Leaf wheel questions

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jimmol

Member
Joined
Aug 16, 2017
Messages
18
It is time to replace my summer tires and after reading various and sundry posts about wheel and tire size, I am leaning toward putting 16 inch wheels in the hope that I might gain a bit more milage out of my battery in my 2015 leaf. It still has 12 bars at 49000 miles and 20.5 kW available/90.28 SOH.
I have some questions about wheel rims that I would like your input..

Width: the 16” Leaf wheel has 6.5” wide rims, I believe, is it alright to go wider as long as the tire will fit it?

Do rims have load ratings? If so what load rating do I need for my 2015 Leaf SL? (The Enkei RPF1 is the only one to list a Load rating of 690 https://www.vividracing.com/enkei-rpf1-wheel-racing-series-silver-16x7-5x1143-43mm-p-150931607.html?cat=6424)

Offset: 40 mm. Can the offset be higher? If so, by how much?

The rims I am looking at come with centering rings. Can anyone explain what they do? I though the lug nuts would center the wheel.

All of the rims offered covers for the center. Is this necessary?

On the tire rack site, all the rims recommend 205/55-16. Would there be any problem going to a 205/60-16?

I am considering two rims that weigh in at 18 lbs: Focal F20 and the Motegi Racing MR143 cs6. The Enkei Racing RPF1 caught my eye at 14 pounds, but at a price.

On to the tires:
To keep the speedometer and odometer close to the values using 17” tires, I am thinking of using 205/60-16 ECOPIA EP422 PLUS tires (51 psi max) which will make the tire 1/4” taller and will make the actual car travel at at 65.5mph when reading 65 on the speedometer. Plus this tire weighs in at 19 lbs., 3 pounds less than the 17”. Add to that the savings of a smaller rim - someone said the 17” were around 25 lbs. - comes out to around 10 lbs., maybe even 14 lbs. less per wheel.

As to how many more mile can range depends on who you listen to: One video implies it will add up to 10+% while others have said there is a noticeable difference to those who doubt it will save much at all.

But for me, I need new tires, want to get wheels so all I have to do each year is swap out, and maybe get them balanced before hand, so now might be a good time to try to smaller rims, unless one of you can talk me out of it.

Thanks for your help and input for selecting the correct wheel rim.
 
I have been pretty happy with my 16" ev01+ rims. They are 15.9 Lbs a piece without the inserts (add a couple 9unces per insert).

I have the stock Ecopias on the rims, but I like the idea of going to a 60 height tire.
 
Offsets can vary but the farther away from stock you get the more the handling will be affected. If you have wider or narrower wheels a different offset can accommodate this difference a bit but I'd try to stay close to stock. The centering rings are used to center the wheel on the hub. Some wheels are hub-centric meaning the hub hole centers the wheel and some wheels are bolt-centric meaning the wheels are centered by the bolts. I'd guess that the shape of the lug nuts/bolts and mounting holes are different on bolt-centric wheels than hub-centric but I'm not an expert.

Don't forget you'll need new TPMS sensors. I bought some on Amazon that specified they were made for my model year Leaf and then had someone with an Autel tool match them to my car. I had some others I got from ebay that said they worked with Nissan that didn't work so be sure to get something that is made for your model Leaf and then expect to have to pair them with the car.
 
DougWantsALeaf said:
I have been pretty happy with my 16" ev01+ rims. They are 15.9 Lbs a piece without the inserts (add a couple 9unces per insert).

Thanks for weighing in.
I had read about this from your "EV01+ with aero covers" post. I did email and "attention: Chris" last Tuesday and am awaiting a reply.
So if you use the inserts, it adds 2.8 pounds. Good to know.
The 60 raised the car back to original height so you lose any benefit of lower profile.
If you don't mind, could you pm me the price you paid for the 16"?

Thanks again
 
goldbrick said:
Offsets can vary but the farther away from stock you get the more the handling will be affected. If you have wider or narrower wheels a different offset can accommodate this difference a bit but I'd try to stay close to stock.
It appears, in this case, that the offset would barely change the tire location as compared to the 17" tire, if my math is right.

The 16" tire is .39 (9.91mm) narrower. Every rim is 1/2" wider. Only one rim, the RPF1, has a 43mm offset vs the others with a normal 40mm. So:

The 43mm offset would move the wheel center 3mm away from the hub mounting surface toward the car, which means the car side edge of the wheel would be closer to the car and back from from the curb.

