Noticeable Difference with Lighter Wheels?

[LatentWagen]

Went from the massively heavy '08 spec B stockers to feather-weight 17" SSR Comps. Between wheels and tires, I lost approximately 17lbs per corner, over 65lbs total. I can feel the difference in acceleration between a full and mostly empty gas tank, and the wheel change was nearly equivalent in weight reduction, but it was all unsprung rotational mass. The difference was immediately noticable, from the first throttle application.

[BoozeRS05]

Went from the massively heavy '08 spec B stockers to feather-weight 17" SSR Comps. Between wheels and tires, I lost approximately 17lbs per corner, over 65lbs total. I can feel the difference in acceleration between a full and mostly empty gas tank, and the wheel change was nearly equivalent in weight reduction, but it was all unsprung rotational mass. The difference was immediately noticable, from the first throttle application.

 

 

Its because your 18" tire has an overall larger diameter compared to the 17" tire. You are def gonna feel that effect on the gearing. Its not the weight difference you are feeling.

 

Edited the quote for your application, but it's the diameter your noticing based on whitetiger's expertise. My summer and winter setup are dramatically different in weight, but the difference I'm told is felt in the diameter of the setups, ie 18" summer wheel compared to 17" winter wheel..

[whitetiger]

Its not the diameter of the rim, but the diameter of the overall tire/rim assembly. you can have a taller 17" wheel/tire setup and a shorter 18" wheel/tire setup. we dont know what his tire sizing was on the 2 different rims, but generally the spec b runs a taller setup compared to LGT sizing. so if he ran LGT sizes on the 17" and compares them to spec b sizing on the 18" then of course the 17" setup will feel faster regardless of weight.

[whitetiger]

the stock spec b (215/45/18) overall diameter is 25.618" while the stock lgt overall diameter (215/45/17) is 24.618. that's a huge difference in acceleration gearing advantage for the LGT, wheel wise. Even if he ran (225/45/17) with an overall daimeter of 24.972", the stock spec b combo is over .5" taller and that will still be a noticeable difference in acceleration, regardless of wheel weight.

[Sideways the Seven]

This seems like a good place to ask this question; Considering all other things equal, including tire brand and model, which would be better in a ride and handling tradeoff; a 225/45/18 which is closer to the stock diameter of 225/55/17, or 245/40/18 which has a larger contact patch and a shorter, and theoretically stiffer, sidewall. Either choice is <3% difference from the stock diameter setup. Are there more factors I should be considering?

[whitetiger]

225/45/18 and 245/40/18 have nearly identical side walls and overall diameters(only 1/4" overall diameter difference) remember the middle number in the tire measurement is a percentage, not a direct measurement. so for a 225/45/18, the side wall is 45% of 225mm for an 18" rim.

 

based on this, id expect either 18" tire you have here to ride the same, so id get the wider one.

[Sideways the Seven]

That's what I was thinking. Thanks!

[LatentWagen]

the stock spec b (215/45/18) overall diameter is 25.618" while the stock lgt overall diameter (215/45/17) is 24.618. that's a huge difference in acceleration gearing advantage for the LGT, wheel wise. Even if he ran (225/45/17) with an overall daimeter of 24.972", the stock spec b combo is over .5" taller and that will still be a noticeable difference in acceleration, regardless of wheel weight.

 

Yup, I went from the stock 215/45/18 to a 225/45/17... the half inch difference in tire height works out to slightly more than 2%, a pretty paltry gearing advantage. I won't argue that it is there, and it makes a difference... but the difference that I felt is due in most part to weight reduction, not gearing. 65lbs of rotating mass is huge. When I put on the winter tires (215/50/17), I'll get back to you!

 

To clarify, if you re-read my original post, I never mentioned acceleration. The most noticeable (for me) changes were the initial throttle application (mostly taking off from a stop, low RPM), and the response/compliance of the suspension and wheels over bumps.

[Drift Motion]

its funny how much you guys care about the weight difference so much while driving on the street...

 

I'm no race car driver, but all my friends and I who joins the local track day events/competes cares more about the strength/price of the wheel more than the weight of the wheel...

[Sideways the Seven]

I'll have the 245/40/18 mounted tomorrow. I'm not expecting anything noticeable from what I have now, but we'll see.

 

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[LatentWagen]

its funny how much you guys care about the weight difference so much while driving on the street...

 

I'm no race car driver, but all my friends and I who joins the local track day events/competes cares more about the strength/price of the wheel more than the weight of the wheel...

