Informal Range Poll: Uncovered Aero vs. Sport

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Which wheel/tire combo is most efficient overall?


  • Total voters
    41
  • Poll closed .

MichelT3

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#21
a range difference of 310 miles or 290 miles probably doesn't make that much of a difference either
For my expected use, it may mean getting it home after a workday, without charging in the middle of the night, or not.
In winter conditions, rainy / snowy road, headwind and heating on.
20 miles / 32 km means freedom of mind for me. So, yes, it matters a lot (not taking into account the effect of the Aeros).
 
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#22
With the model S owners have notice a decrease in range when the switched to larger rims. When you switch to a low profile tire this reduces the size of the side wall. The side wall needs to bend as the tire rotates. The side wall will need to bend more sharply on a low profile tire. This would cause the rolling resistace to go up. So the differace is aero dynamic drage and rolling resistance. This could be the reason for the big differance in range.
 

garsh

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#23
The side wall needs to bend as the tire rotates. The side wall will need to bend more sharply on a low profile tire. This would cause the rolling resistace to go up.
This is not correct.

The larger wheels that these tires are mounted on almost always weigh more. They also tend to be wider. And low-profile tires tend to have a stickier rubber compound for better handling. These are the things that cause them to not be as efficient.
 

LUXMAN

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#24
Here are the facts about wheel size vs performance. Performance is not related to the diameter of the rim, it is related to un-sprung weight. Un-sprung weight includes the suspension, breaks, wheels and tires. The rule of thumb is every pound of un-sprung weight is equivalent to 6 pounds of body mass. Stock 18” wheels (with Aero hubcaps) weigh 21.6 pounds, the 19” sport wheel weigh 29.5 pounds, that’s a difference of 7.9 pounds times 4 wheels = 31.6 pounds of un-sprung weight, when we multiply by 6 this is the equivalent of adding 189.6 pounds of weight to the car. If you think that this will not impact acceleration and range you are kidding yourselves. Add to that that the 19” rims require a lower profile tire which will decrease shock absorbing characteristics and give a stiffer ride plus they are more prone to sidewall issues from potholes.

The decision to go with 19” vs 18” is a decision to trade performance for appearance. It is definitely important that we love the way our car looks but do it understanding that you will be sacrificing acceleration speed, range and ride quality in exchange for the looks.

The 18” TST is advertised to weigh in at 26 pounds (I don’t believe there is one in production yet that can actually be verified) so from a performance perspective this is better that the 19” Tesla Sport wheel put still not as good as the stock Aero, the 18” TST would be the equivalent of adding 105 pounds of body mass, putting their performance somewhere between the stock 18” Aero’s and the 19’ sport wheels
Tsportline is saying on their site that the 18s with the covers are 23#s and 21.6 without
 

LUXMAN

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#25
This is not correct.

The larger wheels that these tires are mounted on almost always weigh more. They also tend to be wider. And low-profile tires tend to have a stickier rubber compound for better handling. These are the things that cause them to not be as efficient.
OK, but what is tire weight difference. probably not much but maybe a pound or two per tire.

And all this talk about range....is the 310 based on AeroCovers or Sport? I am assuming the tests were in the lab, so it doesn’t take in accountthe drag on the wheel since it came from a formula.
As in everything, YMMV
 

SoFlaModel3

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#26
OK, but what is tire weight difference. probably not much but maybe a pound or two per tire.

And all this talk about range....is the 310 based on AeroCovers or Sport? I am assuming the tests were in the lab, so it doesn’t take in accountthe drag on the wheel since it came from a formula.
As in everything, YMMV
Likely irrelevant since Motortrend got 334 miles, right? To that end 310 on Sports in the right conditions shouldn’t be an issue for us.
 

garsh

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#27
And all this talk about range....is the 310 based on AeroCovers or Sport? I am assuming the tests were in the lab, so it doesn’t take in accountthe drag on the wheel since it came from a formula.
Aerodynamic drag *is* taken into account. You are correct - most of the testing is performed on a dynamometer. But the dynomometer is programmed with each particular car's resistance factors.

Those factors are determined beforehand by performing a coast-down test. Hyundai has a good description of the process:
https://hyundaimpginfo.com/resources/details/coastdown-facts

There was nothing in the certification document describing which wheels were used during the test.
 
