LIGHTWEIGHT Wheels

[Chris Leger]

You came to the Lightweight Wheels thread to write "why care about weight?" Recheck your math.

They're et45. At least that's what I ordered. I haven't measured them.

They look great but unless you're autocrossing etc, why care about weight? They potentially track better but because of that, will also ride correspondingly worse due to more wheel movement (better tracking) and less tire deflection. Are those the 35 offset? They look it (good).

 

[bnperrone]

They look great but unless you're autocrossing etc, why care about weight? They potentially track better but because of that, will also ride correspondingly worse due to more wheel movement (better tracking) and less tire deflection. Are those the 35 offset? They look it (good).

I’ve had Neuspeed RS wheels on 2 different VWs and covered about 150k miles on them. I can assure you there is a noticeable improvement to losing 10lbs of unsprung, rotational mass at each corner. No track time or anything, just nimbler feel and the ride absolutely is smoother as a daily driver, presumably because the suspension doesn’t have to work as hard to control the forces. We’ve got some bad roads where I am and I have yet to bend or damage one, either.

 

[khail19]

I’ve had Neuspeed RS wheels on 2 different VWs and covered about 150k miles on them. I can assure you there is a noticeable improvement to losing 10lbs of unsprung, rotational mass at each corner. No track time or anything, just nimbler feel and the ride absolutely is smoother as a daily driver, presumably because the suspension doesn’t have to work as hard to control the forces. We’ve got some bad roads where I am and I have yet to bend or damage one, either.

Same here, lighter wheels have always rode better on my all vehicles. Not just VWs, I'm talking Subarus, Nissans, etc. back to the late 90s.

 

[goodvibes]

Trade offs are normal. Lighter wheels respond more easily to road imperfections which is why they're good for tracking but that's added deflection to follow imperfections instead of the tire deforming due to the increased inertia of added mass taking the edge off of suspension impact. Of course tire pressure and other variables are in play but the physics is sound. I'm not here to argue but here for an extended argument but here's a controlled test of plusses and minuses of lighter wheels.
https://www.tirerack.com/upgrade-garage/do-lightweight-wheels-affect-performance
Of course this will also be frequency and amplitude dependent so can vary by system (combo).
Not a big deal and they looks great. Just some info pointing out that impact harshness is not the absolute reason to investigate lighter wheels. Enjoy them.

 

[bnperrone]

That article doesn’t really support what you’re saying. In the real world as well as in the performance testing they praised the lighter setup. The increase in impact harshness they mention included 2 critical variables: moving from grand touring to max performance tires, and also going to a plus-1 size configuration. That’s your impact harshness.

The point about the plus-sized anchors having dampening benefits doesn’t outweigh the significant cons, and the lightweight setup was clearly stated as being superior. Any discussion about the benefits of heavier wheels is purely academic. Even resistance to bending and breaking is not universally better for heavier wheels. There are light and strong wheels, heavy and weak wheels, and everything in between.

 

[victorofhavoc]

That article doesn’t really support what you’re saying. In the real world as well as in the performance testing they praised the lighter setup. The increase in impact harshness they mention included 2 critical variables: moving from grand touring to max performance tires, and also going to a plus-1 size configuration. That’s your impact harshness.

The point about the plus-sized anchors having dampening benefits doesn’t outweigh the significant cons, and the lightweight setup was clearly stated as being superior. Any discussion about the benefits of heavier wheels is purely academic. Even resistance to bending and breaking is not universally better for heavier wheels. There are light and strong wheels, heavy and weak wheels, and everything in between.

Agreed with thus.

I'll add that tire is tremendously more important than wheel weight. Wheel strength can also "outweigh" wheel weight in terms of performance but differences start to become minute and only noticeable by advanced to elite drivers. Enkei had a few articles and tests about this topic, testing on identical sizes and tires.

As a fun anecdotal comparison, my wife's car has a 20" wheel with a 255/50 blizzak and a 22" wheel with a 275/40 ps4s. The 22 setup is 14lbs/corner lighter so differences are fairly extreme. The 22s are tremendously less crashy, much smoother over large impacts, handle way better, accelerate tremendously better, and brake way better. The trade off is only on small rapid impacts where the stiff sidewall of the ps4s transmits a lot of that high frequency/sharp impact feel.

 

[goodvibes]

Agreed with thus.

I'll add that tire is tremendously more important than wheel weight. Wheel strength can also "outweigh" wheel weight in terms of performance but differences start to become minute and only noticeable by advanced to elite drivers. Enkei had a few articles and tests about this topic, testing on identical sizes and tires.

As a fun anecdotal comparison, my wife's car has a 20" wheel with a 255/50 blizzak and a 22" wheel with a 275/40 ps4s. The 22 setup is 14lbs/corner lighter so differences are fairly extreme. The 22s are tremendously less crashy, much smoother over large

Any acceleration increase (which is valid and subtle) will be related to overall mass savings as opposed rotational mass. I have nothing against lighter wheels. Just know why your getting them and the physics involved. Lighter wheels track better and save weight, They don't ride better unless there's some specific frequency of modulation benefit.. It's no different than how flywheel weight affects acceleration. They track better buy following disturbances better with less inertia and allow the suspension to deal with them. The more energy the suspension sees, the more that gets through to the chassis. If you get a situation where the frequency lines up really well it could conceivably ride netter but it would be an exception.