 

I think it's funny that someone would come into a thread about wheel weight and find it funny that all we seem to care about is wheel weight

 

Lightness, strength/durability, and looks are all key features of a nice set of wheels. But price is not a feature, price is a compromise... you do the best you can for your goals and price point, but everything is relative.

 

I may not compete at local track days, like your friends, but I see the value in proper wheels that happen to be light, especially on the street. I have bent OEM wheels, Rotas, Enkeis, and cast BBS on NYC potholes that the SSRs shrug off, and they're only quasi-forged

[stalintc]

its funny how much you guys care about the weight difference so much while driving on the street...

 

I'm no race car driver, but all my friends and I who joins the local track day events/competes cares more about the strength/price of the wheel more than the weight of the wheel...

 

I am pretty freakin far from a race car driver myself, I am just trying to understand a bit more about wheel choices and their respective benefits. This is why I asked the question, not posited the statement about weight.

 

So weight is easy to boil down to a single number, and that data is readily available. How does one measure the strength of a wheel? I assume production process plays a large role in this, but is there more data that is available? I know that material, hardness, forming process, quality of process, etc all play a major role in this. I am not a "smithy per se, or otherwise trained in the metallurgical arts" but I have a pretty good understanding about what it takes to make a good knife blade, and that is peanuts compared to a wheel.

 

Thanks,

[Drift Motion]

usually a heavier wheel, given the same manufacturing process/style and not taking amount of pin hole and air bubble into consideration, will be stronger

 

so all of you complaining about cracking the wheel, get something heavy, I can almost guarantee you that it will be a lot stronger. RPF1 are good wheels, good qc, good manufacturing process (flow form cast) but everyone knows that they crack so easily...

[soloz2]

Going from stock wheels with 205 50 17 conti ewc to lightweight kosei k1 ts wrapped in 225 40 18 stsrspecs handling changed, but that's mostly due to the tire. My car might feel faster if the tires were the same width idk.

 

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[LatentWagen]

so all of you complaining about cracking the wheel, get something heavy, I can almost guarantee you that it will be a lot stronger.

 

I see what you're getting at, but I don't think you're understanding the relationships correctly.

 

Wheel design & construction has as much impact on strength, if not more, than the weight of the material. A multi-spoke, heavy OEM cast wheel is heavy because it's cheaper to cast more material than it is to forge less. They must use the extra material to achieve the strength they want, within the confines of budget and manufacturing, of course.

 

When you design the structure of the wheel properly, using the right alloy, form it in the strongest process, "lightness" is a happy byproduct. You don't need as much metal if you do it right

[iNVAR]

I'm fairly certain Drift Motion knows about wheel construction and the relationship between weight, strength, materials and manufacturing process.

 

usually a heavier wheel, given the same manufacturing process/style and not taking amount of pin hole and air bubble into consideration, will be stronger

I think that sort of implies what you said.

[LatentWagen]

Didn't mean to impugn Drift Motion's wisdom, iNVAR. Since you're speaking up, maybe you could shed some light on why he would tell people to get heavy wheels because they are stronger. Because to my sensibilities, that doesn't really jive. I'd like to hear more.

 

My opinion, here: a heavy wheel does not a strong wheel make. A good design, however, does make it strong. Materials and processes discussion aside. It could be forged, cast, or popsicle sticks.

[BoozeRS05]

DM is pretty bias when it comes to wheels, from my experience. I'll take my medicine from whitetiger.

 

And I'll add this. Of all the wheels I've owned (8 different sets), my Rota wheels have been the strongest of them all (includes- Enkei, OZ racing, OEM and Rota). I've damaged every setup listed there, but never a set of Rotas. It makes me feel a little better knowing my heavy wheels aren't a big deal, and my tires are where I'm feeling the biggest difference (aside from my wallet ).

[iNVAR]

Didn't mean to impugn Drift Motion's wisdom, iNVAR. Since you're speaking up, maybe you could shed some light on why he would tell people to get heavy wheels because they are stronger. Because to my sensibilities, that doesn't really jive. I'd like to hear more.

I don't believe that's what he's saying at all. Read his post again:

 

usually a heavier wheel, given the same manufacturing process/style and not taking amount of pin hole and air bubble into consideration, will be stronger

 

so all of you complaining about cracking the wheel, get something heavy, I can almost guarantee you that it will be a lot stronger. RPF1 are good wheels, good qc, good manufacturing process (flow form cast) but everyone knows that they crack so easily...

