Wheels for Rear Wheel Drive vehicles (RWD) have positive offsets ranging from 40 to 61 mm
• Wheels for Front Wheel Drive cars (FWD) have wheel offsets ranging from 0 to 28 mm
• While wheels for All Wheel Drive vehicles (AWD) have mid-offsets from 29 to 35 mm

In contrast, some offset negative Aftermarket wheels will look great on your car or truck, provided you don't choose wheels with too much negative offset measurements.

How to measure a rim offset

How wheel offset refers to a measurement is a question easy to answer.

First, keep in mind that determining the centerline is the first step in calculating your offset. In other words, if your rim is 9-inch-wide, divide the width by 2 and you will get a 4.5-inch centerline.

Now, get your metric system ruler and measure the distance between the centerline and the face of the hub. Finally, the result is your offset.

Now, do you have to learn all this technical stuff? Off course, not!

Thank god there is an easy way to find your offset without all this measuring!

How do I find my rims offset?

Luckily 99% of the wheels in today's market, being OEM wheels or custom aftermarket rims, have the offset stamped by the factory on the wheel itself.

Look at the markings stamped in the reverse of the wheel, often behind one of the spokes. There you will see several markings like brand, manufacturing, part number and the size of the wheel.

The rims offset is most times next to the wheel size stamp, and often following the nomenclature ET (for ‘Einpresstiefe', the German word for offset or “insertion depth”).

So, if the stamp has an ET47 you have a Positive Offset of 47 mm. In contrast, if it says ET-40, you have a 40 mm Negative Offset

How to measure a rim offset

How wheel offset refers to a measurement is a question easy to answer.

First, keep in mind that determining the centerline is the first step in calculating your offset. In other words, if your rim is 9-inch-wide, divide the width by 2 and you will get a 4.5-inch centerline.

Now, get your metric system ruler and measure the distance between the centerline and the face of the hub. Finally, the result is your offset.

Now, do you have to learn all this technical stuff? Off course, not!

Thank god there is an easy way to find your offset without all this measuring!

How do I find my rims offset?

Luckily 99% of the wheels in today's market, being OEM wheels or custom aftermarket rims, have the offset stamped by the factory on the wheel itself.

Look at the markings stamped in the reverse of the wheel, often behind one of the spokes. There you will see several markings like brand, manufacturing, part number and the size of the wheel.

The rims offset is most times next to the wheel size stamp, and often following the nomenclature ET (for ‘Einpresstiefe', the German word for offset or “insertion depth”).

So, if the stamp has an ET47 you have a Positive Offset of 47 mm. In contrast, if it says ET-40, you have a 40 mm Negative Offset

Want to see the offset your factory wheels came with? Whant to know what is the proper wheel offset or the wrong offset for your vehicle?

Now it's easy. We've installed a FREE wheel and tire calculator and database at www.wheelsmartrims.com.

You are invited to come in and research the information by your vehicle's Year, Make and Model, by rim size or by tire size.