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TomT
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Re: range impact of wheels/tires

Thu Nov 10, 2011 2:29 pm

Wheel weight is really not going to make that much difference. At a steady state speed it will make virtually no difference. Aerodynamic drag is a far bigger influence.

charlestonleafer wrote:I'm still wondering what the impact would be of replacing the wheels, with some lighter wheels, but keeping the same tires. There must be some calculations out there, not only for LEAFS, but for vehicles in general. If we could get some studies from another vehicle, at least we could get a starting point.
59,991 miles/12 bars/289 Gids/68.54 AHr/101% SOH/101.64% Hx 7May15 w/ new Lizard (barely made the warranty).
71,770 miles/12 bars/256 Gids/59.04 AHr/88% SOH/87.92% Hx 3Mar16 at lease return.

Now driving a 2016 Volt Premier.

Herm
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Re: range impact of wheels/tires

Thu Nov 10, 2011 2:52 pm

TomT wrote:Wheel weight is really not going to make that much difference. At a steady state speed it will make virtually no difference. Aerodynamic drag is a far bigger influence.


All that is true of a highway cruiser, but for a city car with limited hwy range like the Leaf speed will be slower and speed will vary a lot.. thus wheel weight is very important.

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drees
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Re: range impact of wheels/tires

Thu Nov 10, 2011 3:38 pm

Herm wrote:
TomT wrote:Wheel weight is really not going to make that much difference. At a steady state speed it will make virtually no difference. Aerodynamic drag is a far bigger influence.
All that is true of a highway cruiser, but for a city car with limited hwy range like the Leaf speed will be slower and speed will vary a lot.. thus wheel weight is very important.

Tom is right - unless you're dropping wheel weight by a very significant amount, you're not going to notice.

As a general rule of thumb, dropping 1 lb of wheel weight will be similar to dropping 2 lbs of non-rotating weight. So let's say you replace the stock 20 lb wheels for some 15 lb wheels for a total weight reduction of 20 lbs. This is like removing 40 lbs of weight from the vehicle. I doubt you'll see any difference unless you have very precise measuring instruments.
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cwerdna
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Re: range impact of wheels/tires

Thu Nov 10, 2011 5:49 pm

Although this wasn't done on EVs, those participating in this thread might find these interesting:
http://www.tirerack.com/tires/tiretech/ ... techid=177
http://www.tirerack.com/tires/tests/tes ... p?ttid=121

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TickTock
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Re: range impact of wheels/tires

Sat Jun 09, 2012 10:02 am

TomT wrote:Wheel weight is really not going to make that much difference. At a steady state speed it will make virtually no difference. Aerodynamic drag is a far bigger influence.

charlestonleafer wrote:I'm still wondering what the impact would be of replacing the wheels, with some lighter wheels, but keeping the same tires. There must be some calculations out there, not only for LEAFS, but for vehicles in general. If we could get some studies from another vehicle, at least we could get a starting point.


Makes me think I should be looking for full face, closed/spokeless rims but choices are very limited for sizes < 20" (for any size, really due to the lack of airflow for the brakes I guess). The closest I found was this in 18x7.5 (even 17x7 if you don't want to deviate as much).

http://www.thewheelconnection.com/wheel ... ndsearch=1

Image

but can't find the weight or offset. Ideally, there would be no holes at all and Since we rarely use the friction brakes this should be OK. Thought I pair up the 17x7 with the 215/45 Yokohama AD08 from the Porche/Leaf video or go 18x7.5 and 225/40.

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Nubo
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Re: range impact of wheels/tires

Sat Jun 09, 2012 11:31 pm

aqn wrote:Re. weight: we're not talking about just "weight". We're talking about weight in rotational components. Increase in rotational weight == an increase in moment of inertia == bad. How much worse? Don't know, but it's definitely not better!


Keep in mind though the rotational weight is only a factor during acceleration. In steady-state cruise it's just ordinary weight.
I noticed you're still working with polymers.

DaveinOlyWA
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Re: range impact of wheels/tires

Sun Jun 10, 2012 8:16 am

larger wheels OF THE SAME WEIGHT do lower your gas mileage.

take an umbrella. the kind that has a hook on the end. put the umbrella between your two hands and roll the umbrella back and forth. you are spinning the umbrella but with relatively minimal effort. now, take that same umbrella and spin it around your hand by the hook on the end. the weight of the umbrella has not changed but the effort you expend has increased and you are most likely not spinning the umbrella as fast as you were before.

but i see it all the time. get some standard 16" wheels normal profile tires, get 30 mpg. then they decide to put on 20" wheels with low profile tires with difference in weight that does adds up to a few lbs.

but the mileage drops to 25 MPG and its the same story..."oh ya, new tires take time to break in but your mileage will go back up a bit" and it probably will...to 26 at the most.

there is a reason why early Japanese imports had 12 and 13 " wheels. it was because that is what they needed to do to get better mileage. now that technology has improved a bit, tires are getting larger. after all, they ride better
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TomT
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Re: range impact of wheels/tires

Sun Jun 10, 2012 8:44 am

In the case of the umbrella it is much more because of increased aerodynamic drag relative to the very light weight and large size of it. Such is not nearly the case with a wheel and it really is not a good analogy. (I went from 17" to 18" wheels on my BMW shortly after I got it and noticed no statistically significant difference in mileage when I did...)

I also contend that the small wheels on early imports had nothing to do with mileage and everything to do with cost. They were trying to build them as cheap as possible back then.

DaveinOlyWA wrote:larger wheels OF THE SAME WEIGHT do lower your gas mileage.

take an umbrella. the kind that has a hook on the end. put the umbrella between your two hands and roll the umbrella back and forth. you are spinning the umbrella but with relatively minimal effort. now, take that same umbrella and spin it around your hand by the hook on the end. the weight of the umbrella has not changed but the effort you expend has increased and you are most likely not spinning the umbrella as fast as you were before.

but i see it all the time. get some standard 16" wheels normal profile tires, get 30 mpg. then they decide to put on 20" wheels with low profile tires with difference in weight that does adds up to a few lbs.

but the mileage drops to 25 MPG and its the same story..."oh ya, new tires take time to break in but your mileage will go back up a bit" and it probably will...to 26 at the most.

there is a reason why early Japanese imports had 12 and 13 " wheels. it was because that is what they needed to do to get better mileage. now that technology has improved a bit, tires are getting larger. after all, they ride better
59,991 miles/12 bars/289 Gids/68.54 AHr/101% SOH/101.64% Hx 7May15 w/ new Lizard (barely made the warranty).
71,770 miles/12 bars/256 Gids/59.04 AHr/88% SOH/87.92% Hx 3Mar16 at lease return.

Now driving a 2016 Volt Premier.

thankyouOB
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Re: range impact of wheels/tires

Sun Jun 10, 2012 9:30 am

since the Nissan folks added those headlights to reduce drag from the mirrors, what makes you think they didnt calculate the wheels' aerodynamics in the choice of stock?
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Smidge204
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Re: range impact of wheels/tires

Sun Jun 10, 2012 12:14 pm

thankyouOB wrote:since the Nissan folks added those headlights to reduce drag from the mirrors, what makes you think they didnt calculate the wheels' aerodynamics in the choice of stock?

based on what I heard from various Nissan peoples, the headlight design was initiated to reduce NOISE. Since the car is so quiet, the wind noise was a concern and they took steps to mitigate it. Reducing drag was, I think, a bonus rather than the goal.

If they really wanted to focus on reducing drag as a priority, the LEAF would have wheel skirts. :lol:
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