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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Wheels and Tires Forum Sponsored by The Tire Rack > Unsprung weight from wheels



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      02-29-2012, 12:43 PM   #1
sdstatestud88
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Exclamation Unsprung weight from wheels

Just a little blurb I saw in European Car

"What you need to know is that changing to tires that are 1 lb heavier will effectively add 8 lb to the car (four tires, remember) and that adding a pound to the wheels will effectively add somewhere around 6 lb to the car."

Read more: http://www.europeancarweb.com/tech/0...#ixzz1nnHB34FA
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      02-29-2012, 01:45 PM   #2
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This is nothing new, but i applaud you for sharing it with the community as i think most people dont know this.
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      02-29-2012, 02:35 PM   #3
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I figured it wasn't new but I have seen different people give different answers as well as people always asking
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      02-29-2012, 03:04 PM   #4
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Preaching to the choir for me!

Many, many, many of people on here are more worried about looks.

Thanks for posting.
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      02-29-2012, 03:44 PM   #5
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Quote:
Originally Posted by AW325xi View Post
Preaching to the choir for me!

Many, many, many of people on here are more worried about looks.

Thanks for posting.
Currently I have VMR 718 19'' but will probably be going to an 18'' sub 20lbs but am on a budget...There are a few options though
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      02-29-2012, 03:59 PM   #6
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Quote:
Originally Posted by sdstatestud88
Quote:
Originally Posted by AW325xi View Post
Preaching to the choir for me!

Many, many, many of people on here are more worried about looks.

Thanks for posting.
Currently I have VMR 718 19'' but will probably be going to an 18'' sub 20lbs but am on a budget...There are a few options though

Remember to factor in tire weight as well.
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      02-29-2012, 04:03 PM   #7
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Dont cheap out and forget about the super weight savings of titanium studs and lug nuts. Cornering and light throttle response is much more crisp going to work everyday.
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      02-29-2012, 04:08 PM   #8
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Quote:
Originally Posted by Lulz_M3 View Post
Remember to factor in tire weight as well.
Im running V12s. Assuming I run them again I will be getting a smiller tire Diameter but more rubber so maybe they will be roughly the same weight..According to tirerack the weight will be +/- 1-2 lbs per tire
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      02-29-2012, 04:27 PM   #9
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Using heavy parts makes your car heavier and slower? No way.
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      02-29-2012, 05:29 PM   #10
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Quote:
Originally Posted by Pcemkr View Post
Using heavy parts makes your car heavier and slower? No way.
This is specifically about unsprung weight and the debate of what is the ratio of unsprung weight difference compared to regular weight. Some say 1:10 some say 1:8 etc...

No need for the sarcasm and smart ass remarks
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      03-01-2012, 12:53 PM   #11
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While this may surprise some, the weight of a tire is actually a poor indicator of a tire's real world performance. Using tire weight as an important factor to consider when buying a tire sounds beneficial in theory, but other factors like grip, handling, and steering response have a much greater effect on performance. I've been testing tires on identically setup BMW test cars for over ten years and have found no correlation between tire weight and real world handling on the track or on the street.

Sometimes the heaviest tire will have the best handling and fastest autocross times in a given test; sometimes the lightest tire will. Just one example of the lightest tire performing the worst in a test would be in a recent test is a test of extreme performance summer tires, which many use for autocross. In this test the lightest tire, the Kumho ECSTA XS, came in dead last, while the heavier Bridgestone RE11 and Yokohama AD08 were better. (link to test http://www.tirerack.com/tires/tests/...iate=FH8<br />. )

Keep in mind that while wheel weight can be an important factor to consider, tire weight should actually be one of the last things to consider when making a tire purchase decision. Dry grip, wet grip, and steering response are more far important factors for an enthusiast trying to maximize performance.
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      03-01-2012, 01:28 PM   #12
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Quote:
Originally Posted by Gary@TireRack View Post
While this may surprise some, the weight of a tire is actually a poor indicator of a tire's real world performance. Using tire weight as an important factor to consider when buying a tire sounds beneficial in theory, but other factors like grip, handling, and steering response have a much greater effect on performance. I've been testing tires on identically setup BMW test cars for over ten years and have found no correlation between tire weight and real world handling on the track or on the street.

Sometimes the heaviest tire will have the best handling and fastest autocross times in a given test; sometimes the lightest tire will. Just one example of the lightest tire performing the worst in a test would be in a recent test is a test of extreme performance summer tires, which many use for autocross. In this test the lightest tire, the Kumho ECSTA XS, came in dead last, while the heavier Bridgestone RE11 and Yokohama AD08 were better. (link to test http://www.tirerack.com/tires/tests/...iate=FH8<br />. )

Keep in mind that while wheel weight can be an important factor to consider, tire weight should actually be one of the last things to consider when making a tire purchase decision. Dry grip, wet grip, and steering response are more far important factors for an enthusiast trying to maximize performance.
Definitely agree with you. I wouldn't factor in tire weight for your exact reason stated. I will always look for upper mid to excellent performing tire
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      03-02-2012, 11:00 PM   #13
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Quote:
Originally Posted by Gary@TireRack View Post
While this may surprise some, the weight of a tire is actually a poor indicator of a tire's real world performance. Using tire weight as an important factor to consider when buying a tire sounds beneficial in theory, but other factors like grip, handling, and steering response have a much greater effect on performance. I've been testing tires on identically setup BMW test cars for over ten years and have found no correlation between tire weight and real world handling on the track or on the street.