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#29
Tire sidewall has little to do with rolling efficiency.Also, hard to believe, but tire width has little to do with rolling resistance.
Wider tires do cause drop in range. Reason is actually due extra frontal area(s) and way worse aerodynamic drag of whole surface,
including alloy wheel surface.
And, in case of water on road, that too. And in case stickier rubber compound (very common on wide tires), that too.
 

John

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#30
As I've said before, I'm hoping Tesla will offer an 18" sport wheel, for all the practical reasons listed above. Even if they are a bit less efficient than the Aeros.
Here's what the 18" T Sportline wheels would look like—per my crude mashup—the ones available "march,april" for $1200. I didn't bother to put the Tesla cap back on them, or fiddle with the lugs.
(Yes, 5 lbs heavier each. But four choices of color, including two kinds of black for you "murderers" out there, so that's something.)
Maybe if I keep hyping these either T Sportline or Tesla will have them sooner?
I'd really like these to be a no-charge option that splits the efficiency gains of the Aero. But it may be that the Aero is still cheaper to make than these.

UPDATE: apparently these will weigh the same as an Aero with the hubcap on. Good news.
 
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Bokonon

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#31
Here's what the 18" T Sportline wheels would look like—per my crude mashup—the ones available "march,april" for $1200. I didn't bother to put the Tesla cap back on them, or fiddle with the lugs.
I like your 18" TST mockup better than the one I made a few weeks ago (which I deemed not good enough to share). :)

FWIW, TSportline mentioned on TMC that they expect to have photos of a blue Model 3 with their wheels sometime this week, so hopefully we'll be able to see the real deal soon enough (hopefully in 18", and hopefully in silver...).

bluewithtst18as-png.4372
 
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roflwaffle

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#32
Aerodynamic drag *is* taken into account. You are correct - most of the testing is performed on a dynamometer. But the dynomometer is programmed with each particular car's resistance factors.

Those factors are determined beforehand by performing a coast-down test. Hyundai has a good description of the process:
https://hyundaimpginfo.com/resources/details/coastdown-facts

There was nothing in the certification document describing which wheels were used during the test.
I think the application references the Aero wheels.

https://www3.epa.gov/otaq/datafiles/FOI_HTSLV00.0L13_APPIPT1.PDF

Page 16 has the road load horsepower (RLHP) for the Aero wheels at 50mph of 9.95, and the range test results on page 15 are using that same value.

At the same time, the SAE J1634 test results don't specify what the RLHP was, so... yeah?
 

garsh

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#33
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#34
Aero verses the sport rims each has its advanages and disadvanages.
The sport rims just look way better than the aero rims. The sport rims will give you slightly better handling.
What you will giving up will be a less smother ride. Slight reduction in range. Rims that are more prone to damage from pot holes.

If you drive at speeds below 50 mph the improvement in range will be less pronounced.
If you do a lot of freeway driving a need to get the maximum range out of the vehicle then the aero rims should be considered.
 

MichelT3

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#36
If you do a lot of freeway driving and need to get the maximum range out of the vehicle then the aero rims should be considered.
Exactly why I want 18" plus Aeros. (And we have a lot of wet weather.)
 

John

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#37
This has not been verified actually.
Different vehicle though theory is the same:
Good video. As I watched, I was wondering how to apply it to Model 3 and its wheel choices. Of course, the wheels have different widths (225 mm for the GTI, 235 mm for the Model 3. And the cars have different weights (about 3000 for the GTI, 3838 for the Model 3 LR).
Not sure how much it matters, but GTIs have traditionally been very front-heavy.

Here's some comparisons. In some cases, the 18" conclusions apply to the 19" Model 3 wheel.

Maybe just by profile?
Each row below is the same (in other words, the 17" GTI profile of 45% is equivalent to the 18" Model 3 of 45%.



By height of sidewall?


Once again, the larger Model 3 wheel lines up with one size smaller on the GTI.
The >'s are just my pointers to the sorting row.

By cross-sectional area / pound of weight?
Maybe more of a gauge of "air spring per pound."
When weight is spread over a wider tire, there is less stress on the sidewall.
(Note, this is not contact patch area.)
Here the sizes are roughly equivalent.



By contact patch area?
By weight / contact patch area?
 

