Weight Reduction - Page 3 - Alfa Romeo 4C Forums
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post #21 of 27 (permalink) Old 04-13-2017, 05:36 AM
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Originally Posted by Alipapa View Post
As I said in my post about my last track day. having an extra passenger (140-150 lbs) in car took me about extra 4-6 cars length to stop the car.
Just imagine how much farther it would have been if you had the North American version of a passenger? Our passenger come with a lot more um, crash protection.
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post #22 of 27 (permalink) Old 04-13-2017, 05:38 AM
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Originally Posted by Matt Leavitt View Post
Regarding the wheels, the 17/18 combos get the weight down the best. The Advan RS2's we sell at Alfa9 Supply are the lightest you can get... short of spending the money for carbon rims! They are flow-formed and made in small batches, with excellent quality and 2 colors, semi-gloss black and metallic hyper black... Fronts 16.2 pounds each Rears 16.9 pounds each and a very close second in weight are the O.Z. Alleggerita's... Fronts are 15.8 lbs. Rears are 19.2 lbs.
I was surprised how ineffective the wheel swap was for dropping weight. I replaced the OEM 18/19s with the Alleggerita's and total weight reduction (including tires) was only 3.2 lbs. (0.4 lbs. for each front, 1.2 lbs. for each rear). It seems the reduced wheel weight was offset by heavier tires (RE-71Rs with higher profiles). What did you do to your 4C today? However, I still highly recommend doing something like this on a track car. Much better tires and you don't beat up your OEM rims.
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Last edited by hornetball; 04-13-2017 at 05:40 AM.
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post #23 of 27 (permalink) Old 04-13-2017, 07:11 AM
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To swap the rims is very effective !!

The weight reduction from the OEM 18+19 to the Advan 17+18 were 9.25 Kg

The weight reduction is one part the other one is the gyroscope loads

The front Alleggerita is lighter than the Advan
Price weight ratio very competitive !!
[IMG][/IMG]
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post #24 of 27 (permalink) Old 04-13-2017, 11:56 AM
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To swap the rims is very effective !!
I disagree. Not nearly as effective as it has been on my other cars. This is not an opinion or a spreadsheet (my spreadsheet looked just like yours, BTW), I'm simply reporting my real-world experience which includes tire weight. As for reduced Moment of Inertia -- there is a theoretical gain there but it's not really noticeable in the data. The added grip of better tires is noticeable everywhere though.

Bottom line for me, the OEM wheel/tire combination is unusually lightweight. Including tire weight, you will save less than 4 lbs. by going to Allegeritas. Thems the facts . . . . Sorry if you don't like them.
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post #25 of 27 (permalink) Old 04-13-2017, 12:34 PM
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As said above, Alleggerita rims are light but track day tyres are stiffer constructions than road tyres, therefor the net weight savings is limited. The grip and road holding improvement is huge though, nothing less.
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post #26 of 27 (permalink) Old 04-13-2017, 12:36 PM
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Originally Posted by hornetball View Post
I disagree. Not nearly as effective as it has been on my other cars. This is not an opinion or a spreadsheet (my spreadsheet looked just like yours, BTW), I'm simply reporting my real-world experience which includes tire weight. As for reduced Moment of Inertia -- there is a theoretical gain there but it's not really noticeable in the data. The added grip of better tires is noticeable everywhere though.

Bottom line for me, the OEM wheel/tire combination is unusually lightweight. Including tire weight, you will save less than 4 lbs. by going to Allegeritas. Thems the facts . . . . Sorry if you don't like them.
I'll try to corroborate your fact shortly, but I believe it.

On other cars, there has been a significant weight savings in swapping to a lighter weight wheel of the same or even sometimes one size larger racing wheel.
So, there would be no more rubber, and possibly even less. The savings is in the wheel,
In our case there is a somewhat misleading weight saving in that the wheel is 10% smaller in diameter, but we're putting the same OD rubber on (so, as you say, a significantly larger and heavier tire).

Putting the lightweight Ultraleggerra 18"/19" wheels on may well result in a significant improvement over stock 18"/19" as the rubber is the same, but I don't recall the wheel weights on those.
Putting the Alleggrita 17"/18" on in place of the stock 17"/18" is also likely a weight savings, as again the tire is the same. I don't have the weights of those stock sizes handy right now either.

ALSO, don't forget that the P-Zeros are a bit "optimistic" in their tread width measurement. 205 is more like 200. So they are most likely going to be lighter than a tire that has a true 205 mm tread width. Plus, a number of people have gone to a wider tread with the new wheels, which likely makes sense from a performance perspective, but spoils a true weight comparison.
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Last edited by 4Canada; 04-13-2017 at 12:44 PM. Reason: Clarified Sizing
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post #27 of 27 (permalink) Old 04-14-2017, 06:49 PM
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Originally Posted by hornetball View Post
I was surprised how ineffective the wheel swap was for dropping weight. I replaced the OEM 18/19s with the Alleggerita's and total weight reduction (including tires) was only 3.2 lbs. (0.4 lbs. for each front, 1.2 lbs. for each rear). It seems the reduced wheel weight was offset by heavier tires (RE-71Rs with higher profiles). What did you do to your 4C today? However, I still highly recommend doing something like this on a track car. Much better tires and you don't beat up your OEM rims.
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I'll try to corroborate your fact shortly, but I believe it.
...
OEM 18" teledial fronts with stock P-Zero's less than 1/2 worn = 36 lbs
OZ Alleggrita 17" front with 215 Toyo 888R, probably over 1/2 worn = 36 lbs.
My scale is not ultra accurate, but pretty close.

I weighed the OZ rears with 245 Toyo's at 42lbs, but did not pull a stock rear wheel (somebody can probably supply the stock weight. Betting they are the same.

So, no apparent significant weight savings on the smaller/lighter wheel combo once you put the taller rubber on.

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