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[roadburn]

Elsewhere on this forum, I posted excerpts from a Grassroots Motorsports test of the 135i (they loved it):
http://www.1addicts.com/forums/showthread.php?t=3177

But there's another story of interest in the same Feb. 2008 issue -- an on-track test of larger-wheel set-ups conducted on a late-model 325i. The mag track-tested 3 different combinations:

Plus Zero: Better tires (Yokohama S.drive 205/55R16) & regular 16-inch wheels.
Plus One: 205/50R17 Yokos & 17x8 ASA wheels.
Plus Two: 225/50R18 Yokos & 18x8 ASA wheels.

GRM summed it up: "Here's a shocker for those hailing from the bigger is better camp: The 18s didn't win this little comparo."

The 18-inch set-up was several tenths slower than the 17s on track, the mag said, with "a noticeable reduction in braking performance, unfortunately, as we could feel the extra mass fighting the car."

The 17-inch wheels were the sweet spot: "Overall, the 17-inch combination felt the best of the three. This package had a good balance of responsiveness, stability, cornering traction and braking capability." (It also was the fastest.)

Maybe this should be food for thought for all the guys planning to go for the optional 18-inch wheels on the 135i (or 22-inch aftermarket spinners, or whatever).

Big wheels may look great at the drive-in, but keep 'em off the track....

[Wolfpack]

Those of us that track our BMW's already know this and went for the 17" track wheels. On the street, it makes no appreciable difference, but on the track, you can really tell. The other benefit is that there is typically a better selection of 17" track rubber and the prices are better to boot. A win/win all the way around.