Suppose I get very light rims and lighter than usual tires. My overall unsprung weight will reduce. I know that in terms of acceleration, MPG and maybe handling - I can see improvements (even if they are minor). What I'm trying to understand is if I also will acquire rough ride in terms of jitter or excessive vibrations of wheel assembly due to lower overall weight. As far as i know springs and shocks are made and calculated by Honda to match wheel weight and to give best results. If we change weight of wheels (heavier or lighter) spring will still stay same, so for example much heavier wheel will not be optimal choice, but much lighter wheel will also "throw off" under-sprung balance. I don't know how to explain it so it's clear, but for example with very light wheel if you hit pothole - it will jitter and reverberate more due to been lighter, rather than hitting the same pothole with stock (more heavier) wheel which will have enough mass to settle down quicker - as it was calculated by Honda initially. Am I wrong here? Thanks.

P.S. I'm not saying lighter wheels are not good, I'm just trying to understand how its "lightness" affects ride quality.

 

No lighter wheel won't create more "jitter" if anything it will reduce it.
Think about it like this wheel hits bump and bounces heavier wheel has more mass and will go farther/be harder for shock to slow down and when it does reach apex of its bounce there will be substantially more energy stored in the spring forcing it to hit road surface harder and faster, and again harder for shock to slow the wheel mass down.
GE8 suspension is very soft because chassis is so stiff I found that when it begins to wear out you get a lot of wheel hop and jitters over bumps. I was surprised to find when I went with stiffer progress springs and koni orange shocks that ride actually improved (in normal driving conditions) due to the suspension being able to absorb more and rebounding faster so on next bump it wasn't already bottomed out. Some bumps though it is more rough obviously but generally much better all around.

 

Thanks - it's good to know that.

 

Yes, lighter wheels should improve ride, dampers don't have to work as hard. Any change in ride for the worse most likely comes from the tires, not the wheels, if you got new or different tires.

 

I have wheels that are in combination of wheel and tire weighs like 7lbs less each then stock, the weight difference is very noticeable in a good way. On the highway i cant tell much but on city street stop and go is very noticeable. Canyon handling and handling on rough roads is better too .

 

I've been looking at these wheels (the lightest wheels I could find in the OEM size on tirerack.com) for a while now, I'm going to wait until after this winter though to make my move. In the meantime though, anyone know about the Kosei K4R wheels?

http://www.tirerack.com/wheels/Wheel...16&sort=Weight

 

I have the K4R on my fit for about a year and a half and I like the quality and price. So far no issues with bending or scratches. It had a very durable slick matte gray Teflon like finish.

 

I went with the 16x7.5 wheel though and 205 50 16 tires

 

Oh nice. Thanks for the pictures of that. Pardon my ignorance though, why did you choose for the extra inch that I would assume mean wider tires? Is it for better handling?

 

I chose the wider version because the 205 on a 7.5 wheel creates a slight tire stretch which improves steering response and reduces side wall deflection. You can run the same 205 on the 6.5 version they sell but it won't offer the same steering response and crispness the 7.5 will give you. . Plus I have the option to run 225 sometime down the road if I want.

 

Stock vs Kosei


Side view

 

Some lightweight wheels could have a lower load rating than OEM, which could affect durability. This is not really a concern for most applications but its something to be aware of.

 

Lowest rates wheel I've seen was 520kg and that a 5x100 wheel, most of not all 4x100 ones are rated for 690kg.

 

They come in 7.5? That's dreamy. Now I want those.

 

The ride will not change enough for you to notice; the spring rate (motion of the wheel/tires) is controlled by the shock and the weight of the tire/wheel is not a real control. MPG and acceleration will improve with lighter wheels and tires as you know but moreso with lighter tires, assuming the tires are good performance.
The torque required to turn the wheels/tires is twice as much for tire weight compared to wheels weight, or more.
Generally speakig litewheels matter ony on track.

 

Yep, mine are 16x7.5 +43 Fits perfectly no pun intended lol. Light and cheap, at $150 a piece for a Japanese made wheel its a bargain without going with cheap chinese reps.

 

Oh the K4R are made in Japan? I assumed that would have been one of the models that was offshored. That's a plus at $150 a wheel for sure.

 

No these are not offshore. At least not when I bought them, they were proudly stamped, labeled and casted made in Japan in the wheel. The K1 is offshore made in Thailand I think though.

 

I disagree with your blanket statements that account for only effect on wheel weight, you either have a miscalibrated but-dyno or have not had light wheel on the car.
Motion is controlled by springs shocks/struts yes, but what you are proposing is that a damper spring combo reacts the same with 30lb wheel/tire as it does with 40lb setup. Simply not reality, that's just physics, more mass = more energy. We are talking about bounce inertia hear not rotational mass.
On real roads at least in New England there is a noticeable difference in road feel especially on rough roads. Less unsprung weight is good and in general less weight is good.

The change in acceleration you mention is related to rotational mass and is just one aspect of the equation. You are correct about the tire weight being more significant, as it's the outermost part of the wheel/tire. Again though not whole story as the rotational mass furthest from the center is most significant, the outermost part of the wheel is important as well. Unfortunately most weight savings for lighter wheels is in the hub area

 

You are right.

But don't waste your time any more than that slim, pay no mind.