Can someone please define "offset" in plain English? What do the numbers mean? How does a wheel with higher offset look compared to a wheel with a lower offset? How can I find the offset of my stock rims? Thanks.

Offset is the distance from the vertical plane of the centerline of the wheel, to the vertical plane of the surface that contacts the hub (actually the brake rotor). It is expressed as positive offset if the center line is inboard of the mounting surface (like BMW wheels), and negative if it is outboard.

"Deep dish" wheels are an example of negative offset. I don't know how to find out the offset of BMW wheels without measuring one. Maybe someone can tell us.

So negative offset causes the wheel to stick out more? I'd like to get rims that fill the wheel well nicely without actually sticking out past the fender. Is the offset the oly masure I should be concerend about when thinking about this particular feature of the wheel fitment?

Just go to tirerack.com, enter your car and click on wheels. They have a great selection of wheels for your car(s). Yes, you want a similar offset and the same bolt pattern too. But they'll match wheels to yours.

http://www.tirerack.com/images/wheels/tech/offset.gif

http://www.tirerack.com/wheels/tech/techpage.jsp?techid=101

So negative offset causes the wheel to stick out more? I'd like to get rims that fill the wheel well nicely without actually sticking out past the fender. Is the offset the oly masure I should be concerend about when thinking about this particular feature of the wheel fitment?

The lower the offset number, the more the wheel will stick out. You also need to be concerned about wheel width, as it can affect the offset to get correct fitment. Tire Rack is a good starting place as the wheel/tire packages are correct fitments. If your car is lowered, some of these combo's will still be OK, but you can find out what people here are running on their modified cars.

Can someone please define "offset" in plain English? What do the numbers mean? .


The lower the offset number, the more the wheel will stick out. You also need to be concerned about wheel width, as it can affect the offset to get correct fitment. Tire Rack is a good starting place as the wheel/tire packages are correct fitments. If your car is lowered, some of these combo's will still be OK, but you can find out what people here are running on their modified cars.

Holy crap guys, It took 6 posts for someone to give him in English what offset is.

Lets start at zero. Look at the post that Daved made.

Zero offset is when the mounting surface of the wheel is EXACLTY in the middle of the wheel.

Positive offset is when the mounting surface is pushed toward the fender. Mostly all (cannot think of one that isnt off the top of my head) stock auto's have positive offset mainly around et40. 40 is the measurement in mm from the center of the wheel to the mounting surface.

Ideal offsets for the

e36 and e46(non M) are +41 (stock) to +35.
e39,e34,e30,older 6'ers etc have a +20 offset (They stick out farther from the hub) there for will not work on e36 or e46 cars without some extensive fender rolling and pulling and small tires(Called stretching which gives more clearence, which is not recommended by most but loved by others. Very "EURO")

The M Roadster and M coupe have offsets of +41 front and +8 in the rear.

e46 m3 has +41 front and +20 rear

As you can see, all positive offsets.

Negative offset, you guessed it, is when the mounting surface in to the strut side of the wheel. These wheels are usually extremely deep and have large lips.

You also need to be concerned about center bore and tire sizes. If you have a question about these, just ask (or search since it is so easy)
Hopefully this is more "English" to you

Very helpful Karl. Thank you. I was confused as well