Press-in (ET) / Offset
When you need new or used rims for your car, there are a few different factors that you need to keep an eye on. One of them is Offset, which you can read more about on this page, as well as how it is calculated. In common parlance, you will often hear people call Offset "ET".
The ET measurement is one of the important factors when it comes to rims for your car. The ET measurement, together with the width, determines how far in or out the rim sits on your car.
A rule of thumb is that you can go 10 +- compared to the measurements that your car was born with from the factory.
The ET measurement is measured from the center of the rim, the surface that meets your car's hub, out to the edge of the front of the rim. If the ET measurement is 0, it means that the center of the rim is 0mm from the car's hub.
The lower the ET measurement, the closer the center of the rim is to the car's hub.
Wrong ONE goal
If you choose rims with the wrong ET measurement, in the worst case scenario it could mean that they will either hit your fender edge, protrude beyond the fender edge or hit the inner fender, springs, shock absorber.
Really ONE goal
There is no 100% answer to what the right ET measurement is for your car. As it depends on the style you want to drive with. Some prefer the rims to sit all the way to the fender edge and others prefer the rims to sit a little inward from the fender edge.
Depending on your choice of style, you also need to keep in mind how the ET measurement is calculated, namely from the center of the rim to the outer edge. This means that if the rim width changes, then the ET measurement must also change.
For example, if you have 18" rims with a width of 7.5j and ET 45 on right now, then other 18" rims with a width of 8.0j and ET 45 will not fit like your current one. The new rims in 18x8.0j ET45 are 6.5mm further out towards the fender edge but also 6.5mm further in towards the inner fender.
The importance of the right ONE goal
As you have read above, the ET measurement is an important factor when it comes to rims. So how do you find the right ET measurement?
You can either use your current rim specs and go ahead with it if you think they fit perfectly, the way you want them, or you can use the guide below.
You need to know exactly what your current rims are before you can start calculating. If you don't know the measurements or it can't be seen on the rim, but the rims are original to your car, you can contact your local manufacturer car dealer and get the information there.
Information you need:
1. The width of the rim
2. ONE goal
3. Distance in mm from the outside of the rim to your fender edge
4. Distance in mm from the inside of the rim to whatever is closest. (shock absorber, springs, inner fender, etc.)
What style?
First you have to decide for yourself, what style do you want?
- All the way to the edge, so that the rim is flush with the edge of the screen
- The rims must fit under the screen edge
Calculation
Now that you have all the information you need, you can start calculating.
For example, your current rims are 19" 8.0j wide with ET 45 and you want your new rims to reach all the way to the fender edge. With your current rims, you have 15mm of space to the fender edge.
Then you can either find rims that have 15 less in the ET dimension, i.e. ET 30, or find rims that are wider than your current ones.
Some rims with a width of 9.0j and ET 42 will move the rims 15.5mm further out towards the fender but also 9.5mm further in towards the inner fender.
1.0 inch also written as 1.0j is 25mm, so if you go up 1 inch in rim width and keep the same ET measurement, it means that the rims now sit 12.5mm further out towards the fender edge and the inner fender.