If you are on the lookout for new rims or are planning to upgrade your car.
You must have heard about rim offsets, backspacing, scrub radius, or related terminologies.
So, what exactly are they and how can rim offsets affect the performance of your car?
This guide will take a detailed look at what rim offsets mean and how they affect your car.
A Brief Overview of Wheel Offsets
In the simplest terms, wheel offset or rim offset is the distance between the centerline of your wheel and the mounting hub of your car.
The right amount of offset is important to maintain because it has a direct effect on your driving performance and experience.
There is no right rim offset because it depends on several factors including your car type, the tires you have, and your driving requirement.
Generally, the offset is represented by a number where 0 means zero offsets and a positive or negative number indicates the corresponding offsets in millimeters.
Let’s take a look at exactly what positive, negative, and zero offsets mean.
Positive Offset
A positive offset means that the mounting surface of the car is further away from the chassis or body and more towards the street.
It has a lot of uses and is generally the default setting in most cars. Car manufacturers commonly roll out cars with an offset in the range of +12 to +20.
This means that the wheels protrude towards the street by 12 to 20mm.
Negative Offset
Similarly, a negative offset means that the wheel mounting surface is behind the centerline.
You must have seen unusual rims that may look like a deep dish. That’s a common characteristic of the negative offset rim because the mounts are towards the suspension components.
Zero Offset
Finally, zero offsets are the original setting where the mounting surface sits exactly at the centerline of the wheel.
Why it isn’t the default setting in passenger cars is because of the changing requirements of the car market.
The offset directly affects the handling, feel, and ride quality.
Keeping at exactly zero doesn’t work as well as other options when you consider the requirements of the consumer segment.
Wheel Offsets vs Backspacing: What’s the Difference?
Technically backspacing and rim offsets are the same things.
The only difference is the reference you use.
Wheel offsets use the centerline of the wheel as the reference where the positive offset is towards the road and the negative offset is towards your car’s suspension.
Backspacing is different.
The reference, in that case, is the inner end of the wheel.
This means that backspacing will be zero at the negative end (towards suspension) and maximum at the positive end (towards the road) of the wheel.
If you are using this system, you’ll have to deal with higher and lower backspacing.
Higher backspace is just like a positive offset where you’ll have lower wheel clearance on the wheel. Similarly, lower backspace means the negative offset with more clearance.
So, to sum up, backspacing and rim offsets are practically the same thing.
They are just two ways of representing the same thing.
The Importance of Rim Offsets and How They Affect Your Car
Both negative and positive wheel offsets come with their set of pros and cons.
Generally, the most common reasons why people tweak their offset settings are to improve the handling experience, enhance ride quality, fit after-market wheels, or go for a specific look.
In all cases, the process is reversible but is extremely important because even a small difference can have a huge impact on your driving experience.
Generally, it’s very common for people to change their offset settings when they opt for new wheels.
The final requirement can either be form or function, but you should know both the advantages and disadvantages of your preferred measurement before moving forward.
The next section will take a look at the pros and cons of both positive offsets and their negative counterparts.
Positive vs Negative Offsets: The Pros and Cons
If we ignore zero-wheel offset as it acts only as a reference for the passenger section today, then you’ll have two options.
Positive or negative wheel offset. Both settings come with their set of pros and cons related to road feel, handling, and the overall looks.
As a user, you need to find the right tradeoff between the three settings.
Here are a few of the advantages and disadvantages of both positive and negative rim offsets in your car.
Advantages of Positive Offset
A positive offset in wheels is a more common and preferred approach because of its numerous advantages.
The functionality is top-notch, but your car won’t look any different.
If you are someone who must have a car that stands out on the road, then this is not the right choice for you.
For literally everyone else, the positive offset is the way to go!
Here are a few major advantages of positive wheel offsets.
1. Suitable for Wide Tires
If you are using wider tires on your AWD or a 4×4, then positive offset rims are your best bet.
They’ll leave ample clearance in the hub to allow excellent maneuverability without any issues down the line.
Positive offset simply gives you the best performance if you are using wide tires.
2. A Neat and Regular Look
As discussed, positive offset tires operate on a different scale where they let you get decent performance and deliver a regular look.
This means that the car will look exceptionally ordinary or as intended by the manufacturer.
Some people find the charm in that look and this is the best for you if you are one of those.
3. No Rubbing Sounds
Finally, because of the ample clearance that positive offset delivers, you get the guarantee that there will be no annoying rubbing sounds and unnecessary wear on your tire from the fender.
Some drivers really hate that and a positive offset can put them at peace.
Disadvantages of Positive Offset
As for the disadvantages apart from the aesthetics, the only thing worth mentioning is the clearance issues with the brakes and suspension parts.
