Originally Posted by TAL2GK
I've got a stock non-M 2.5i I've owned since new 2003 and am impressed with your wheels. Truthfully, mine has always been a street-only ride and I'm looking at 18" diameter. What setup would you recommend and does tire size affect availability and options when buying rubber?
Also, would you recommend the ARC-8 or EC-7 for a street Z4? I really don't understand the difference between the two. Thanks!
Either wheel will work great on your Z4 but there are some slight differences between the two wheels that could be a deciding factor. The EC-7 is our newest wheel with a few new sizes that would work really well on your Z4, better than the ARC-8 too. The EC-7 has a little bit better big brake fitment and has a stronger wheel face than the ARC-8 wheel.
The ARC-8 is usually a couple lbs lighter per wheel and has straight spokes compared to the EC-7's curved spokes.
If you were to go with the EC-7's I would suggest an 18x8.5" ET35 front wheel with a 235/40/18 tire and an 18x9.5" ET43 rear wheel with a 265/35/18 rear tire. The 18x9.5" ET43 is a new size to us that is a higher offset 9.5" wheel allowing you to use wider rear tires than with the ARC-8 wheel.
If you were to go with the ARC-8's than I would suggest an 18x8.5" ET38 front wheel with a 235/40/18 tire and an 18x9.5" ET35 rear wheel with a 255/35/18 rear tire. The ARC-8's lower offset limits your rear tire width but the wheels would be lighter overall.