TrevMo

Does anyone know what the specs are on the OEM SS/TC wheels?

I know they are 18" and 7.5" width...I believe the lug pattern is 5 x 110...

Anyone know what the offset is? I've read that sometimes offset is stamped on the wheels, but I have not made an effort to look for this.

rocco11189

I think they are either 38 or 40 offset

DC52NV

moved to the wheels section. please post in correct section.

SS/SC Crazer

what is the wheel weight, the 07 rims are 24lbs, if these are lighter i might get them for my 07.

SS/SC Crazer

does anybody know the wheel weight for the 2008 cobalt sswheels???????

rocketpunch1221

No. I've been trying to get that info and I got nothing.

SilverSS/SC

Te offset is 42 mm . A member weighed theirs @ 23 lbs a wheel without a tire mounted .

rocketpunch1221

THANKS!!!!!!!!!

23lbs...ouch

SportredSS

Contrary to what people think, even if our wheels were 13 lbs each... the car will not accelerate any faster... I've tried 50% lighter wheels on many different cars and it makes no sense to lighten the wheels\unsprung weight unless you want better ( for the track) cornering... that's it....Wont do any good for mostly street drivers...

DieselHybrid

SportredSS-

Physics begs to differ. Our good friend Newton derived ∑F = m dV/dT, or ∑F = m a, therefore a=∑F/m. Acceleration is directly proportional to net force and inversely proportional to mass.

Rotational acceleration is directly proportional to the net torque and inversely proportional to the moment of inertia, ∑τ = I α. Where I = ∑ ri^2 mi = ⌠⌡ r^2 dm.

Therefore, reducing mass results in an improved acceleration. While reducing rotational mass not only reduces the amount of mass in translation motion but also reduces the moment of inertia. A double whammy! (Notice it is far more important to reduce mass the further away from the center of rotation than from the center itself- this varies as the square of the distance (radius).) The diameter and mass (moment of inertia) of the part determines its effect on the engine- for example, lowering the weight of an 18-inch wheel will have a much more pronounced effect than lowering the weight of a 2.5-inch driveshaft.

Now, it is possible that you may not have "felt" a difference because the "lighter" wheels you used may have had less mass near the center of the hub- and not at the rim perimeter- than the original wheels you were comparing them to. Without a repeatable test- it is hard to determine why you didn't "feel" a difference.

In summary, any mass you can trim from rotating parts will not only help reduce your total vehicle weight, but will also help your rotating parts rev more freely, making them accelerate-or decelerate-faster- making your vehicle quicker, and more fuel efficient.

Isn't physics fun?

rocketpunch1221

Base on Newton's 2nd law of rotation, mathematically a lighter wheel with the same diameter will speed up faster than a heavier one. Whether the test you did was well controlled enough to reflect that, that would be a different issue.

More importantly it is not the weight of the wheel itself, but rather the moment of inertia of the wheel that will have a greater impact on the angular acceleration. That is exactly why you will see ultra high end wheels like Dymag utilizing carbon fiber for the rim; all because of the advantages in lowering the moment of inertia. Conversely, a lighter wheel will also improve braking performance due to the reduced energy required to keep the wheel from rotating.

However, the real advantage of using a lighter wheel is to improve the suspension efficiency for a more compliant tire contact. It is also critical in racing application as the sprung weight is reduced, the unsprung weight will also have to reduced to maintained the targeted sprung-to-unsprung ratio.

DieselHybrid

Well said, rocketpunch1221!

Back on topic- I am surprised Chevy's "forged" Cobalt SS 18-inch wheel weighs a whopping a 23lbs! Yeeeouch! That weight is more in line with a cast aluminum wheel. Are they really forged?

So- out of curiosity, what is the lightest & strongest (read: forged) wheel available for the Cobalt SS (5x110, 40mm offset)? Who sells them and how much?

18-inch would be nice, however I am willing to go down to a 17-inch wheel to further reduce weight.

Thanks in advance!

rocketpunch1221

Well, as you know "forge" is only the process, if the material they are using is not light, the end result won't be light either.

I am hunting a set for the track next year myself. ATM, The best wheel I can find that will fit the LNF SS without spacers is OZ's Ultraleggera 18x8 [18.5lb] at $350 a pop: http://www.tirerack.com/wheels/Wheel...All&sort=Brand

In terms of light weight forged wheel, the sky is the limit. If you are willing to pay I am sure you can find one...lol

ericgt79

iTrader: (7)

those wheels dont fit...the wheel clears the brembo and all that but the center caps dotn work, welcome to 5x110

D4u2s0t

huh?

SUKXOST

My stocker 05 SS rims were said to be 26lbs. I guess with the 5 spoke rims of my 05 SC basically having the middle of the spoke cut out like on my 09 TC...I guess that's 3 lbs.

True, lighter weight will spin faster and easier. Exaggerate it...put a 500lb rim on there and try to drive and then put even the same size wheel but it weighs 1lb.......common sense says it will spin easier. All that scientific mumbo jumbo makes my head hurt. :P

rallyracer

How do you know?

rocketpunch1221

Those will be my track wheels, couldn't careless about the center cap, at least for my application.

As long as I can mount them on, clears everything and can torque the nuts tight to specification; I will consider it fits.

rallyracer

Yeah some road racing even here require you to remove your center caps anyways...

ericgt79

iTrader: (7)

when the wheels first came out someone from this forum i believe it was rissa did a test fit with some vendor and they found the center caps didnt work then a few weeks later after i forgot i tried to order them from gravana and they canceled the order for me and told me they dont fit the center caps

rocketpunch1221

Just wanted to make this clear. When you said "center cap" do mean the hub?? Cause to me "center cap" is the cap that goes on to the center of the wheel.

Tire rack just added that wheel recently under the 08/09 Cobalt SS.

Rissa

Yes the hub, the wheels wouldn't work with the ones they had originally but I heard they got a new cap for them.

rocketpunch1221

Glad to hear that, so the wheel will actually be hub centric out of the box. It is an easy fix if the hub is smaller by using a hub ring, but not the other way around.

Speaking from experience, just make sure you get the metal ones if you ever have to use one.

06CobaltssOrange

rule of thumb 1 lb taken off any rotating mass takes 11lbs of a vehicle

tdipowered

um yea lighter wheels mos def help....why would they make lightened flywheels? physics is your friend. dont dis on physics.