#TechTip: Can You Calculate Offset?
Offset can be a bit of a confusing number, especially if you’re new to the world of wheels, so here’s a breakdown:
Offset is simply the distance from the center of a wheel to the mounting surface of that wheel.
Offset can be a bit of a confusing number, especially if you’re new to the world of wheels, so here’s a breakdown:
Offset is simply the distance from the center of a wheel to the mounting surface of that wheel.
Below, you’ll see a zero offset wheel, meaning that the mounting surface is exactly at the centerline of that wheel.
Offsets can be positive or negative.
Generally speaking, the lower the offset is, the further out it will sit.
Negative Offset
The higher the offset, the further in the wheel will sit.
Understanding the wheel width along with the offset will allow you to measure how far the lips of the wheel will sit in or out in the wheel well, giving you a better idea of the clearance you have to work with.
How To Calculate Your Offset
In order to calculate your offset, you also need to know what backspacing is. Backspacing is simply the distance from the mounting surface of the wheel to the back of the wheel.
To calculate the value of your offset:
1. Measure the width of the wheel (in mm)
2. Divide the width by 2
3. Subtract the back spacing (in mm)
Have a subject you’d like to learn more about? Comment it below!
Comments
I’m currently thinking about some new wheels! Thank you.
We’re all thinking about new wheels.
Really helpful and easy to understand! Thanks matey
No problem matey!
I can understand negative offset, but whats the point of positive offset?
possibly dumb question
Just depends on your application! For example, if you wanted to increase your wheel width by a few inches but you liked the outside of the wheel where it was, you could use a greater offset to put that width further in.
When do the two become useful?
Well the offset determines the centre of the wheel in relation to the mounting surface (as mentioned above). There is actually a reason why it’s important: the steering geometry is setup using this offset. If you were to change the offset on the front wheels of your car then it could potentially have an affect on the handling, nothing to worry about for a daily driver perhaps but for a track/race car it could be a problem.It’s all to do with Ackerman steering if you want to read up more I would suggest this:http://www.motor.org.uk/documentlibrary/Sep%2009/TT%20_%20Sept%2009.pdf
Hope it helps 😊
when you wanna purchase mad wheels but don’t know of they fit inside your wheelarches. Say you like your new rims to come outward 10mm more you can fit the same width wheel with a 10mm lower offset. I am going to fit ET40 9Js on a car that originally has ET50 7Js, you gotta do some good measuring and calculating to know such a huge difference fits. Or you might be ordering a set of useless rims. trying out rims is also a good option of you’re buying new rims, I tried fitting a ET30 8,5J and it worked, so when you do the math my news rims are gauranteed to fit too
Result:Miata,have i done something wrong?
Nope. It sounds like you did something right!
Camber I would like to know how you calculate it.
Hold a protractor against your wheels.
Yea I calculated it with hopes and luck
That usually works too :)
Does wheel width matter if I want to make my tires flush to the fender?
Wheel width IS something you need to take into consideration!
Always good to learn something new
Maybe something about bore x stroke
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