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Train wheels on steel have zero relevance to pneumatic tires on roads. Their compliance or non compliance has nothing to do with rolling resistance of steel on steel. You could easily make a compliant steel wheel but the compliance will have no impact at all on the rolling resistance.

Pneumatic tire compliance has a direct impact on all aspects of a tire's performance on different surfaces. Off-road tire's are large with low inflation pressures. Tire's for cars racing on very smooth surfaces are at the other extreme. Consumer vehicles are in between. They all need different compliance to fit intended use.

Rather than just making stuff up, a few minutes of reading about tires would save you from appearing ignorant. Read about pneumatic tires, not solid steel ones.
 

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Train wheels on steel have zero relevance to pneumatic tires on roads. Their compliance or non compliance has nothing to do with rolling resistance of steel on steel. You could easily make a compliant steel wheel but the compliance will have no impact at all on the rolling resistance.

Pneumatic tire compliance has a direct impact on all aspects of a tire's performance on different surfaces. Off-road tire's are large with low inflation pressures. Tire's for cars racing on very smooth surfaces are at the other extreme. Consumer vehicles are in between. They all need different compliance to fit intended use.

Rather than just making stuff up, a few minutes of reading about tires would save you from appearing ignorant. Read about pneumatic tires, not solid steel ones.
Frankly, I don't know what you are talking about. What is a compliant steel wheel? Is a compliant car tire just a soft tire?

Ask yourself do you disagree with this statement?

"underinflated tires with less stiff sidewalls have a higher rolling resistance than overinflated tires with stiffer side walls"

Rolling resistance is the energy required to move the wheel forward. It is determined by the energy absorbed by the tire and the road surface. Softer tire sidewalls (e.g. underinflated) and softer treads (e.g. snow tires), snow covered and gravel roads all absorb energy thus result in higher rolling resistance.
 

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Ask yourself do you disagree with this statement?

"underinflated tires with less stiff sidewalls have a higher rolling resistance than overinflated tires with stiffer side walls"
Wow! The straight answer to a stupid question is it depends. You apparently don't understand what tires do. They conform to imperfect road irregularities. To do this, they must deform. This causes heat which is wasted. Tires made for efficiency must be more supple as they will deform easier causing less waste heat. Tires built to handle well with narrow less compliant sidewalls are not as efficient when it comes to rolling resistance. Most road tires perform really badly off road with even more irregular surfaces and a huge increase in rolling resistance compared to purpose built tires. Those same off road tires have much higher rolling resistance than road tires on the road despite relatively supply sidewalls.

There are a ton of variables in how tires perform in various categories. Some you can isolate in a short discussion. But to say that train wheels are more efficient because they are less compliant is not only completely wrong, but does not apply at all when talking about tires.
 

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Wow! The straight answer to a stupid question is it depends. You apparently don't understand what tires do. They conform to imperfect road irregularities. To do this, they must deform. This causes heat which is wasted. Tires made for efficiency must be more supple as they will deform easier causing less waste heat. Tires built to handle well with narrow less compliant sidewalls are not as efficient when it comes to rolling resistance. Most road tires perform really badly off road with even more irregular surfaces and a huge increase in rolling resistance compared to purpose built tires. Those same off road tires have much higher rolling resistance than road tires on the road despite relatively supply sidewalls.

There are a ton of variables in how tires perform in various categories. Some you can isolate in a short discussion. But to say that train wheels are more efficient because they are less compliant is not only completely wrong, but does not apply at all when talking about tires.
You are half right here. When tires deform they do generate heat which results in rolling resistance. However, the stiffer a tire is the less it will deform thus less heat is generated thus less rolling resistance. The ultimate example is a train wheel on a steel track. Very little deformation thus very little heat generated thus very low rolling resistance. An example at the other extreme is a balloon tired dune buggy on a sandy beach. A lot of deformation in tire and surface thus a very high rolling resistance.