This is only for very compact cars like hatchbacks where you have limited space in the hub.
For larger SUVs, this is not an issue as there is ample clearance for brake and suspension parts.
However, if you are dealing with clearance issues because of positive offset, then be extra careful because they can lead to tire failure which is both dangerous and costly.
Advantages of Negative Offset
Negative offsets have a series of advantages concerned with both form and function.
This wheel offset setting gives you a better wheel fitment and stance. Moreover, you also obtain a wider track and more stability during the drive.
Let’s take a detailed look at these advantages.
1. Enhanced Parking Stance
One of the most noticeable changes in your car will be in its look.
Negative offset wheels give off a certain vibe that will allow your car to stand out from the rest because of the internal protruding rim and better-fitting tires.
It is, however, important to note that looks are something very subjective.
What looks awesome and cool to someone might not look the same to someone else. So, you should be very careful regarding your choice.
2 . Greater Stability
The track, the distance between the centerline of your passenger and driver sides, is the primary determinant of the overall stability of your car.
A negative offset will widen the track and give you more control at the expense of road feel or feedback.
3. Better Track Performance
Finally, a negative offset will also give you enhanced performance on the track or a paved surface because of better stability and cornering performance.
However, your off-road performance will deteriorate so don’t go too overboard with the decision.
Disadvantages of Negative Offset
The aforementioned advantages may look great, but there are serious drawbacks as well.
The negative offset can prematurely damage your suspension, cause tire damage, and offer low road feedback.
Let’s take a detailed look at each issue.
1. Damage to Suspension Components
The wide track that having a negative offset offers can put a lot of strain on your suspension components, especially the bearings.
So, you should be prepared to break the bank on stronger after-market components or frequent replacements to maintain your car in prime condition.
2. Tire Wear
Another common problem due to having a negative offset is your tire rubbing on the fender.
This not only damages the body but also causes unnecessary wear on the tire as well.
You’ll also feel annoyed while driving because a rubbing tire will create an obnoxious sound that no driver likes.
3. Low Road Feedback
The better performance that you get from a negative offset comes at a catch. You get very little road feedback that can affect your driving experience.
DIY Guide to Measure the Wheel Offset of Your Car
While most rims will come with all the information you need handy, knowing how to calculate the offset can be a handy skill.
If you dabble in used parts, then it becomes even more important because, unlike new parts, the market for second-hand car items is disorganized and quite difficult to navigate.
Calculating the rim offset is not that hard as well and you don’t need to invest in a lot of tools.
All you’ll need is a couple of rulers, straight edges, and the calculator on your phone.
Here’s how you can start calculating the rim offset of your car:
Determine the Centerline
Lay your wheel on a flat surface and measure the overall depth with a ruler.
Once you have determined the full width, simply divide it by two to get the distance between the wheel-end and the centerline.
Calculate the Backspacing
Use the same process as before, but this time use the mounting points as a reference and find the distance from the end of the wheel. You’ve obtained the backspacing now.
Calculate the Offset
The next part is simple. Use the following formula to calculate the total offset.
Offset = Backspace – Centerline
In this case, a negative value means negative offset and a positive value means the opposite. Simple and sweet!
Wheel Offsets and Scrub Radius: How Are They Related?
Another important thing that you must consider while changing the rim offset from default is the scrub radius.
The scrub radius is the intersection of the steering axis and the centerline of your wheel.
It determines how much load falls on your car’s suspension and plays a significant role in keeping the ride comfortable for you.
Just like the offset, the scrub radius has three orientations; zero, positive, and negative.
A positive scrub radius significantly increases the effort you must put to steer the wheel.
It obviously becomes even more difficult if you are driving an older model or vintage car with a hydraulic steering system rather than an electric power one.
You’ll need more torque to move the wheel, which will in turn make driving difficult for you.
Zero scrub radius completely eliminates the difficulty in steering and makes it very easy.
However, there is a catch.
This orientation is extremely unstable and doesn’t deliver any road feel at all. Moreover, you won’t feel any steering feedback on bumps and potholes.
Negative scrub radius is the most common orientation, but also comes with some issues.
It comes with moderate torque requirements and better kickback. However, the road feel will still be quite low.
All three orientations may seem full of disadvantages to you because there is no such thing as the best scrub radius.
The correct choice depends on your driving demands and requirements.
Final Thoughts on Wheel Offset and Backspacing
If you are not an expert and just want a car for your day-to-day use, then anyone will tell you that tampering with the offset is not worth the trouble.
Even the smallest deviation can have a significant effect and reduce the overall quality of your drive.
However, if you know what you are doing, dealing with wheel offsets can help you get the best out of your car.
And the best part is that the car will look awesome and stand out on the road.
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