 

[Chris Leger]

Any acceleration increase (which is valid and subtle) will be related to overall mass savings as opposed rotational mass. I have nothing against lighter wheels. Just know why your getting them and the physics involved. Lighter wheels track better and save weight, They don't ride better unless there's some specific frequency of modulation benefit.. It's no different than how flywheel weight affects acceleration. They track better buy following disturbances better with less inertia and allow the suspension to deal with them. The more energy the suspension sees, the more that gets through to the chassis. If you get a situation where the frequency lines up really well it could conceivably ride netter but it would be an exception.

Try this on ChatGPT. I used my own car & parameters. Substitute yours, if you like.

For a 2015 Volkswagen Golf S 2-door, what is the suspension frequency based on known spring rates and vehicle weight?
- then -
For this car, calculate and compare the ride harshness with a 225/45-R17 tire & wheel combination weighing 40 and 47 lbs, respectively.
- then -
Is there a point at which the heavier wheel will ride better than the lighter as amplitude decreases? If so, what is that point?

I got:

 

[scrllock]

once again, it's simpler to just block people posting chatgpt garbage, since it shows they don't have the knowledge or time to understand the topic properly.

 

[Chris Leger]

once again, it's simpler to just block people posting chatgpt garbage, since it shows they don't have the knowledge or time to understand the topic properly.

Why don't you explain it to me then, and share your understanding?

 

[victorofhavoc]

I'm not sure what the point of the chatgpt is...? I hope you're also aware that chatgpt gets its data from real research and internet forum shenanigans all the same. While it can be a useful tool, it does not use logic and reason like a human.

Lighter wheels and flywheels can change speed more easily, and this works for acceleration and deceleration. It's not just about acceleration, it's about the change in acceleration as well (known as jerk).

This impacts both vertical movement of the wheel, turning of the wheel for steering (gyro effect), and rotation of the wheel (which is impacted by friction mu of tire, brakes, tire weight, sidewall flex, pressure). It also impacts the force transmitted to bushings and their resultant flex, to a small degree. This ALSO makes them easier to act on/against.

I have no idea what points are even being argued anymore . The above are just helpful facts .

 

[Chris Leger]

I'm not sure what the point of the chatgpt is...? I hope you're also aware that chatgpt gets its data from real research and internet forum shenanigans all the same. While it can be a useful tool, it does not use logic and reason like a human.

Lighter wheels and flywheels can change speed more easily, and this works for acceleration and deceleration. It's not just about acceleration, it's about the change in acceleration as well (known as jerk).

This impacts both vertical movement of the wheel, turning of the wheel for steering (gyro effect), and rotation of the wheel (which is impacted by friction mu of tire, brakes, tire weight, sidewall flex, pressure). It also impacts the force transmitted to bushings and their resultant flex, to a small degree. This ALSO makes them easier to act on/against.

I have no idea what points are even being argued anymore . The above are just helpful facts .

I have some modest understanding of how ChatGPT works.

The point of resorting to ChatGPT was to test the repeated claim that lighter wheels somehow "ride correspondingly worse" than heavier ones. My intuition told me that this is likely true under some circumstances. If you follow the steps I outlined above, (or take any approach at it that you like,) you'll see that ChatGPT spews loads of calculus that it probably does not derive from forums like this one.

It turns out that (according to ChatGPT) the claim that lighter wheels "ride correspondingly worse" is in fact true, but only under the very narrowest and practically insignificant circumstances, i.e. for bumps with amplitude of between 0.5 and 1mm, that come at a frequency greater than the suspension's natural frequency, ~1.5x/sec.

Now, if you know otherwise, I'd love to learn. I am not an ME or Colin Chapman.

 

[khail19]

I think everyone here is in agreement except for goodvibes?

Real world, lighter wheels = better ride.

That's always been my experience, and I've had a lot of different wheels on a lot of different vehicles.

 

[bnperrone]

I think everyone here is in agreement except for goodvibes?

Real world, lighter wheels = better ride.

That's always been my experience, and I've had a lot of different wheels on a lot of different vehicles.

Correct on all.

Reduction of rotational and unsprung mass both deliver improvements in the real world. Most of us have experienced it firsthand. The tradeoffs to be managed are cost and durability, and that’s where everybody needs to decide what’s best for them.

 

[victorofhavoc]

I think everyone here is in agreement except for goodvibes?

Real world, lighter wheels = better ride.

That's always been my experience, and I've had a lot of different wheels on a lot of different vehicles.

For the most part, yes.

I do think the chatgpt output points out that it hasn't been in my head for why "sharp small impacts" are more noticeable.

The two areas around me where I feel a more massive wheel helps are the chipsealed roads where we go at low speeds and the metal expansion joists where the dip is an inch, but at high speed the wheel won't dip that far.

Other than that, I think lighter helps all the way down until you start sacrificing strength. Enkei did a test on this many years ago and saw a car go measurably faster with a stronger but heavier (2lbs) wheel. Granted they have a leg in the race, but it's reasonable, especially when you consider the benefit of carbon wheels beyond the light weight.