Growing efficiency Gap: R2 w/ 21" vs. 20" tire sets

[ksurfier]

Actually sounds quite comparable….though my max speed has been a bit lower than yours.

Current snapshot (especially for the peanut gallery)

After nearly 40,000 accumulated miles, data point in the opposite direction from the expected ranking. Recent R2 discussion also specifically notes that Roamer is currently showing the ATs as more efficient, despite the expectation that the 21” all-season should win.

Stay tuned…or better yet, don’t, save your hard earned money and buy some shitty-ass Pirelli at the advice of others! …might save you $0.005 per mile but cost you $2k to replace every 6-12 months…

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[lordsutch]

As of now, we have a 0.14 kWh/mi gap based on samples of 32 and 30 vehicles, respectively, with about 40,000 miles travelled between them. Any sort of parametric statistical analysis would need more data; at a bare minimum you'd need the per-vehicle standard deviation just to do a difference of means test, much less anything involving statistical controls. All you can really say at the moment is that you would fail to reject the one-tailed null hypothesis that the stock 20s are less than or equally as efficient as the stock 21s... which is not terribly informative.

Ultimately I think unless a huge gap opens up one way or the other, which seems unlikely, for most buyers the questions will be (a) do you plan to do semi-serious off-roading and (b) do you want to spend an extra $1k now in the hopes of saving money or inconvenience getting replacement tires down the road? If the answer to either is yes, get the 20s (or if it's just b, wait for Premium or Standard Long Range).

 

[Tony S]

More recently, a lot of city driving so max of 55 mph with some highway around 70-75 mph. I am on 20s for what it's worth.

This is concerning to me. I have a reservation and live in FL. My Polestar 2, in strictly city driving, is doing 3.1-3.3 mi/kWh in the middle of summer (AC @ 72); at 70 mph I get 2.8-2.9. Wonder what 21” AS tires would do for the R2?
I realize the size/shape of the P2 is more aerodynamicly efficient than the R2 … but still.

 

[tivoboy]

Efficiency took a hit today with over 105ºF weather and the HVAC running hard but this is me thus far.

Seems pretty clear when you were stress testing it and letting Uncle Kyle hooN it around sideways at the track in NC and blowing out tires. ;-).. after that quite a bit of settling around the 3mpk flatline from road tipping home to normal day to day.

 

[Budman]

@Budman, while I’ve come to expect this kind of reaction from a small but vocal group here, I genuinely didn’t think you were part of that crowd. Do you really believe that openly questioning the data, comparing real-world results, and having an honest discussion somehow amounts to making “false claims” or causing people to lose their “hard-earned money”?

That strikes me as a pretty extraordinary leap. Healthy skepticism and challenging assumptions are how we get closer to the truth, not something that should be silenced because the conclusions might be inconvenient.

I’ve always respected and appreciated the content you post, which is exactly why I’m surprised to see you framing an open discussion this way.

I will try to be respectful and constructive in my response.

There are only 30 or so vehicles with either tire in that RivianRoamer data set. That is quite low. The average efficiency number can easily be skewed by just a few outlier data points. A median value would be better but still sketchy give the low number of vehicles and consequential impact of a many variables.

Any attempt at drawing conclusions or identifying trends from such a small dataset would not be accepted in any of the professional engineering environments I've been associated with.

I don't know if a database like this can ever be useful in the absence of environmental and use case data to parse out the data in a meaningful way.

When Jose first but up the tire guide with efficiency data on his RivianTracker website I posted a comment that said: while I appreciate the attempt here the geographic and environmental variables will make it impossible to draw any meaningful results from this data unless there are a large number of vehicles included. I still stand by that statement.

 

[Mos Eisley]

Stay tuned…or better yet, don’t, save your hard earned money and buy some shitty-ass Pirelli at the advice of others! …might save you $0.005 per mile but cost you $2k to replace every 6-12 months…

It's this kind of biased comment that completely invalidates this entire thread. What you've claimed is a dispassionate examination of data is in reality an agenda to discredit one of the brands in the "research".

 

[ksurfier]

I will try to be respectful and constructive in my response.

There are only 30 or so vehicles with either tire in that RivianRoamer data set. That is quite low. The average efficiency number can easily be skewed by just a few outlier data points. A median value would be better but still sketchy give the low number of vehicles and consequential impact of a many variables.

