A car’s wheels are among the first modifications for anyone interested in customizing their car. The looks and fitment of wheels directly affect how any car looks, and fitting great-looking wheels to your car can completely change its looks. The problem is that the design isn’t the only thing that changes the look of a vehicle.
A couple of measurements have an effect mainly on how wheels look when fitted to a specific car, but also how it will handle. One of these measurements is the wheel offset. In this article, we’ll cover everything there is to know about wheel offset.
What is Wheel Offset?
In order to understand anything in this article, we’ll need to start with the basics. Wheel offset, or ET as many call it, is the distance between the mounting hub on the wheel and the center of the wheel. Each vehicle model has a specific factory offset, and wheels, whether they’re OEM or aftermarket, have specific offset measures that you need to take into consideration if you plan on replacing your factory wheels with another set.
Even though wheel offset is one of a few measurements on the wheels, it plays a significant role in how your car will look and handle.
Types Of Wheel Offset
If you think about wheel offset, you’ll quickly realize that the wheel offset can be neutral, more towards the inside of the wheel, or more towards the outside of the wheel. This is either a positive or negative wheel offset.
Zero wheel offset is when the center of the wheel aligns exactly with the mounting surface that goes onto the hub. Positive wheel offset means that the wheel hub surface is pushed towards the face of the wheel, while negative wheel offset means that the mounting surface is located deeper inside the wheel barrel, further away from the face of the wheel.
Wheel Offset Effects On Fitment and Performance
Most wheels that can be fitted on regular daily driven cars have wheel offsets ranging from -35 to +35. Specific car models require specific wheel offsets for the best look-to-performance ratio, however, it’s sometimes difficult to find exactly the type of wheel you want that will have all the correct adjustments to fit your car exactly how you imagined.
Due to these differences, it’s important to know what each wheel measure means, and how it will affect your car, whether it’s on performance or visuals. Wheel offset affects both of these features.
When it comes to fitment, the more positive the wheel offset is, the more tucked the wheel will be under the fenders. On the other hand, the more negative the offset is, the wheel will be pushed further outside.
When the wheel offset is positive, there’s a possibility you won’t be able to even fit the new wheels and tires. This is because the wheel and tire will be tucked under the car too much, hitting some of the suspension components. Negative offset, on the other hand, can lead to damaging the wheels and tires because they’ll hit the fender every time the car hits a bump on the road. This is why it’s important to carefully pick the wheels you’ll mount to your car.
Regarding performance, negative wheel offset will help you increase your car’s handling capabilities. This is because the car will have a wider stance, and a lower center of gravity because of it. Adding spacers to the wheel hubs can also help in achieving a wider stance, or fitting wheels with a more positive offset than required for your car.
Can Wheel Offset Be Measured?
Most wheels, whether they’re OEM or aftermarket, are engraved with exact measurements. If you know which wheel model you have, you can also find all the measurements on the internet, however, you can also measure the wheels yourself in case the measurements on the wheels are damaged, or you can’t find the information about a specific model of wheels online.
There are five main measurements you need to know. These include the bolt pattern, center bore diameter, wheel diameter, wheel width, and wheel offset. All of these measurements have a certain effect on whether a wheel can be fitted to a car.
Contrary to popular opinion, the wheel diameter isn’t measured from edge to edge. The real diameter is measured without the protective lip where the tire sits. The wheel diameter is measured in inches. You can do this with a simple tape measure.
The same applies to the wheel width. Measure the width of the barrel without the protective lips on the side. This is also measured in inches.
The bolt pattern is simple. You need to count the number of bolts that are required to tighten the wheel to the hub, and measure the diameter of the imaginary circle going through the center of those bolts.
Now, for the wheel offset, you’ll need a ruler, or a straight piece of wood you can put on the wheel while it’s face-down. The next thing you’ll need to do is measure the distance between the mounting hub surface to the end of the wheel, and add or subtract half of the wheel’s width. This will equal the wheel’s offset or ET.
The easiest way to find the offset of any wheel is to search for it online. This will require you to know who the manufacturer is, the bolt pattern, and the model name.
How To Fit Wheels That Don’t Have A Correct Offset For Your Car?
In certain situations, it will be impossible to find a set of wheels you really like, with the correct diameter, bolt pattern, and offset. Thankfully, the offset can be adjusted with help of spacers. Many consider them an unsafe modification, but if they’re made from high-quality materials, and fitted properly, you won’t have a thing to worry about. If you’re going to mount spacers yourself, make sure you get the right bolts and double-check everything you do.
Spacers will push the wheels out a certain length, however, bigger doesn’t mean better here. The safest option is to choose a spacer up to 25 millimeters wide.
If you’re not sure about spacers, there’s one more option you could try, and that’s adjusting camber. Sometimes, only a little space is needed for the wheels to fit under the fender, and offset will help you with that. There’s a downside to offset, and that’s increased tire and suspension component wear.