offset?

[Burtonboarder950]

Now that i found my rim, I think i need to know what offset is haha. Can some one explain it and tell me what the offset is on our cars? Some site gives me a choice of 20 or 40.

[evildky]

offset relates hor far off center the hub mounting surface is fromt he center of the wheels, so the total amount of backspace a given offset yeilds will vary with the width of the wheel in question, a +25 offset on a 4" wide wheel leaves about 3" of backspace, a +25 offset on an 8" wheel yields 5" of backspace

[Burtonboarder950]

so given the choice of 20 or 40 offest, which one should i pick for my z?

[JETPILOT]

We need to know the width of the rim in order to answer that question, but likley the 20 would be better.