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      09-18-2012, 09:01 AM   #5
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Drives: 2010 e92 M3
Join Date: Sep 2009
Location: Houston, Texas

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2010 BMW M3 e92  [4.67]
1998 BMW M3  [4.25]
Originally Posted by Protocav View Post
I assume that when you talk about an R40SC you mean "why are the R40's so flat?"

The simple answer is: while the curved spokes are more beautiful to look at, the most efficient design in terms of strength and weight is a straight beam, especially in buckling, which is the mode of loading that the vertical spoke is seeing (and bending when the vehicle is in a turn). Any curved or extra material is only adding weight. The really tall backpad is required to reach the low offset that the M3 is able to run, so the gigantic bowl in the center is designed to remove the mass that is not required for strength. The R40/43 is designed first to be light and strong, and then second to look good. As far as i know, they are lighter than the Apex wheels also. Keep in mind that HRE could easily make these wheels weigh 15 lbs, but they are very conservatively load rated for our heavy cars to go around the track for years. Most race teams throw their wheels away at the end of the season, but that would be unacceptable for the consumer market.

I have the R43's and would certianly like them to be a little more concave...however, when i look at them the beauty is in the engineering for me.

Thanks for the input. I know why they would do the flat design. But for a wheel that is also on the public market, not just race teams. Id say add a slight concave or even a specific design model ( SC ) to suit the occasional tracker that wants nice wheels daily too... Just a thought. Cause again, Id be all over a set if they were even slightly concave.
"Out of pure habit, I gave a black M3 a point by on the way home from work this evening." - ThunderMoose