02-03-2011, 12:56 PM | #24 | |
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Furthermore, these weights for OEM street car rims are not bad at all. BMW can't put pure racing wheels that will bend and crack in 40k miles and require a warranty replacement or even worse, a law suit. Even the OEM 350z Nismo "lightweight" rims by Rays engineering are 29 lbs for a 19x10. |
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02-03-2011, 01:12 PM | #25 | |
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They are 1 piece forged wheels, IIRC with tires Im under 50lbs per wheel (I wanna say 45-46, I had written it down somewhere). I have another set of wheels for my other car again 19X13 and those may have been the 21lbers. The car isnt housed here so I cant verify that. |
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02-03-2011, 05:18 PM | #28 | |
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Now imagine shaving off 10 lbs off each corner. Yes, wheel weight is a big deal. Unsprung weight by itself (shocks, suspension components, brake calipers) is a 4x ratio IIRC. |
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02-03-2011, 09:29 PM | #29 | |
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02-03-2011, 10:21 PM | #30 |
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Well i'm not sure where the 10x comes from but the general principal has to do with the moment of inertia (MOI) / angular momentum. MOI is the amount of force required to change the angular momentum of an object about a fixed axis, or change the axis of rotation. These are what "gyroscopic" forces are.
When you accelerate/brake/turn, not only are you changing the velocity of the wheel (as if it were in your trunk) but you must change the angular velocity AND also the axis of that velocity, which both require significant energy. Think about when you're holding a spinning bike wheel by the hub, how hard it is to change the orientation... And that's 3-4 pounds at a relatively slow angular velocity.. Now take 60 lb car wheel/tires, multiply that by 4 corners, at 20-100mph... That is a significant moment of inertia. I think the 10x is a pretty rough guesstimate though, not sure where that came from. |
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02-04-2011, 04:19 AM | #32 | |
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I don't think it's that simple. For sure it's always good to cut mass wherever you can, especially in rotational and non-rotation un-sprung mass... but I think on a road car, it's primary use is in the bar, not on the track! :-) |
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02-04-2011, 04:23 AM | #33 | |
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02-04-2011, 09:12 AM | #34 | |
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Odd how the 18" G-Spyder rims from Lexus weigh 25 pounds, but look to be less. I've been searching for "Y" spoked rims that are similar to the Neez or BBS CSLs, but not CSL knockoffs...it is hard to find fitments in that design for the IS300. |
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02-05-2011, 02:00 AM | #36 | |
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02-05-2011, 11:12 AM | #37 |
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I dont know anything about TUV certification, but the 18 inch version of that wheel was tracked regularly by many people in high HP applications.
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02-05-2011, 11:58 AM | #38 | |
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http://www.wheelkinetics.com/html/forgeline/ http://forums.viperclub.org/new-prod...lus-tires.html Contact Forgeline on Monday, they have live chat on their site and Im sure they can verify the weight AND no, I wasnt talking about Viper drag racing, but ya numerous people have dragged those wheels. |
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02-05-2011, 05:14 PM | #39 | |
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http://www.kulchawheels.com/alloy_wh...n/standard.php At any rate.. Neech said it exactly.. any wheel BMW puts on a car has to have a warranty behind it for 4/50K miles, and be subjected to all sorts of abuse, as well as pass more stringent specifcations than what an aftermarket supplier has to do. So it's really easy to see why going with super light wheel is NOT something a manufacturer is going to lose a lot of sleep over doing. If you feel the stockers aren't light enough, sell them and get an aftermarket wheel. These days, it seems like you can't find an E46 M3, E9x M3. or other cars like the Nissan 370Z with a set of stock wheels on them anyway since so many owners go aftermarket anyway. Last edited by M3 Adjuster; 02-05-2011 at 05:19 PM.. |
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02-06-2011, 01:24 PM | #40 | |
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03-19-2013, 08:45 AM | #43 | |
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On a side note, it is very cool when a truck shows up at your house and delivers a PALLET of rims... |
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03-23-2013, 10:49 AM | #44 | |
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