19 inch vs. 20 inch rims unsprung weight

templarklimek · 11-23-2013, 04:14 PM

Gents,

Just found out the rims on my inbound M6 are 19's. Is it true that the 19's with tires weigh less then 20's with tires and thus reduce unsprung weight?

I like the look of the 20's but weight is an enemy of this car already. Thanks for your advice.

RiverRunner · 11-23-2013, 10:53 PM

Why are you worried about the weight?

templarklimek · 11-24-2013, 08:39 AM

unsprung weight affects the "off the line" performance. Think of it like trying to sprint in a pair of boots or running shoes.

jeff4598 · 11-24-2013, 01:05 PM

It hugely effects handling feel, much more of an issue than acceleration as acceleration is somewhat traction limited any way and you floor it only now and then from a standstill but you constantly go around curves and corners!

templarklimek · 11-24-2013, 01:20 PM

so what is the better choice for performance 19 or 20? TY

noushy · 11-24-2013, 02:16 PM

Aftermarket HRE wheels are even lighter than factory 19 and 20 inch forged wheels. Can also do ceramic brakes and titanium bolts and lugs to drop weight even more. The Carbon Ceramic Brakes (ccb) drop 12 pounds per corner of unsprung weight, bolts 1 pound and wheels 2-5 pounds.

Peace
Noushy

templarklimek · 11-24-2013, 07:04 PM

Thank you Noushy, I've been reading about your M6. Simply uber awesome. Sadly, this was the only manual tranny M6 in the states and no carbon brakes. Is swapping the rotor/pads a possible future aftermarket option. I like the weight savings.

bjayfan · 11-25-2013, 06:39 AM

Quote:

Originally Posted by templarklimek

Thank you Noushy, I've been reading about your M6. Simply uber awesome. Sadly, this was the only manual tranny M6 in the states and no carbon brakes. Is swapping the rotor/pads a possible future aftermarket option. I like the weight savings.

If your car has 20" wheels you can add the CC brakes through M-Performance parts.

RiverRunner · 11-27-2013, 08:13 PM

Quote:

Originally Posted by templarklimek

Gents,

....

I like the look of the 20's but weight is an enemy of this car already. Thanks for your advice.

This was what I was referring to. If you've noticed, acceleration will not be effected by unsprung weight in the M6, traction is the problem. As for weight, you'll need to remove more than the weight of a 20" vs. 19" wheel to make a difference in acceleration. You want to drag race the car, put some slicks or Mickey Thompson drag tires on 16" wheels, and handling will go to heck, but you'll hook up. Taller sidewalls are better for drag racing, off the line traction.

TheSt|G · 12-04-2013, 02:47 PM

Even if they weigh the same, the smaller wheel will have an advantage in rotational inertia.

RiverRunner · 12-05-2013, 12:51 AM

Quote:

Originally Posted by TheSt|G

Even if they weigh the same, the smaller wheel will have an advantage in rotational inertia.

Not since the tire diameter is the same.

TheSt|G · 12-05-2013, 11:22 AM

Quote:

Originally Posted by PackerFan

Not since the tire diameter is the same.

You are assuming the radial weight distribution is equal, it isn't.

RiverRunner · 12-06-2013, 01:44 AM

Quote:

Originally Posted by TheSt|G

You are assuming the radial weight distribution is equal, it isn't.

The tire and aluminum rim weights are not much different, and will not impede the performance of this car's acceleration. If you've owned or driven one, you'd know that traction is the issue not rotational inertia or any related energy spent creating such inertia.

DreamerM6 · 12-06-2013, 04:21 AM

Quote:

Originally Posted by noushy

Aftermarket HRE wheels are even lighter than factory 19 and 20 inch forged wheels. Can also do ceramic brakes and titanium bolts and lugs to drop weight even more. The Carbon Ceramic Brakes (ccb) drop 12 pounds per corner of unsprung weight, bolts 1 pound and wheels 2-5 pounds.

Peace
Noushy

Please tell me where to buy it! Sounds like a good plan!

DreamerM6 · 12-06-2013, 04:24 AM

Ive put some Toyo R888 315/30/20 tyres on my M6 and traction is no longer a problem! improved 0-100 time by .05 sec on my M6! 4.2 to 3.7! Try it trust me youll be happy!

TheSt|G · 12-06-2013, 08:30 AM

Quote:

Originally Posted by PackerFan

The tire and aluminum rim weights are not much different, and will not impede the performance of this car's acceleration. If you've owned or driven one, you'd know that traction is the issue not rotational inertia or any related energy spent creating such inertia.

I have driven one, not a car for me.

