Does wheel weight matter THAT much?

[DrJuice164]

Just wondering how much rim weight plays into preformace of a car. I personaly have only driven cars with low horsepower and heavy whees (24lbs each) and those made a noticable difference. But to those with higher horsepower cars, are the weight of the wheel negated by the power the engine makes?

[sensibleS13driver]

All of these articles are very helpful to what you're wondering, hope they help http://forum.miata.net/vb/showthread.php?t=40082

[Looneybomber]

On motorcycles it helps out. I couldn't imagine running a pair of CF Marchesini's. The front wheel is around 3lbs.

*EDIT* I just read this post again. I meant to say Dymag's, not Marchesini...They make good magnesium wheels, but Dymag makes the good CF wheels.
Modified by Looneybomber at 9:25 PM 3/13/2006

[DrJuice164]

Very nice find sensibleS13driver, thanks for the info

[InsanityInc]

Would you add weight to your flywheel? Then why add weight to your wheels?

[Looneybomber]

Would you add weight to your flywheel? Then why add weight to your wheels?

Rock crawlers use heavy flywheels, but that's a totally different story.

[sensibleS13driver]

haha yea you know miata guys have to find all the power they can, theyre also big into technicalities

[audtatious]

For every 100 pounds of unsprung weight that is removed, you fee up hp. This could equal as much as -.1 et times. Of course, lowering rim weight and increasing diameter is kind of a push due to additional rotating mass.

At least, that is what I have seen "out there on the web".

[Red coupe]

its not just a hp thing, less unsprung weight makes it easier for the suspension to do its job, and the wheel to follow the road...

[InsanityInc]

Rock crawlers use heavy flywheels, but that's a totally different story.

Alright, so if you want to build a rock-crawling 240, go for it. Otherwise....

[InsanityInc]

For every 100 pounds of unsprung weight that is removed, you fee up hp. This could equal as much as -.1 et times. Of course, lowering rim weight and increasing diameter is kind of a push due to additional rotating mass.

At least, that is what I have seen "out there on the web".

That's really, really, REALLY wrong.

Unsprung weight is the weight of your suspension and all things not suspended by the suspension (wheels, tires, etc). Lightening your control arms will obviously not gain you any power.

You gain power from lighter wheels because they are part of the drivetrain, so you are reducing drivetrain losses, same as a lightened flywheel or a lightened driveshaft.

Also, dropping 100lbs will gain you a LOT more than .1 in the 1/4. Hell, dropping 100lbs of sprung weight will likely gain you more than that.

[nismofly]

anybody know how much unsprung weight the 240 starts with? i bet its between like 200 and 250 if you think about it, and dropping half that is going to help a ton

and also like Red Coupe said its a lot more critical when youre turning

[Red coupe]

Next person to install springs/coilovers needs to brake out the bathroom scale to give us a rought estimate

[nismofly]

well its not just that

i figure most wheel / tire setups are around 160 lbs. and everything else is probably 50 - 75 lbs.

when im building my racecar ill probably do some research stuff like that

[audtatious]

That's really, really, REALLY wrong.

Unsprung weight is the weight of your suspension and all things not suspended by the suspension (wheels, tires, etc). Lightening your control arms will obviously not gain you any power.

You gain power from lighter wheels because they are part of the drivetrain, so you are reducing drivetrain losses, same as a lightened flywheel or a lightened driveshaft.

Also, dropping 100lbs will gain you a LOT more than .1 in the 1/4. Hell, dropping 100lbs of sprung weight will likely gain you more than that.

Unsprung weight is pretty much everything outboard of the struts/springs (the wheel/tire, brake rotor, caliper, hub and bearing, etc). You don't "gain" horsepower you free up what you already have available. Wheel/tire combinations that are lighter can impact 1/4-mile performance as there is less mass which requires less torque in comparison to the heavier wheel/tire combination.

[StatixNWH]

lol the sentra in one of those articles......they completely STRIPPED that thing, make it a convertable and took everything out....that only made them 2 seconds faster....so the question is, do you want style and performance, or just one of the 2

[crzycav86]

completely naked is sexy

[StatixNWH]

yeh but thats like a naked fat chick.....you only get one thing out of that....and its sick

[nismofly]

but its not a naked fat chick, a car with 4 subs and that sort of thing is a 500 lb. girl that thinks shes hot

i wouldnt go to the extent that they went, since you cant actually race a car in the condition they had it in

also it was running on absolutely horrible tires, theyd probably gain another second

however, id take a car with a stripped interior anyday over a car with stuff inside, "bling"

if you really care about performance enough you go all out

[crzycav86]

but anyway, lighter wheels are very important. first of all, the drive wheels will free up horsepower.

second, you get improved handling by reducing unsprung weight. That means your suspension will react more quickly to bumps, and it will increase grip.

wrong forum.. newb.

[McRussellPants]

The same people telling you wheel weight matters alot will be the same people running booty *** FN01s.

It won't make a huge difference. Handling differences will mainly be felt over bumps. Acceleration differences only in higher gears.

Don't worry about it and don't jerk yourself off telling other people your car handles better since you bought the 7in wide wheel instead of the 9 because its 1lb less.

[crzycav86]

Every surface has bumps and physics doesn't lie.

[S14KoukiMonster]

YES- it's proven even bigger rotors can lose significant power.It's simple physics- the bigger the diameter of a rotating mass, the more centrifugal force it has. That's what loses power.

Case Closed! :bonghit

[Zion8561]

well its not just that

i figure most wheel / tire setups are around 160 lbs. and everything else is probably 50 - 75 lbs.

when im building my racecar ill probably do some research stuff like that

I had the front suspension apart yesterday, the front steering knuckle with caliper and rotor probably weighed atleast 30 lbs each. Kinda surprised me when I pulled it off the ball joint

[hannibal]

one more point:Lighter is always better for performance. But unsprung weight has a bigger impact than sprung weight. So removing 20lbs from your wheels/tires/hubs/etc would yield better effects than removing 20lbs from your interior.

I think thats why peope make a big deal about wheel weight (and unsprung weight in general).

[skylndrftr]

does anyone have a good database of tire weigths? its not something that is gonna be at the top of the list when choosign tires...But at the same time they are on a much bigger radius than the wheel itself.

[gabossie]

wheelspecs.com has some wheel weights. There is another site that has a more comprehensive list of stock and aftermarket wheel weights but I can't remember what it is and it seems not to be in my bookmarks anymore

[Dori Dori]

I had the front suspension apart yesterday, the front steering knuckle with caliper and rotor probably weighed atleast 30 lbs each. Kinda surprised me when I pulled it off the ball joint

They are not that heavy, guarantee it.

[audtatious]

one more point:Lighter is always better for performance. But unsprung weight has a bigger impact than sprung weight. So removing 20lbs from your wheels/tires/hubs/etc would yield better effects than removing 20lbs from your interior.

I think thats why peope make a big deal about wheel weight (and unsprung weight in general).

From what I have seen, unsprung weight is worth 1.7-2x sprung weight. The only problem with all of this is you are talking minimal performance gains. When you are talking a 1/10th of a second decreases, it is hard to validate because of driver "error" or whatever. From a physics standpoint, it is sound.

[crzycav86]

They are not that heavy, guarantee it.

A caliper + rotor + spindle/hub is probably around 30 lbs.