DaveinOlyWA
Posts: 15893
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: Gen II light weight wheels and tires

Fri Jan 14, 2022 2:15 pm

watchdoc wrote:
Fri Jan 14, 2022 11:45 am
DaveinOlyWA wrote:
Fri Jan 14, 2022 9:22 am
We are not looking at "unsprung weight" We need a rotational mass calculation to quantify the difference. An 8 lb difference is significant. The wheel size to efficiency effect I first discovered while perusing the 2010 Prius during its reveal at the 2009 Detroit Auto show. While looking the car over, we found the engineer's notebook in the car and started thumbing thru it. As you would expect; most of it was unreadable but the page stating a the mpg differences between tire sizes was unmistakable.

F = m*v^2/r
Summarize your point for me please. So you're saying skinnier tires has more effect than unsprung weight?

The combo I'm looking at would be greater than 10lbs per corner lighter but retain the stock 215 tire size.

This article seems to indicate that tire width is much less important than rolling resistance and wheel size.

https://www.greencarreports.com/news/11 ... icle-range

So here's my question. assuming everything else is the same (same tire, same width, same total diameter, same total weight) would a 16" wheel and tire combo be more efficient than a 17" wheel and tire combo? If so, why???
Question; its the weight. smaller wheel diameter simply means taller tire so overall diameter would be the same or very close to it. The reality is driving on low profile tires is well... I don't know. I don't know why people think they are cooler, look better or anything else for that matter.

The shorter sidewall means less flex so more beefing to be able to handle the degrading American infrastructure.

Looking at the formula and determine what changes. In your question, only the mass changes. If the wheel size actually did control the diameter, then yeah, efficiency would skyrocket but the difference is pretty small but a 25% difference in weight is significant.

As far as the article, its right only in that more efficiency is not a one shot deal. Its a lot of stuff; LRR tires, max safe tire pressure, smaller wheels which are almost always lighter than tires unless you get the super expensive alloys which I know some that have and they don't seem to hold up well over time but never really got many details on it simply because it wasn't possible to get a favorable ROI.

You want efficiency; use constant power, minimize sprints and regen and never use braking if possible. Now all that is a challenge but every second you make it is a bump on the range and also good for the battery as well. We all want the gentle life and your pack is no different.
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 25,047 mi, 92.12% SOH
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knightmb
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Joined: Mon Jan 12, 2015 7:41 pm
Delivery Date: 26 Feb 2021
Leaf Number: 306291
Location: Franklin, TN

Re: Gen II light weight wheels and tires

Fri Jan 14, 2022 2:17 pm

Skinny tires do have slightly less air resistance, but the energy savings is very small. Lighter wheels have less rotational energy, thus less energy to drive them *and* steer them. Basically you are replacing metal with air on smaller rims and bigger tires. The weight savings adds up over the long run and saves energy, which for an electric vehicle can be a lot of miles. Bigger tires also means less chance of damaging the rim in a deep pothole and better shock absorption for a smooth ride.
On a Tesla Model 3 for example, just changing from 20" rims to 18" rims (same wheel diameter while traveling at 75 mph) gains you 39 miles in range. It's no magic, just lighter wheels that take less energy to drive. ;)
watchdoc wrote:
Fri Jan 14, 2022 11:45 am
DaveinOlyWA wrote:
Fri Jan 14, 2022 9:22 am
We are not looking at "unsprung weight" We need a rotational mass calculation to quantify the difference. An 8 lb difference is significant. The wheel size to efficiency effect I first discovered while perusing the 2010 Prius during its reveal at the 2009 Detroit Auto show. While looking the car over, we found the engineer's notebook in the car and started thumbing thru it. As you would expect; most of it was unreadable but the page stating a the mpg differences between tire sizes was unmistakable.

F = m*v^2/r
Summarize your point for me please. So you're saying skinnier tires has more effect than unsprung weight?

The combo I'm looking at would be greater than 10lbs per corner lighter but retain the stock 215 tire size.

This article seems to indicate that tire width is much less important than rolling resistance and wheel size.

https://www.greencarreports.com/news/11 ... icle-range

So here's my question. assuming everything else is the same (same tire, same width, same total diameter, same total weight) would a 16" wheel and tire combo be more efficient than a 17" wheel and tire combo? If so, why???
2020 Leaf SL Plus - (Manufacture Date March 2020)
2018 Leaf SL - (Manufacture Date February 2018)
2013 Leaf SV - (8 faithful years of service before trade in at 75,679 miles LeafSpy-Data)
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DougWantsALeaf
Posts: 3104
Joined: Fri May 10, 2013 8:21 pm
Delivery Date: 18 May 2013
Leaf Number: 407811
Location: Chicago North Side

Re: Gen II light weight wheels and tires

Fri Jan 14, 2022 6:42 pm

Smaller wheels also tend to move more mass to the center of the wheel and away from the edge, which is more efficient.
2019 S Plus (93.1% SOH) & 2019 SV Plus (90.7% SOH) Both Silver
2013 Leaf SV sold 2019 with 11 bars
100 Mile Club Member (Number 87)
Max Miles on 13 Leaf: 120 miles
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sreidvt
Posts: 1
Joined: Mon Nov 22, 2021 12:03 pm
Delivery Date: 22 Nov 2021

Re: Gen II light weight wheels and tires

Sat Jan 22, 2022 12:21 pm

HerdingElectrons wrote:
Wed Jan 12, 2022 10:36 am

The wheels are 16x7 and supposedly weigh 18.92# each. I ended up using Ecopia 422+ tires and the combined weight measured by me holding the mounted combo on my personal scale & then weighing myself was 39.8#'s

Last March I paid $965 before tax for the wheel/tire combo.

http://www.veloxwheels.com/wheels/mantra
38mm offset and IIRC 114.3 bolt pattern

I typically see a 3-10% improvement in consumption & the car felt more lively under initial acceleration.
Where did you order that tire combination from? Thanks.

HerdingElectrons
Posts: 248
Joined: Sat Sep 08, 2018 3:20 pm
Delivery Date: 17 Sep 2018
Location: Central Coast, Ca

Re: Gen II light weight wheels and tires

Sat Jan 22, 2022 8:21 pm

sreidvt wrote:
Sat Jan 22, 2022 12:21 pm
HerdingElectrons wrote:
Wed Jan 12, 2022 10:36 am

The wheels are 16x7 and supposedly weigh 18.92# each. I ended up using Ecopia 422+ tires and the combined weight measured by me holding the mounted combo on my personal scale & then weighing myself was 39.8#'s

Last March I paid $965 before tax for the wheel/tire combo.

http://www.veloxwheels.com/wheels/mantra
38mm offset and IIRC 114.3 bolt pattern

I typically see a 3-10% improvement in consumption & the car felt more lively under initial acceleration.
Where did you order that tire combination from? Thanks.
Costco Tire Center & I edited the original post I made to reflect that.
2018 SL Pearl White 4.5/3.9; 5.0/4.6 with 205/65/16 tires)

09/18-01K Mi: 114.52AHr / SOH= 99.20%
04/19-10K Mi: 111.45AHr / SOH= 96.54%
11/19-20K Mi: 107.44AHr / SOH= 93.07%
12/20-33K Mi: 105.39Ahr / SOH= 91.29%
04/21-35K Mi: 104.32Ahr / SOH= 90.37%

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