Mad Hungarian

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#39
So what do you think will provide the least rolling resistance and/or most range: 18" Aero wheels with no covers and Michelin MXM4 tires vs. 19" Sport wheels with ContiProContact tires. They look to be the same width, with the 18" tire being 45 series and the 19" being 40 series. Both look to be classified as Grand Touring.

My guess is that the Uncovered Aeros still win at all but high speeds. Of course without a Mythbusters budget, we'll never know. But this forum is built on speculation!
Wow, I got dizzy reading how far off the reservation this thread went... although it's been interesting.
To answer @Rich M 's original question, I'm pretty onboard with the hypothesis that the uncovered Aeros will win the range war in stop/start city cycles and the 19" Sports will be marginally better at steady-state highway speeds. Meaning for someone running a typical mixed-cycle the difference might be a wash.
Part of this is based on a theoretical study I did for Kia Canada when we were asked to provide some winter wheels for the Soul EV and I needed to present the pros/cons of a few different off-the-shelf designs, some having a weight advantage and others an aero advantage.
However I also started an extensive series of real-world tests this past summer on my 2013 Volt comparing the optional OE 17x7.0 forged Aero wheels with 215/55R17 Goodyear LRR tires and a much more performance-oriented setup using our Fast FC04 competition wheel in 18x9.0 with 235/45R18 Continental PureContacts (also LRR). The premise was if one chose wisely, one could seriously improve the car's handling and looks without destroying the range. As the new 18" assembly weighed only 1.5 lbs more than the OE 17", I figured the city cycle would be a near wash, but the very open, spindly design of the FC04 (very similar to the uncovered aero M3 wheel) would be a problem on the highway.
I was only able to complete the highway tests before the weather started to get too cold, as I had imposed a 18C to 23C window on all runs to ensure that temperature variance wouldn't affect battery performance.
The tests were done on a lightly travelled new highway in my area, and consisted of a 2-way run of 60 km (37.5 miles), with the turn around occurring at just about exactly the midway point to correct for any winds. Speed was locked in at 100 km/h (62.5 mph) for the duration. Car was always fully charged overnight and driven the short distance to the highway in the exact same manner every morning. No radio or accessories used, HVAC set to fan-only at speed 2.
5 runs performed on each set.
Results?
On average the open-design 18" wheels on 235/45's dropped the range by about 8% compared to the closed 17" on 215/55's. Now of course my test had the additional significant variable of the tire being 20mm wider and that definitely added even more aero resistance. But I estimate that if I had run a 215 in 18" I'd still have seen at least a 4% - 5% drop due to the wheel drag. If that were to be the case, and my theory that the city range will be very close turns out to be correct, then it would mean that the overall loss in a mixed city/highway cycle for the average driver would probably work out to around 2% - 3%. Even if it turns out to be on the higher side of that range, the performance improvement is BY FAR worth it, simply no comparison in how much more fun the car is to drive. Way sharper steering response and much higher cornering limits with very little loss of comfort.
So city tests to come in the spring, and for the benefit of the have-your-cake-and-eat-it-too crowd I'm also going to have some flat aero covers made for the 18" FC04's to see how much highway range can be recouped.

And of course you can bet that I'll be doing it all over again once I finally have my 3 ;)
 
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Mad Hungarian

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#40
Tire sidewall has little to do with rolling efficiency.Also, hard to believe, but tire width has little to do with rolling resistance.
Wider tires do cause drop in range. Reason is actually due extra frontal area(s) and way worse aerodynamic drag of whole surface,
including alloy wheel surface.
And, in case of water on road, that too. And in case stickier rubber compound (very common on wide tires), that too.
Arnis, you are right about the range loss due to width increase being primarily about drag.
However I have to correct you on the tire sidewall not being a factor, it is actually one of the biggest ones due to the energy consumed by hysteresis, the constant deformation of the sidewall at the bottom of the tire (the "bulge") as it rotates. There's a pretty good article explaining the basics here. Note that last factor, number 13:
"Internal tire architecture. The type of internal tire architecture used on a given vehicle has by far the most pronounced effect on tire rolling resistance, operating temperature, tire tread life and other vital aspects of tire performance."

As a result, a lot of the biggest improvements in LRR tire design have come from optimizing the materials and construction techniques, especially in the sidewall, to reduce these parasitic energy losses.
 
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