Consider why a underinflated tire has a higher rolling resistance than a properly inflated tire. The reason is the sidewall is less stiff and the contact patch is larger for the underinvested tire, resulting in more flexing of the sidewall and tread resulting in more generated heat thus higher rolling resistance.

I think you are assuming a stiff tire must flex just as much as a soft tire as it rolls thus since its harder to flex a stiff tire more heat is generated with a stiff tire. The error in your thinking is assuming a stiff tire flexes just as much as a soft tire. It doesn't.
 

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Interesting how things taken to extremes well describe even small differences. The train wheels are a good example. While tire mechanics are a complex subject, it's generally true that a less complient/overinflated tire will offer less rolling resistance thus greater mileage than a more complient/under inflated one.

Having said that, chassis are tuned for the pressure reccomendations usually appearing on the door frame or in the owners manual......normally for multiple good reasons.
 

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Ok thanks not much of a difference. 46lbs total.
Whoa! :eek:
Jaxterra said: " the OEM 18" wheel and tire weighs 49.5 pounds."
Charles H said "phev lx stock 16in wheels with snow tire sans wheel cover, 38lbs"
Back in the day that was a 11.5 lbs difference. Seems like a Big Diff (24%) to me. Am I missing something?

Somewhere else someone said stock wheels were 19 lbs. Stock tire accord to TireRack is 21 lbs, so 38-40 sounds about right. :nerd:
 

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You're not missing anything, that is indeed a considerable difference. Heavy wheels and tires create a double penalty. Just the added weight is a small detriment in acceleration and braking additionally that weight has to be overcome in angular momentum. Finally the suspension has to handle the additional weight complicating damping and control. Good to avoid unsprung weight where practical. Certainly worse than adding the same weight in cargo.
 

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I like my 18's way more than the 16's is why I was wondering so I'll stick with them. 46lbs not enough weight for a change for me.
 

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Discussion Starter #32
Thanks for the info guys...I think I will stick with the 18s....maybe I will think about again when comes to time to replace tires.
 

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Yeah I calculated it would cost $600 plus for new wheels alone and I'd save maybe $50 a year in fuel 50x10 years is $500 still doesn't cover the cost. And where I live fuel may be cheaper anyways we are at $2.25 now and was at $1.65 in the winter.


And I like the 18's!!
 

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To change the wheel size for the sake of it doens't make mathimatical sense. When the 18" wheels wear out and they will, you can look at the cost of selling your 18" rims and buying 16" with the lower cost tires and it might make sense. Then again it might not as I haven't run the numbers.
 

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Also the 18's may actually handle better than the 16's and despite KIA doing a good job making the 16's look decent, the 18's IMHO, look better.
 

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Also the 18's may actually handle better than the 16's and despite KIA doing a good job making the 16's look decent, the 18's IMHO, look better.
I agree the 18s look great. Dealer wanted $500 each for just the 18 wheels. I passed and bought good enough 16in after market for $120 each installed.
 

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However, the stiffer a tire is the less it will deform thus less heat is generated thus less rolling resistance.

Consider why a underinflated tire has a higher rolling resistance than a properly inflated tire. The reason is the sidewall is less stiff and the contact patch is larger for the underinvested tire, resulting in more flexing of the sidewall and tread resulting in more generated heat thus higher rolling resistance.
When a tire hits an impact, a tire must deform to a certain extent. When sidewalls are flexible, the tire deforms easily over the irregularity with the vehicle losing little momentum. With stiffer tires, they flex less but the impact now has to be absorbed with wasted heat. In addition, road irregularities cause micro (sometimes gross) air or the tire leaving the road. Every small loss of contact creates higher rolling resistance, again as wasted heat from increased friction.

Sure, and overinflated tires reduce rolling resistance on smooth roads by reducing contact patch area. Hypermilers will use narrow overinflated tires and ride the ridge or painted lines to take advantage of increased smoothness where their choice of tires and inflation have a clear advantage. Smooth roads (with the ultimate being your beloved steel rails) are where this strategy wins. On other surfaces, it loses in every regard, rolling resistance plus handling, comfort, braking, and tire life.