The narrower tire would move the tire on the car side 4.9mm away from the car and 4.9mm away from the curb, if I am thinking right.

The 17" wheels have a 46mm offset.
The 16" rim would move the wheel center 3mm toward the curb. The 16" smaller tire width would move the side of the tire back 4.9mm from the curb, ending up with the curb/outside edge of the tire being 1.9mm further from the curb than the 17" tire.
Meanwhile, on the car side...
The 16" rim would move the wheel 3mm away the car. The 16" smaller tire width would move the side of the tire back 4.9mm from the car, ending up with the car/inside edge of the tire being 7.9mm (0.31") further from the car than the 17" tire.

The stick diagram below is a simple illustration.
[_|_____|] [____] original 17"tire |___| 16" tire

Centering rings make better sense and I am hoping that Tirerack will be carrying the proper Nissan TPMS sensors.

Appreciate your time.

I apologize for the multiple edit on this post, but I have never considered offset until a few days back. It has taken me 5 posts to get close to what I think is right, if it is right. Instead of making a different post to verify it, I tagged on, please check my math.

Tire size differences Original 215/50-17 new 205/60-16
https://www.discounttire.com/learn/tire-size-calculator
Offset diagram
https://www.tirerack.com/images/wheels/tech/offset.gif
 
That math is making my brain hurt, but I run 205/65R16 Goodyear Assurance year-round (quite a bit of extra grip, fairly low rolling resistance, and nice ground clearance) and am happy with them. They are on the original steel wheels with the centers uncovered. Long term efficiency reads 4.7 m/kWh.

The speedometer reads only slightly high...about 0.5 mph high at 35 mph. The taller tires also let me use the temp spare from a Maxima.
 
I am thinking 205/65/16 might be the way to go. I do like the idea of a more aligned speedo. The stock tires on the S+ are off by about 2.5 mph at 70mph from my GPS readings. It probably keeps me out of trouble.

The useless upgrade side of my brain still thinks dropping the car an inch or 2 might add a little highway performance.
 
I looked at the larger tire size and found, via the tire size calculator, that the speedometer would read nearly 3mph high and it would raise the car up nearly an inch from the 17" wheel.
For me, I would like to have the speedometer as close as possible while I drive around town.

I am leaning toward the Enkei Racing RPF1 and the Ecopia EP 422 Plus at the 205/60-16, if I can afford the setup. I like the idea of taking 11 pounds off the rim and 3 more off the tire, giving me a reduction of 14 pounds per tire.

One of the posts I read mentioned that taking weight off the wheel helps in acceleration but did not help in driving along. I do not recall why they said this, but as I thought of it... is driving down the road a series of accelerations to keep the speed constant? When you come to the hill on the road, don't you add power (accelerate) to keep the car going up the hill at a constant speed?

I believe they also mentioned that light wheels reduce regeneration. Hmm. If you have a 3000# mass going down a hill, it won't care what weight the tires are on the car. The go around 780 times per mile whether they are light or heavy. The revolving of the tire causes regeneration. Maybe I am wrong...


https://www.discounttire.com/learn/tire-size-calculator
 
jimmol said:
One of the posts I read mentioned that taking weight off the wheel helps in acceleration but did not help in driving along. I do not recall why they said this, but as I thought of it... is driving down the road a series of accelerations to keep the speed constant? When you come to the hill on the road, don't you add power (accelerate) to keep the car going up the hill at a constant speed?
Technically, lighter wheels, reduced weight will. But... drag is what hinders the acceleration. Before hitting wind resistance, the more drag the tires have, the slower the acceleration. That is why inflating the tires increases acceleration, you are reducing drag and traction also. Too little traction and you just burn rubber and go nowhere. You have to find the balance between enough grip to accelerate but not so much it drags or so little it just slips. Driving down the road is a waveform of acceleration and deceleration.

I believe they also mentioned that light wheels reduce regeneration. Hmm. If you have a 3000# mass going down a hill, it won't care what weight the tires are on the car. The go around 780 times per mile whether they are light or heavy. The revolving of the tire causes regeneration. Maybe I am wrong...


https://www.discounttire.com/learn/tire-size-calculator
Physics say yes, but the amount might be 0.000001 %, so you might not really notice. :mrgreen:
 
jimmol said:
...