Sometimes the heaviest tire will have the best handling and fastest autocross times in a given test; sometimes the lightest tire will. Just one example of the lightest tire performing the worst in a test would be in a recent test is a test of extreme performance summer tires, which many use for autocross. In this test the lightest tire, the Kumho ECSTA XS, came in dead last, while the heavier Bridgestone RE11 and Yokohama AD08 were better. (link to test http://www.tirerack.com/tires/tests/...iate=FH8<br />. )

Keep in mind that while wheel weight can be an important factor to consider, tire weight should actually be one of the last things to consider when making a tire purchase decision. Dry grip, wet grip, and steering response are more far important factors for an enthusiast trying to maximize performance.
+1
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      03-03-2012, 08:23 AM   #14
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Thanks for the info Gary. I never really looked at tire weights, just performance and your tests have been a fantastic tool!
I'm running Michelin PSS purchased from Tirerack (actually I've been buying all my tires from Tirerack for about 10 years), I am very happy with them!
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      03-03-2012, 09:35 AM   #15
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The nice thing about switching from RFTs to normal tires, aside from the ride, is that regular tires are always lighter by several pounds. You can absolutey feel the difference between a 30 pound runflat and a 23 pound normal tire when accelerating from a stop.
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      03-03-2012, 02:57 PM   #16
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Better op for lighter forged wheels instead.
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      03-03-2012, 03:47 PM   #17
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Quote:
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Better op for lighter forged wheels instead.
That's the thing, saving weight from the tire makes more difference than saving weight from the wheel itself--a lot more.
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      03-03-2012, 05:21 PM   #18
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Great post. I'm kicking around the idea of replacing my wheels in order to drop un-sprung weight. I can drop roughly 6 lbs per wheel, going from my type 161s to lightweight replacements...but I wonder, is it worth the 1k+ cost .... will I really see a measurable change in performance?

Has anyone out there tried to measure the benefits in terms of acceleration, braking, gas mileage etc? I know Car and Driver (with TireRack's help) put something together showing a trade-off for larger diameter wheels (due to weight increase); does anyone else have before and after experience they can share regarding the benefits of lowering weight?
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      03-03-2012, 06:02 PM   #19
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Quote:
Originally Posted by mlifxs View Post
Great post. I'm kicking around the idea of replacing my wheels in order to drop un-sprung weight. I can drop roughly 6 lbs per wheel, going from my type 161s to lightweight replacements...but I wonder, is it worth the 1k+ cost .... will I really see a measurable change in performance?

Has anyone out there tried to measure the benefits in terms of acceleration, braking, gas mileage etc? I know Car and Driver (with TireRack's help) put something together showing a trade-off for larger diameter wheels (due to weight increase); does anyone else have before and after experience they can share regarding the benefits of lowering weight?

In actual Quarter mile times etc you might gain 1mph and a 1/10 second but nothing real special. Getting new rims in your case though can be both aesthetic and functional (greater width etc)
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      05-09-2012, 09:30 PM   #20
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Quote:
Originally Posted by Gary@TireRack View Post
While this may surprise some, the weight of a tire is actually a poor indicator of a tire's real world performance. Using tire weight as an important factor to consider when buying a tire sounds beneficial in theory, but other factors like grip, handling, and steering response have a much greater effect on performance. I've been testing tires on identically setup BMW test cars for over ten years and have found no correlation between tire weight and real world handling on the track or on the street.

Sometimes the heaviest tire will have the best handling and fastest autocross times in a given test; sometimes the lightest tire will. Just one example of the lightest tire performing the worst in a test would be in a recent test is a test of extreme performance summer tires, which many use for autocross. In this test the lightest tire, the Kumho ECSTA XS, came in dead last, while the heavier Bridgestone RE11 and Yokohama AD08 were better. (link to test http://www.tirerack.com/tires/tests/...iate=FH8<br />. )

Keep in mind that while wheel weight can be an important factor to consider, tire weight should actually be one of the last things to consider when making a tire purchase decision. Dry grip, wet grip, and steering response are more far important factors for an enthusiast trying to maximize performance.

I am shopping for a light setup fro street use.

I have come up with the Apex EC-7 18" with square wheels (18-21lbs Forged) and the 245/40/18 Pirelli PZero Nero All Season as RFT replacments. Still reasearching the best combination wheel/tire widths fo rthe best looking fit I can use all year. The wheels did not release pricing yet but, thinking about 300 per wheel and $700 for 245/40 tires.

45lbs 18" $1200+700= Now that is equvalent to a 17" custom gravity forged wheel and tire in an 18" stance
41lbs 17" $1100+600=


I actually got the 18VMR Staggered and the Hankok evo 110. Hated them, felt like the brakes were stressed and was not confident on the high speed cornering.

52lbs

Thats a 7lb unsprung difference per wheel

Plus the better fuel economy and less wear

Also came a cross a dunlop kevlar that is 20% lighter. probable about 20lbs

A 35lb setup would be ideal all around. IMHO...Any feedback on these gary?

Last edited by VaDuro; 05-09-2012 at 10:04 PM.
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