to the innermost, i.e., inside edge, of the wheel. For a 29 mm offset, the Back Spacing would be approximately:

BS = (9.0 + 1.0)/2 + 29/25.4 = 6.14 inches

You add 1 inch to the wheel width because almost all wheels are 1 inch wider in overall width.

Back spacing is normally used to determine whether a particular wheel will clear suspension and body components, not necessarily brake components. The design of the wheel spokes determines brake caliper clearance.

For instance, the rear wheel offset on my Porsche Technology wheels is 65 mm, which means the majority of these 18x10 wheels is towards the inside of the car. Wide body 911s use 40 mm offset, which would move the wheel too far out and hit the fender.

I have to say these RS4 wheels are quite heavy if they weigh 27.6 lbs. A good forged wheel would be about 5 lbs lighter, which would be very noticeable.

Tom, Seattle area
2003 A4 1.8TQM Denim/Ebony | Prem | Cold | Sport | Xenon | Bose | APR 1+
2003 Honda Civic Si Vivid Blue | 17" OZ w/Eagle F1 | Mugen Sports Suspension | HFP Body Kit
1990 Porsche 944 S2 Guards Red | too many mods | http://www.944s2.com