Straight line acceleration is just one performance metric impacted by rotational inertia.

noushy · 12-06-2013, 02:16 PM

Quote:

Originally Posted by DreamerM6

Quote:

Originally Posted by noushy

Aftermarket HRE wheels are even lighter than factory 19 and 20 inch forged wheels. Can also do ceramic brakes and titanium bolts and lugs to drop weight even more. The Carbon Ceramic Brakes (ccb) drop 12 pounds per corner of unsprung weight, bolts 1 pound and wheels 2-5 pounds.

Peace
Noushy

Please tell me where to buy it! Sounds like a good plan!

The ti bolts can be had from Tikore in Florida. CCB upgrade package available through the dealer. HRE and most high end wheels can be had by several vendors here on the forum

11-23-2013, 04:14 PM	#1
templarklimek templarklimek 141 Rep 868 Posts Drives: 15' X6M, 12' R8 V10, Join Date: Jun 2008 Location: Houston Texas iTrader: (0)	19 inch vs. 20 inch rims unsprung weight Gents, Just found out the rims on my inbound M6 are 19's. Is it true that the 19's with tires weigh less then 20's with tires and thus reduce unsprung weight? I like the look of the 20's but weight is an enemy of this car already. Thanks for your advice.
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11-23-2013, 10:53 PM	#2
RiverRunner Second Lieutenant 16 Rep 277 Posts Drives: 2014 M6 Gran Coupe Join Date: Aug 2013 Location: The Southwest iTrader: (0) Garage List 2014 BMW M6 Gran Coupe [0.00]	Why are you worried about the weight? __________________ 2014 M6 Gran Coupe-Alpine White/Blk 2015 740i Sapphire Blk/Blk 2018 Tahoe RST 6.2 2019 Porsche 911 Turbo 991.2
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11-24-2013, 08:39 AM	#3
templarklimek templarklimek 141 Rep 868 Posts Drives: 15' X6M, 12' R8 V10, Join Date: Jun 2008 Location: Houston Texas iTrader: (0)	unsprung weight affects the "off the line" performance. Think of it like trying to sprint in a pair of boots or running shoes.
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11-24-2013, 01:05 PM	#4
jeff4598 Captain 172 Rep 676 Posts Drives: 2019 M2C HS, DCT, much Dinan Join Date: Jan 2009 Location: new jersey iTrader: (0)	It hugely effects handling feel, much more of an issue than acceleration as acceleration is somewhat traction limited any way and you floor it only now and then from a standstill but you constantly go around curves and corners!
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11-24-2013, 01:20 PM	#5
templarklimek templarklimek 141 Rep 868 Posts Drives: 15' X6M, 12' R8 V10, Join Date: Jun 2008 Location: Houston Texas iTrader: (0)	so what is the better choice for performance 19 or 20? TY
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11-24-2013, 02:16 PM	#6
noushy ///M Fan 1657 Rep 1,490 Posts Drives: M8 Comp, X5M Comp, iX M60 Join Date: Jul 2012 Location: Orchard Lake, Mi iTrader: (1)	Aftermarket HRE wheels are even lighter than factory 19 and 20 inch forged wheels. Can also do ceramic brakes and titanium bolts and lugs to drop weight even more. The Carbon Ceramic Brakes (ccb) drop 12 pounds per corner of unsprung weight, bolts 1 pound and wheels 2-5 pounds. Peace Noushy __________________ 2019 BMW X5 50i Mineral White/Tartufo all options including M Sport 2022 Porsche 911 C4S Silver/Brown 2023 BMW iX M60 Black Sapphire/Amido, Titanium Bronze trim/22 2023 Audi RS6 Avant Daytona Gray/Black 2024 BMW X5M Comp Brooklyn Gray/Taruma Brown, Titanium Exhaust on order
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11-24-2013, 07:04 PM	#7
templarklimek templarklimek 141 Rep 868 Posts Drives: 15' X6M, 12' R8 V10, Join Date: Jun 2008 Location: Houston Texas iTrader: (0)	Thank you Noushy, I've been reading about your M6. Simply uber awesome. Sadly, this was the only manual tranny M6 in the states and no carbon brakes. Is swapping the rotor/pads a possible future aftermarket option. I like the weight savings.
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12-04-2013, 02:47 PM	#10
TheSt\|G Resident Tamed Racing Driver 298 Rep 4,697 Posts Drives: 911, 130is, E39 M5, E36 M3 Join Date: Mar 2008 Location: Outside Philly iTrader: (2)	Even if they weigh the same, the smaller wheel will have an advantage in rotational inertia.
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12-06-2013, 04:24 AM	#15
DreamerM6 Private First Class 28 Rep 129 Posts Drives: BMW F13 M6 Join Date: Jan 2013 Location: South Africa iTrader: (0)	Ive put some Toyo R888 315/30/20 tyres on my M6 and traction is no longer a problem! improved 0-100 time by .05 sec on my M6! 4.2 to 3.7! Try it trust me youll be happy!
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