Low offset fitment for a Z4 question

[Reach]

I saw a set of wheels for sale online that caught my eye.

Front - 18x8.5 15mm offset
Rear - 18x9.5 25mm offset

These offsets seem awful low compared to what I usually see quoted for Z4 series (in the 30-40 range). I'm curious to know if anyone thinks these wouldn't fit on my Z4, or if I added spacers to move them outward would they end up outside the fenders?

I am not lowered (stock sport suspension) and no plans to lower. I just want some nice wide rubber patches in the back for street fun.

Any thoughts?

[rehostman]

Hi.

To answer your question correctly we need to know your current wheel/offset specifications. The offset number is the distance in millimeters from the centerline of the wheel. A positive offset means the wheel hub is closer to the street side while a negative offset makes the wheel hub closer to the wheel well.

You need to calculate the distance from the wheel well for your current wheels and see if the new wheels will approximate this distance. Ideally you want a perfect match to avoid rubbing issues.

To calculate the distance to the wheel well for a wheel take the wheel width and divide it by 2, then multiply by 25.4. This will give you the centerline of the wheel in millimeters. Then add the offset to that number. That's the distance of the wheel hub from the wheel well.

Do the same calculations with your new wheels and see if they match your current wheels. For your case, the front wheel has a distance of 123mm (8.5/2*25.4 + 15). For the rear wheel you get a distance of 146mm (9.5/2*25.4 + 25).

Hope this helps.