On the tire rack site, all the rims recommend 205/55-16. Would there be any problem going to a 205/60-16?

....

Definitely go with the 205/60 R16". I have 205/55 R16" winters and they are noticeably smaller than the 215/50 R17" OEM rims/summer tires on my 2018 LEAF SL. The calcs below show a .7" difference which is pretty consistent with a side to side actual comparison of the tires.

OD on the 215/50 R17 is 25.46"
OD on the 205/55 R16 is 24.88"
OD on the 205/60 R16 is 25.69" (closer match to OEM)

The leaf is already low, so particularly in winter, I'd rather have a bit more height than less.
 
I suppose angular momentum may be the factor that makes heavier, larger diameter wheels require more energy to accelerate and offer more regeneration when slowing. Think of the wheels as flywheels. The heavier and larger diameter they are, the more rotational energy they store (and the more difficult it is to accelerate and decelerate them).

Once heavy flywheels are spinning, it doesn't take much to keep them spinning (highway cruising), and their rotational energy can help balance small climbs and descents.

Okay, I'm up for some brain melting--hope I'm doing this right...

Using a rotational kinetic energy (easier to calculate) online calculator and 785 rpm for about 60 mph:

16" 13.7 lb wheel: 325 J x 4 = 1300 J

17" 24.7 lb wheel: 662 J x 4 = 2648 J

That's more difference than I expected!

The rest of the car, though, (3300 lbs) has about 538,500 J of kinetic energy at 60 mph, so the effect of the wheel mass is still pretty limited.
 
DougWantsALeaf said:
So how much loss do you think there is in the starting and stopping cycle? Also, with rolling resistance, how much loss (delta between wheels) do you think that creates?

Good questions! :D

I don't know, but for typical use (not racing or competing in efficiency competitions), I don't think these types of differences in wheel/tire weight and diameter are enough to go out of one's way over.

I suspect that lighter weight always has efficiency benefits (although possibly slight), even if it means less momentum.

Now, this type of application is a different story:

Oversized-Tires-1-1280x720.png
 
Ok, just did a run between Skokie and Pontiac IL today, 219 miles round trip. As an aside up front, if passing Pontiac IL, stop to Charge. There is a special non affiliated 4 station DC charging stop. The place "Wallys" is road trip stop heaven including a beef jerky counter, 12 slurpee flavors, and dozens of soda tap options. Retail, etc... insane. This is a vision of the future for evs.

The highway around the city bypass is 60 mph, and the route down progressively moves to 70 mph for reference. Head winds on the way down. Tail winds back. 80-84 F ambient.

3.9 miles per kWh down (108 miles) and an amazing 5.1 back (111 miles).

Here is a graph of the battery temps for the 4 hours. The DC charge added about 12F to the battery. Due to tail wind and low consumption, temp actually reduced a tiny bit on way home (maybe 1-2 degrees).

https://drive.google.com/file/d/17_YHYsa3CllsEcYf68_4QvUA-zIIegXG/view?usp=drivesdk

I feel like the rims help, especially when above 70mph.
 
PrairieLEAF said:
I suppose angular momentum may be the factor that makes heavier, larger diameter wheels require more energy to accelerate and offer more regeneration when slowing. Think of the wheels as flywheels. The heavier and larger diameter they are, the more rotational energy they store (and the more difficult it is to accelerate and decelerate them).

Once heavy flywheels are spinning, it doesn't take much to keep them spinning (highway cruising), and their rotational energy can help balance small climbs and descents.

Okay, I'm up for some brain melting--hope I'm doing this right...

Using a rotational kinetic energy (easier to calculate) online calculator and 785 rpm for about 60 mph:

16" 13.7 lb wheel: 325 J x 4 = 1300 J

17" 24.7 lb wheel: 662 J x 4 = 2648 J

That's more difference than I expected!

The rest of the car, though, (3300 lbs) has about 538,500 J of kinetic energy at 60 mph, so the effect of the wheel mass is still pretty limited.
Rotational mass is only important for acceleration and deceleration, However sprung mass affects damping and handling so the lighter rims will improve the ride quality and handling.
 
Thanks to all of you who contributed to this thread.

I have ordered the Enkei Racing RPF1 16 x 6 wheels and ECOPIA EP422 PLUS tires 205/60-16.

I hope to have them installed by April 20 and will report back later.

If I forget, just leave and post and it will remind me.

Thanks again.
 
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