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Custom Wheel Offset: Measuring Guide

Custom Wheel Offset: Measuring Guide

It’s time to fit your whip with a new set of rims, and you’ve got something specific in mind. You want to go for a new look, something that stands out.  

Maybe you want wheels that seem to stick out from the well, almost like deep dish pizza pans. Or perhaps you’re more interested in rims that fit so snuggly into your car's body that they might as well be part of the frame. 

At Rent A Wheel, we have all of these options and more. Our team of professional tire experts is ready to help you figure out which custom offset wheels will best fit your vehicle and look exactly how you dreamed. 

Still, maybe you’re the type of driver who wants to know all of the data before going shopping. We tip our caps to you, shopper. 

You’re doing your homework. Excellent! Knowing what to look for on your vehicle, on your current rims, and on your soon-to-be new set of offset custom wheels is hugely important, especially if you’re going for one of these flashy looks. Getting the wrong set of rims could seriously damage your suspension and brake systems. 

Don’t be scared! You just need to know what to measure, what your car can handle, and how to tell our experts exactly what you want. 

The Two Main Types of Measurements

Two different measurements play a big role in how your installed wheels will look: the offset and the backspace.

You’ll also want to know the depth of your wheel well, but we’ll address that later. 


We know this article says it’s about offset measuring, but you’ll want to find the backspace first. It’ll make things easier. 

Measuring the backspace is very simple. Take your rims off of your car, and take your tires off of their rims.

The backspace is the measurement from the backside of the wheel's connection point, where it locks up with your car to the outer edge of the rim’s back edge. 

This is doneby laying the wheel on the ground with its face side down. Next, take something long and straight like a metal bar or yardstick and lay it across the wheel as close to the center as you can get it. 

Take a measuring tape and measure from the center into the wheel until you hit the connection surface. This is the space between the connection surface and the back of the wheel—which means the name “backspace” makes a lot of sense, right? 


a Lamborghini showing offset wheels


The offset is generally the most talked about measurement when shopping for any new rims. 

An offset is the measurement of the connection surface relative to the centerline of the rim. 

Imagine your wheel is standing upright. To find the centerline, slice down the rim’s center to make two perfectly even discs, like two cookies ready to become an ice cream sandwich. (We know that’s a weird reference, but we’re hungry and it’s dessert time.)

Anyway, there’s a relatively simple way to find your offset now that we know the backspace measurement. All you have to do is measure the width of your rim from front flange to back flange, then slice that in half and subtract the backspace. 

Here’s an example: 

You measure the backspace of your wheel, and it’s six inches even. 

Next, you measure the total width of your wheel. It’s 14 inches flat. Cut that in half, and you have seven inches. 

Seven minus six is one. So, you have an offset of one inch. But wait, there’s more! 


a black car showing wheel offset

Positive Vs. Negative Offset 

There are two different kinds of offset: positive and negative. 

A positive offset is when the connection surface is closer to the front face of the wheel. This pulls the connection surface forward and gives the wheels that tight, tucked-in look. For example, these Cavallo CLV-15s have that super clean, flush look. 

A negative offset is when the connection surface is closer to the back of the wheel, away from the street-facing side. The further the distance from the connection surface and the rim’s inner face, the more depth the rim appears to have. If you’re having a hard time picturing this, take a look at these wicked Moto Metal MO985 Breakouts

Pop quiz: Was our one inch offset from the example positive or negative? Don’t worry; it’s harder to visualize just from numbers and much easier to tell in person. 

An easy way to determine positive or negative offset is to ask whether your backspace measurement is less than half of your wheel’s width measurement. If this is the case, the offset is negative because the surface point is behind the centerline. 

One more thing to remember: offset itself is always measured in millimeters, which means you’ll have to convert your measurements. In our imaginary case, this car has 25.6 millimeters of negative offset. 


an Audi showing tire clearance


See, we told you we would come back to it! 

Clearance is the space within your wheel well for the wheel itself, the suspension system, and everything else. 

If you have a large amount of positive offset and your wheels are jamming into the interior wheel well of your car's body, you’re going to have some major suspension issues. Not only that, but you might squeeze your brake calipers if you start speeding and your rims expand too much. That’s no joke. 

If you have a big shift in negative offset and your wheels are sticking outside your body, you might hear some loud rubbing noises when you take sharp turns. That’s your tires giving an unwanted polish to the outside of your car’s wheel well. 

It’s difficult to measure clearance and foresee how large amounts of offset will impact your car, which brings us to our final point.

Get Some Professional Guidance

Buying wheels with a large difference in offset can be a hazardous experiment by yourself. 

Depending on the look you want, you might need to have work done on your car’s body to flare out your wheel wells. 

You also might need to look into a brake system that doesn’t have much protrusion so that your wheels can be flush. 

Whatever the intended outcome, it’s always a safe bet to work with professionals. At Rent A Wheel, we’re always happy to help.

Our team of professionals can make detailed suggestions depending on your goals. Our online visualizer can help you look at what your vehicle will look like fitted with options that we know will fit.

The Takeaway

You have the tools you need to walk into a conversation about custom wheel offset confidently.

You know how to measure your current offset and backspace. You know the difference between negative and positive offset and how they change the way your wheels and car can look. 

At Rent A Wheel, we want our customers to feel comfortable and confident with their purchases. Your car is a big deal, and that’s how we treat every vehicle that comes our way.

When you’re looking to purchase a new set of custom offset wheels and tires, take advantage of our killer visualizer, our crack team of tire experts, and our flexible payment plan options. Some wheels can seem like a hefty investment. At Rent A Wheel, we make sure you can get the wheels you want without breaking the bank. 



Wheel Measure Guide | Jegs

Inches to mm converter | Rapid Tables

How to Measure Wheel Offset | EFX Tires