fireice

Orig. 8 with 31mm offset compared to 8.5 with 25mm offset. Caculator indicates out 12mm or 1/2 inch.

My logic says a wash : in farther due to offset and out due to wider wheel.

xlr8tin

What is this for?

fireice

2001 E55

aintME

If I recall correctly, the lower the number for ET 25 vs 31, the further out the wheel will be towards the fender. For example, if you added a 5mm spacer to a wheel with a 40 offset, your effective offset would = 35? If I am correct, the wheel is not only 1/2 inch wider, but will sit out 6mm further than your original wheel.

ruBENZ

Offset is defined as the distance from the hub mounting surface to the centerline of the rim. Your calculator is correct. Well almost: 12.35 mm to be exact. A lower offset will always set farther out. In this case: 31 mm - 25 mm = 6 mm. As for the wider rim, the 0.5 " is divided between the inner side of the rim (0.25 ") and the outer side of the rim (0.25 "); 0.25 " = 6.35 mm. Thus, 6 mm + 6.35 mm = 12.35 mm.