Lightweight Wheels Effect

[GRUMPY-S4]

Ive been reading on the effect on handling and acceleration that lightweight wheels have due to the impact unsprung weight causes. What is the weight of the OEM "Flower" wheels? Like 29#??? Is shedding 9# on each corner that noticeable in handling and to the "Butt Dyno"?


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[MrFunk]

Shedding 9lbs per corner of rotational weight would be very noticeable. Even more-so if reducing the wheel diameter while at it.
OEM wheels weigh close to 50lbs (with tires) if I'm not mistaken.

[GRUMPY-S4]

Well I am keeping the stock tires (Conti's). Once those wear I will be going with PSS's and that will shed even more weight.


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[SteveYem]

Lighter weight wheel + tire assembly, especially 9 lbs less, will be noticeable both in acceleration and in braking. In fact you may even notice better response from your shocks insofar as quick rebound due to the shocks having to push less weight.

As MrFunk mentioned, a decrease in diameter as well as weight would be an even bigger help. The resistance to roll is inertia, which is a measure of the distribution of the wheel's mass relative to its rotational axis.

[somedude]

lighter wheels and tires make everything better. A 9lb reduction will not go unnoticed

[onlyaudis]

On modern car like ours, the suspension was actually designed for a heavier tire wheel combo, so its not as bad as putting heavy +3 wheels and tires on some early 90's car. That said, there are a lot of tests posted online that show a very minor acceleration improvement in dramatically lowering wheel weight. In my experience, the effect I noticed the most was shock response being better, and the car feeling overall more responsive to inputs. Makes sense, as a heavier tire wheel in motion will not be as responsive to change as a lighter one.


https://www.google.com/webhp?sourcei...eration+tested

[phanker]

Noticeable for me shaving off 8lbs or so per corner. Feels like it's much more responsive with acceleration / braking. Car doesn't feel as heavy essentially. Shocks are tad more choppy and firmer feeling which I love as it's too comfy with stock wheels. Steering response is better but it does feel lighter which is a downside since it's too light already in Dynamic mode. It would have been perfect with the old Dynamic mode before the recent steering patch Audi did.

[kap09]

For me it was most noticeable under braking, but improvements were noticed all around.

[mact3333]

There was a huge difference on how the car felt accelerating, braking and cornering when I lost 5 lbs per corner on wheels, 5 on tires, and maybe 10 on BBK...you lose 20 lbs per corner and it feels like you lost 300 lbs in unsprung weight...make scar feel like it weighs 3600 lbs....car doesnt feel heavy anymore.

[BoostEasy]

Brake rotors have a fairly small diameter so they won't contribute a lot to rotational inertia. Generally speaking there are formulas and proofs done on the net you can look up that put a typical brake rotor inertia savings benefit of about 1.2x actual weight savings. So if you saved 5lbs per rotor it's like taking 6lbs out of the car for acceleration/braking.

Wheels are a little more complex because diameters can vary a bit and weight can come from the tire and different places on the rim. Given the diameter is much larger vs a brake rotor, the gain should be more for rotational inertia but I don't have the "inertia to dead weight" conversion number handy. It's probably somewhere 1.6-2.0 I'd guess.

I'd think it'd be noticeable if you got much lighter wheels, esp for suspension response as others stated.

[eurotic]

I wold love to see an instrumented test conducted during some other blind test where wheels are swapped several times without the driver knowing what is on the car and when. And have them document what they feel then compare to what was on the car and what the instruments say. I am not doubting that there is a difference but I know from my experience with getting a heavier tire (+4 lbs each which I figure is huge especially as the weight is so far out) installed I didn't feel anything that was significant. That said I wasn't out to conduct a test I just figured it would feel like driving a dump truck by what people say here. I figure I am just not that in tune with the car as others may be.