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Upgraded to 22's and ate 20% efficiency?

For those that have upgraded to a 22" wheel set, have you noticed a difference in efficiency? After my additions, it looks like I've gone from an average energy usage of 320Wh/mi to about 380Wh/mi. If it's not the wheels, then it's the 5.8.4 update that just pushed... Thoughts? (Side note: I'm waiting for wheel and tire weight from the manufacturer as I type this)

I would look into the difference in rolling resistance.

I'll definitely do that. Thanks! I also just thought about the fact that it was 60s~70s F when I first drove with the 19s and it is 30s-40s with the 22s on now. I wonder how much that affects the battery usage?

In that case, temperature could explain it entirely.

that's like fresh orange juice to frozen orange juice - don't quite compare.

Side note: I went from the stock 19s to CEC C881s in 22". I had 400 miles on the 19s and about 200 on the 22s now.

Really Bighorn? Are people in very cold climates really experiencing that much of a battery usage difference than us in warmer climates (I'm in Texas)?

21s are about 3% less efficient than 19s, so depending on your tires I would expect a bit more than that 20% seems a bit much just for the wheels/tires.

I see about 5% more energy use running my 20" wheels with 265-wide tires for the track, but they are much stickier tires than even the extreme summer tires on the 21s.

Any chance you've added too much "overdrive" and are lugging it?

bigger wheels sound like a downgrade if the S can't go as far

@G.
Absolutely--even more when doing short jaunts. 400-500Wh/m when car is really cold. First couple miles can see close to 1000Wh/m with battery warming and climate control.

What is the weight of the old wheel vs the new--bigger wheels are likely going to give you higher rotational inertia.

O

+1 Bighorn: I have seen my short commutes have a 20+ increase in energy use now that we have temps in the 30s. Rolling resistence, heating the cabin/seats AND battery. Longer trips even out better
but trips of less than 5-10 miles eat up the electrons

20+ is 20%+

Believe it or not, much of it is the density of cold air. Heavier, more viscous.

Sounds more liked a downgrade to me. I just drove my wife's S85 car with 19's and have to admit they are quieter and smoother than my plus with 21's.

I am thinking about "upgrading my 21's to 19's for the ride and noise comfort.

Its the wheels. I went from 19" to 21" and lost a lot, I know burn through energy faster. Love the 21"s so they are staying.

noob question.

Is the outer diameter of the tyres the same with 22"?

If not, the wheels will spin slower at a certain speed and you are driving faster than your car 'thinks'.

@Andre
Outer diameter is usually very close--as rim is added, rubber is subtracted.

There is usually not much rubber to be substracted at the 21" tesla/wheels, so the diameter must be larger with 22" wheels.

Reduced economy is probably an effect of significantly increased rotational inertia, due to wheels larger diameter.
As mentioned before, the distance travelled per rotation is more, suggestion lesser distance travelled to the car, meaning higher per mile power usage indicated.

jponikau,

If you are right, OP must be aware of speed traps. The car will indicate a lower speed.

Diameter of 21" rim with 35 series rubber is 27.8 inches.
Diameter of 22" rim with 30 series rubber is 27.8 inches.
Circumference of 22" tire vs 21" tire is 0.2 inches greater or a 1 percent difference.
Let's not get carried away with conjecture.

Sorry should have been 0.22% difference between 21 and 22 inch circumferences.

You should update your original post to reflect the fact that it is likely the TEMPERATURE and not the wheels that explains the increase in energy usage. I went from wide 21" to narrower 20" tires for winter setup and my energy increase was about the same as yours due solely to it being colder and the car having to heat up the battery.

Yep, you are right, the 22' step down to 30 ratio, making the total diameter similar. So the only thing explaining the higher energy consumption, besides the colder weather, would be heavier after market wheels and shifting the weight further to the outside of the wheel, both increasing the rotational inertia. But it would not explain a 20% increase in energy consumption.

The speedometer reads so accurate I assume it must be GPS based. Anyone know.

@Roamer
Not GPS based, though rumored to be GPS calibrated.

Looks like it's the weather indeed. I'm back to 320s-340s Wh/mi with 60-70 degree weather here in Houston. (55F today with 352 avg). Thanks to all who kept me from loosing my #TeslaGrin :-)

The 19's have a lot of advantages compared to the 21's.

1) Price. There is a 4500 markup to go from 19 to 21

2) Range. I have heard an extra 8-10 miles of range per full charge.

3) Ride. The consensus on this forum is that the ride is quieter and smoother with the 19's.

4) Tire Wear. My 21's wore down to the belts in just 10K miles. The 19's are good for at least twice that.

5) Price(again). Continental Extremecontacts for my 21's were 300 each or 1200 plus mounting and balancing. I got the OE goodyears for 127 each on tirerack.com.

6) Weight. The combined weight of the 21's and tire is 61 pounds. 26lbs for the tire and 35lbs for the wheel. I purchased a set of OZ Ultraleggera HLT's 19inch which weigh 23 lbs. The goodyears weigh 27lbs for a combined weight of 50 lbs. That is a savings of 11 lbs of unsprung weight at each corner.

Based on all my observations, I feel it is actually cost effective to pay the 1800 for a set of new rims as they will pay for themselves in a few tire changes. All the other benefits are all icing on the cake. In addition, they look awesome.

I will post pictures as soon as they are installed. However, here is a link of the wheel. click on the words "view on vehicle" to get a sneak peek.

http://www.tirerack.com/wheels/WheelCloseUpServlet?target=runWheelSearch...

I ran my 21" wheels year-round last year. This winter I put on 19" wheels. Winter consumption is significantly lower this year. Some of this could be attributed to drier roads this year (no snowpack but colder temperatures).

The 19" tires we bought are low rolling resistance tires. They there wasn't a noticable difference in road noise with the new 19" wheels and tires.

I am in Houston and on short trips, the cold weather (40 degrees F vs. normal 70 or 80) increases energy use dramatically - maybe much more than 20%. Once the cabin and battery heats up and I turn off the climate control, it is maybe less usage than normal. Anecdotally, it seems that variations of 20 degrees in temperature causes such a huge difference that any other factors would be immaterial and difficult to observe.

On a separate note, I have 9k miles on my MS and found it driving like an old used up car even after two new back tires at about 3k miles and an alignment at about 6k miles. It turns out that my 21 inch rims are bent - two of them severely and 2 of them mildly. I live downtown and drive on some pretty shitty city streets daily. For the first 6 weeks I had the car, I hit a few curbs - it has a much wider wheel base than the VW EOS I had before.

I got a quote to replace my rims for about $6500 from Tesla today.

I am thinking of getting some aftermarket 20" rims - hopefully the extra inch of rubber will help with the potholes.

I am curious about the lighter rims and efficiency vs. the lighter rims and structural integrity on the potholes. Anyone have any input on this? I do think that on a Tesla, given the regeneration of coasting, heavier parts may have less impact vs. a car that doesn't use regeneration.

Thoughts?


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