Gizmo

Can anyone explain in the simplest of terms what the wheel offset numbers are about, and what implication they have for swapping out other rims on our E60's ???

Specifically, I'd like to acquire the new ///M wheel style 166 when they become available, as they look hot and are a bit bigger than the style 124's I've got now. At 19", I figured I wouldn't have to worry about wheel well rubbing or suspension alteration and the like. However, the specs on the 166ers note front/rear ofsets of ET12/28 while the ofsets for the 124's are ET20/32.

Thanks...

ch7656

Here's a wheel offset calculator that I have found useful in the past / Punch in existing width and offset and the same for the new wheels and it'll tell you exactly what the difference will be

Wheel offset calculator

JBOO

If you get the wrong offset, the face of your wheels can either be too far out from the side of your car or too far in. Hope that makes sense.

Gizmo

Thanks... The calculator doesn't take into effect the wheel height differences - how might that influence things ??? Also, if I calculate that the wheel is closer to the hub or will extend laterally by some amount, how do I know if that is OK or not ???

I dont want to be the guy having to turn my new BMW ///M wheels into a coffee table (like we witnessed on ebay a month or so ago) !!!

Gizmo

What are the general tolerance limits (how much closer can the rim get to the central hub, or extend outward, before being a problem) ???

Thanks...

colejl

The height the wheel as such does affect the offset. The offset is the measurement from the centre of the rim to where the wheel fits to the hub in mm.

Increasing the offset will cause the wheels to be inset more and decreasing the offset will make them stick out more. An increased offset can be fixed with spacers but a decreased offset cannot be adjusted.

A few mm each way probably won't make a huge difference but anything more than about 5mm could make a big difference.

cobradav

Don't forget, wheel offset can also affect brake caliper clearance as well. Most reputable mfr's of wheels offered for specific applications will know and plan for clearance even though they may be offering an offset that differs from the OEM wheels.