Any attempt at drawing conclusions or identifying trends from such a small dataset would not be accepted in any of the professional engineering environments I've been associated with.

I don't know if a database like this can ever be useful in the absence of environmental and use case data to parse out the data in a meaningful way.

When Jose first but up the tire guide with efficiency data on his RivianTracker website I posted a comment that said: while I appreciate the attempt here the geographic and environmental variables will make it impossible to draw any meaningful results from this data unless there are a large number of vehicles included. I still stand by that statement.

Agree that nobody should treat the RivianRoamer data as a controlled experiment (or definitive proof that one tire is inherently more efficient than the other).

Where I differ is the conclusion that the dataset therefore can’t provide anything meaningful. 30 vehicles is not huge, but it’s also not so small that the aggregate should automatically be dismissed, particularly when the vehicles collectively represent thousands of miles. Outliers are a concern, and seeing the median, distribution, standard deviation, and individual vehicle results would make the comparison more useful.

The environmental and use-case variables are also real, but many of them should introduce noise in both directions rather than systematically favoring one tire. With enough independent observations, those uncontrolled variables increasingly tend to average out.

I think the distinction is between “proving the 20-inch tire is more efficient” and “observing that the expected 21-inch efficiency advantage is not showing up in the available real-world data.” I don’t think the Roamer dataset establishes the former. But when roughly 30 vehicles per group are collectively producing an average result in the opposite direction from what we would expect, I do think the latter is a reasonable observation.

While I agree with your concerns about drawing strong conclusions, I wouldn’t go so far as saying the data are incapable of telling us anything. To me, they’re hypothesis-generating and make a controlled 20” vs. 21” test all the more worthwhile. Maybe you could team up with another owner and make it happen?

 

[Rivian Roamer]

I was half-tempted to pull the tire guide data entirely. Only of those vehicles have even gotten past the 2,500 mile break in period for the tires. If you filter those out, then start looking at speed data, you're left with almost nothing.

The data currently available isn't useful for drawing conclusions from. This is one of the issues of publishing data without education. People are apt to draw in appropriate conclusions from data they may not fully understand.

 

[Dennisis]

Maybe this thread can be locked now?! Do they do that here? Please?

 

[Thebandit]

I was half-tempted to pull the tire guide data entirely. Only of those vehicles have even gotten past the 2,500 mile break in period for the tires. If you filter those out, then start looking at speed data, you're left with almost nothing.

The data currently available isn't useful for drawing conclusions from. This is one of the issues of publishing data without education. People are apt to draw in appropriate conclusions from data they may not fully understand.

Might not be a bad idea to pull it. And then only publish data from vehicles with more than 2000 miles or something. Any time you give people hard numbers, lots of folks will just accept them as truth.

 

[Thebandit]

The bulk of 21” wheels shipped on Gen 1 quads. This is such a dumb conclusion.

This thread is specially about the R2.

 

[ksurfier]

Maybe this thread can be locked now?! Do they do that here? Please?

Why? Is an analysis of the 21” tire for R2 something that should be “locked” or hidden from someone? Seems like a very strange idea/response…

 

[Dennisis]

Why? Is an analysis of the 21” tire for R2 something that should be “locked” or hidden from someone? Seems like a very strange idea/response…

You seem to be the only one finding value in it.

 

[richpike]

You seem to be the only one finding value in it.

I find value in this thread.

And we should absolutely keep it open - I'll happily admit I was wrong if we get to a couple hundred thousand miles of data and the 21s have jumped to their rated delta vs the 20s. Hard to do that in a closed thread. I also hope if the 20s continue to keep an efficiency gap that others will be willing to reconsider their stances too.

-Rich

 

[Rivian Roamer]

I find value in this thread.

And we should absolutely keep it open - I'll happily admit I was wrong if we get to a couple hundred thousand miles of data and the 21s have jumped to their rated delta vs the 20s. Hard to do that in a closed thread. I also hope if the 20s continue to keep an efficiency gap that others will be willing to reconsider their stances too.

-Rich

So far, at 70 MPH the data is aligning closely with what Kyle and Jose tested. Still not significant but I haven't seen anything to say that their test wasn't accurate.

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