He cited RPF1 specifically as an example, which are ultra lightweight for non-forged wheels. They crack and dent easily because of how light they are. Given what he said in his first sentence, if you took an RPF1 and made it a lot heavier, they would be much stronger. They are also cheap.

 

DM's pretty much playing the odds, as I highlighted with the bolds/underlines.

 

Most people try to get wheels that are lightweight and cheap. This means that their wheel will likely dent/crack. To those people, he's told them to get something heavier. If budget/price is a fixed variable by that person (who likely cheaped out in the first place, which led to their rims denting/cracking), then in order to increase strength, weight would have to be increased as well.

 

Unless of course you throw design into the mix, which would be another variable. But that almost goes hand in hand with price too.

 

Cheap + strong + lightweight don't mix, and most people are on a budget.

 

Cheap heavy wheels aren't necessarily strong, as evidenced by many crappy aftermarket wheels, but it's stronger than a just-as-cheap lightweight wheel. I think that's all he was really saying.

[LatentWagen]

You said it yourself... you think that the RPF-1 (your example) is prone to cracking "because of how light they are" and I think it's more a question of design than weight. By your logic, all light wheels will be prone to failure. I'm of the opinion that your logic is flawed. We can agree to disagree on this one

[iNVAR]

Sorry, I can't let it go at that because that's simply not what I said.

 

The RPF1 cracks because it's a combination of being lightweight and cheap. If you can find me another wheel at that price point AND weight that is stronger, I'd be interested. That's really my only point, and I think what DM was trying to get at.

 

People complain about wheels cracking because they want it to be lightweight and cheap and strong and that's simply not going to happen.

 

Strong + lightweight = pricey

Strong + cheap = heavy

Cheap + lightweight = weak

 

Take an RPF1, make it heavier, and you'll have a stronger RPF1 at just about the same cost.

 

My Volk CE28 weighed 14.5 lbs for a 18x7.5 which is very lightweight, and they're certainly not cheap. If it had more material on it, it might have survived the pothole without damage... maybe. Can't say for sure. How strong was it though? I don't know. Maybe it was already as strong as my stock wheels despite being so much lighter. Maybe they shed a little too much weight and made it a bit weaker.

[LatentWagen]

Sorry, I can't let it go at that because that's simply not what I said.

 

...

 

Take an RPF1, make it heavier, and you'll have a stronger RPF1 at just about the same cost.

 

I know why you're winking.

 

Psst... adding weight to a wheel doesn't make it stronger.

[Sideways the Seven]

This conversation certainly got interesting.

 

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[iNVAR]

I know why you're winking.

 

Psst... adding weight to a wheel doesn't make it stronger.

Yes, it does, all other things being equal. Stop trying to purposely misconstrue what I've said. You know I'm not talking about strapping a piece of dead weight to a wheel and saying it'll be stronger.

 

If you have an RPF1 designed for 15.5 lbs, and then you tell them, "Hey, you have 4 more lbs of material to work with, we can deal with a 19.5 lb rim" then it will be stronger.

 

You said price is a compromise, and it absolutely is. So is weight, all other things being equal.

 

You can build a stronger wheel with 19.5 lbs to work with compared to 15.5 lbs of an RPF1 if you manufacture it the same way, period.

[LatentWagen]

Yes, it does, all other things being equal. Stop trying to purposely misconstrue what I've said. You know I'm not talking about strapping a piece of dead weight to a wheel and saying it'll be stronger.

 

If you have an RPF1 designed for 15.5 lbs, and then you tell them, "Hey, you have 4 more lbs of material to work with, we can deal with a 19.5 lb rim" then it will be stronger.

 

You said price is a compromise, and it absolutely is. So is weight, all other things being equal.

 

You can build a stronger wheel with 19.5 lbs to work with compared to 15.5 lbs of an RPF1 if you manufacture it the same way, period.

 

Nobody is trying to twist your words, or ruffle your feathers. I think we are about to have a breakthrough.

 

Let's brainstorm for a minute... Using your example again, how would you add that 4lbs of weight to your RPF-1? Where would you add material? How would you keep all other things equal? This is hard to do in the real world.

 

So now we're talking about altering the design of the wheel... and that's what I've been saying from the start: wheel strength is more a function of design than weight.

 

Just because a cheap wheel is weak, doesn't mean it's necessarily weak because it's light (could be weak because it's cheap, or poorly designed). Causation and correlation... there is a difference. There are plenty of heavy weak wheels too. Just ask the guy who bends expensive OEM wheels but not cheap Rotas that weigh less.