The ultimate example of this are off road tires. Road tires will be skipping and hopping at their normal pressures. A coast down test down a rocky bumpy hill will quickly reveal that those large low pressure tires actually have lower rolling resistance under those conditions. Road tires are designed for the middle between those two extremes of off road and steel roads and have design criteria considerably different.

Bicycle tires are a different animal and it is difficult to directly compare them. Yet I have a constructive example. Wider road bicycle tires (to a point) are routinely known and tested to have lower rolling resistance (has to do with lower pressure and how the contact patch interfaces with road surfaces). Tradition and air resistance stop road racers from using wider tires with pave racing or cyclocross being exceptions. I often go out on group road rides with local clubs where I'm the only one with one and a half inch tires - the rest on around one inch high pressure tires. Not really any noticeable difference in coasting down hills with the group (we would just be talking a few seconds over 10 miles, less at higher speeds due to the aero advantage of skinny tires). But where the effects were dramatic where we had to do a quarter mile on gravel surface. Everyone but me immediately dropped speed and had to work hard to maintain that pace. I just floated along, not as in a smooth road, but far easier than my fellow riders.

If we had car tires with skin walls, they would have lower rolling resistance but higher rates of failure from the tire sidewall touching obstacles minus a protective rubber coating. Bicycle riders have that choice, and tires without that stiff rubber side coating roll better, but of course fail more from sidewall damage.

Besides the issue of sidewall suppleness and rolling resistance, tire compounds also contribute greatly to rolling resistance in a comparable way. They are the point of contact with the road, and the better they conform to the road surface, the lower the rolling resistance as they don't skip or deflect forward and back which creates wasted heat.

Bias ply tires are obsolete. They were lucky to last 15,000 miles. Any tire rotation was creating heat trying to tear the bias layers apart. Radial tires greatly reduced rolling resistance by guess what! Increasing suppleness, the ability of the tire to conform to the road surface with substantially less heat than standard tires. I was around for the Michelin radial introduction and bought a set of tires (much more costly than standard tires at the time) and they did last for the advertised 40,000 miles. Radials have improved over the last forty years, had a set last 85,000 miles on my last car. Rolling resistance improved as a result, otherwise there is no way tires could last so long if they created as much heat as previously.

Efficient green tires are designed for low rolling resistance. While tire design is incredibly complex, these tires are more supple by design. This costs them for some other attributes such as handling, but they are a good compromise for non boy racers and their effect is more noticeable mounted on more efficient cars. But feel free to go no compromise your way and start riding on bare rims.
 

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The 16 inch rims are actually milled steel under the hubcaps, not black-painted aluminium. :)
 

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Yticolev's chart is accurate for either one particular tire model or an average of tires that size. There is some subtle variation on the overall diameter, width, and weight of tires of the same size. The variation is in the range of 1-2%

I'm a bit of a tire geek as I consider them on of the easiest, least expensive things one can change that will significantly affect multiple areas of a cars behavior. Those areas include road noise, ride comfort, cornering, and most importantly stopping under various conditions. Living in the PNW, one of my primary concerns is how well a tire stops in the wet - both when it is new and has 30,000 miles on it. The link below from CR provides measured data clearly shows how dramatically different well known, "premium" tires can vary. https://www.consumerreports.org/tires/what-happens-to-performance-when-tires-are-worn/

Tirerack is the best place to find size info (including revs/ mile), real data and consumer impressions of tire performance in various conditions.

For my rainy area and money, Michelin Crossclimate and Premier AS are the best. But YMMV
 

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There is zero data on the linked article. I think you have to have a subscription and be logged in to see anything of real interest. I do have online access via my library but this article is not available yet. A similar article from 2003 probably has similar information but no specific tire model recommendations or data. In wet, half worn tires hydroplaned at lower speeds, and had longer stopping distances. On dry roads, worn tire performance was better than new tires. That seems to be the entire takeaway.
 
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