hmmm thought magnesium was lighter then alloy/aluminum?
08-13-2009, 06:16 PM
#21
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St. Jude Donor '03
If the identical wheel was made in both materials, the magnesium would definitely be lighter, yes.
But that's not the case, the C5 mag wheel has a lot more material to it, and 17.5 lbs of magnesium will always weigh 1/2 lb more than 17 lbs of aluminum.
But that's not the case, the C5 mag wheel has a lot more material to it, and 17.5 lbs of magnesium will always weigh 1/2 lb more than 17 lbs of aluminum.
08-13-2009, 06:28 PM
#22
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Extremevette in your other thread about whether your wheels were polished or chrome it was brought up and you never heard of this? Seems GM may have dodged the recall issue but it has been reported on this forum since like 2005 or so. great detailed pics in Blackpixi7's thread.
08-13-2009, 08:39 PM
#24
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thanks for the input...m car has already been tuned...I just don't want to lose anything that I already have. Iam a bit confused on the whole rotating mass thing. I have read so many posts from guys saying it matters a lot and that they can feel the difference from just switching out stock for repros. I don't want to feel loss in hp/tq.
If it's all about 1/4 times then put on some 16s or 17s and have at it.
And I'd much rather be looking good.
08-13-2009, 09:00 PM
#25
Team Owner
I couldn't feel a SOTP difference switching to CCW 505As and non-runflats. The combo is not that much heavier than stock anyway. Then there is the vastly improved traction factor. I can more effectively put the power to the pavement and hang onto corners much better with this combo than with my smaller, harder runflats. I can drift easily around any corner at will in my wife's runflat-shod, less powerful C5.
08-13-2009, 09:41 PM
#28
Melting Slicks
I've got the Magnesium Rims on my 2004 Vette and get a lot of compliments on them. No issues with chipping, cracks or spontaneous combustion! A lot of people say they won't get them because they will burn but you'd have to get them to well over 1,000 F. Pure Magnesium ignites at 883 °F the rims are a magnesium alloy...
I like the Magnesium look, personally I'm sick of the big BLING rims...
I like the Magnesium look, personally I'm sick of the big BLING rims...
thinspokes do crack...ask me how I know
08-14-2009, 09:06 AM
#30
Le Mans Master
It is not ONLY the weight, but also the radial location of it that affects performance (due to radial moment of inertia).
The closer the weight to the center of the wheel, the less affect (at least for acceleration). Tire weight matters more than wheel weight due to this. Putting on 22 inch wheels would affect performance greatly, this is why they often upgrade brakes when using a much larger wheel.
The closer the weight to the center of the wheel, the less affect (at least for acceleration). Tire weight matters more than wheel weight due to this. Putting on 22 inch wheels would affect performance greatly, this is why they often upgrade brakes when using a much larger wheel.
08-14-2009, 09:13 AM
#31
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well to add some additional data...just weighed in my rears as well.
54 pounds total.
36 pounds for the Kumho runflat tires
18 pounds a piece for rims
I can see why this is a pretty good combo and is a best seller on tirerack. Pretty light combo for a runflat package.
54 pounds total.
36 pounds for the Kumho runflat tires
18 pounds a piece for rims
I can see why this is a pretty good combo and is a best seller on tirerack. Pretty light combo for a runflat package.
08-14-2009, 09:20 AM
#33
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It is not ONLY the weight, but also the radial location of it that affects performance (due to radial moment of inertia).
The closer the weight to the center of the wheel, the less affect (at least for acceleration). Tire weight matters more than wheel weight due to this. Putting on 22 inch wheels would affect performance greatly, this is why they often upgrade brakes when using a much larger wheel.
The closer the weight to the center of the wheel, the less affect (at least for acceleration). Tire weight matters more than wheel weight due to this. Putting on 22 inch wheels would affect performance greatly, this is why they often upgrade brakes when using a much larger wheel.
My logic is to switch the runflats to a standard (lighter tire) to do what OLDVETTER is talking about. (reducing the weight from the outerpart of the total circumference). The rim weight on a repro is 6-9lbs heavier over stock. Now change runflats to non runflats and your looking at a savings of around 4-6lbs per tire so looks like the additional weight of the rim (of around (+)6-9lbs) would be more toward the center of the hub and the loss of weight of the tire (of around (-)4-6lbs) would be further away from the rim where you want it.
I don't know however how much impact the weight affects acceleration going further from the center (out the 8 or so inches) but common sense would be it should matter to some degree.
So far all pretty much common sense logic only... it would be cool to see some real world data from a person good with math and the physics behind all this.
Last edited by XtremeVette; 08-14-2009 at 09:37 AM.
08-14-2009, 11:28 PM
#34
Safety Car
08-22-2009, 01:06 AM
#35
As others have pointed out, the rotational mass of the wheels is the real issue here. Taking 5 lbs of weight out of your car will not have the same impact as removing 5 lbs of weight from your wheels.
There is a reason why so many racers worry about things like lightweight flywheels, carbon fiber driveshafts, lightweight brake rotors, and lightweight wheel/tire combinations. Remember that an object at rest tends to remain at rest. Also remember that a heavier object is more difficult to put into motion than a lighter object.
To illustrate this point, consider a bicycle wheel versus a car wheel. Which one is easier to spin up to speed using the same amount of force is obvious...
Heavier wheels hinder a vehicle's ability to accelerate and decelerate quickly. That's why you might as well be taking horsepower out of your car when you bolt on heavy aftermarket wheels.
Another interesting point not yet brought up in this thread is how unsprung weight can degrade a vehicle's handling characteristics.
LO PHAT
There is a reason why so many racers worry about things like lightweight flywheels, carbon fiber driveshafts, lightweight brake rotors, and lightweight wheel/tire combinations. Remember that an object at rest tends to remain at rest. Also remember that a heavier object is more difficult to put into motion than a lighter object.
To illustrate this point, consider a bicycle wheel versus a car wheel. Which one is easier to spin up to speed using the same amount of force is obvious...
Heavier wheels hinder a vehicle's ability to accelerate and decelerate quickly. That's why you might as well be taking horsepower out of your car when you bolt on heavy aftermarket wheels.
Another interesting point not yet brought up in this thread is how unsprung weight can degrade a vehicle's handling characteristics.
LO PHAT
