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

[Rivian2026]

I love this thread, and this is the first time I have chimed in. I am not sure of the motives of ktsurfer, but I appreciate the discussion nonetheless. And I appreciate hearing people push back (respectfully and as adults) and put the Rivian Roamer data in perspective.

(Ktsurfer, I like that you started these threads. And I don't mind your use of AI. I take it all with a grain of salt. But I do wonder sometimes if you're the Tesla owner punking all of us or are trying to drive up Rivian revenue or drive business to BFG. It's kinda irrelevant though - it's an interesting topic. This isn't work or serious for me - just a fun distraction.)

Getting back to the main point, I still don't know which tires to get! I do care about efficiency, but my sense (you can tell me I am wrong) is that there are not huge differences in efficiency, even if the 21s are better. I am thinking longer term though and wondering what wheel size I am going to like the most if, for example, I swap out AT tires on the 20" with all season tires (since I am in Boston and drive to Maine a lot during the winter - I need something that is good in snow). The comments that the 20" inch tires, with more sidewall, are going to be more comfortable are pushing me in that direction. If the AT tires are loud, then I can get a replacement all season tire that has the bigger sidewall and has less road noise. Thoughts?

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[ksurfier]

I love this thread, and this is the first time I have chimed in. I am not sure of the motives of ktsurfer, but I appreciate the discussion nonetheless. And I appreciate hearing people push back (respectfully and as adults) and put the Rivian Roamer data in perspective.

(Ktsurfer, I like that you started these threads. And I don't mind your use of AI. I take it all with a grain of salt. But I do wonder sometimes if you're the Tesla owner punking all of us or are trying to drive up Rivian revenue or drive business to BFG. It's kinda irrelevant though - it's an interesting topic. This isn't work or serious for me - just a fun distraction.)

Getting back to the main point, I still don't know which tires to get! I do care about efficiency, but my sense (you can tell me I am wrong) is that there are not huge differences in efficiency, even if the 21s are better. I am thinking longer term though and wondering what wheel size I am going to like the most if, for example, I swap out AT tires on the 20" with all season tires (since I am in Boston and drive to Maine a lot during the winter - I need something that is good in snow). The comments that the 20" inch tires, with more sidewall, are going to be more comfortable are pushing me in that direction. If the AT tires are loud, then I can get a replacement all season tire that has the bigger sidewall and has less road noise. Thoughts?

You essentially have three options:

1. 20s: the easy button. Good tire availability, including winter options, with no need to overthink it.

2. 21s + dedicated winter setup: keep the 21s for summer, then buy aftermarket 18”, 19”, or 20” wheels with a proper winter tire or strong all-season.

3. 21s year-round: see how they do this winter and hope more tire options come to market.

For me, even though I really like the 20” setup, if winter driving were a regular consideration, I’d probably get the 21s and build a dedicated winter wheel/tire setup. That gives you the best of both worlds. But that is $3k additional instead of $1k…

 

[txaggies07]

I love this thread, and this is the first time I have chimed in. I am not sure of the motives of ktsurfer, but I appreciate the discussion nonetheless. And I appreciate hearing people push back (respectfully and as adults) and put the Rivian Roamer data in perspective.

(Ktsurfer, I like that you started these threads. And I don't mind your use of AI. I take it all with a grain of salt. But I do wonder sometimes if you're the Tesla owner punking all of us or are trying to drive up Rivian revenue or drive business to BFG. It's kinda irrelevant though - it's an interesting topic. This isn't work or serious for me - just a fun distraction.)

Getting back to the main point, I still don't know which tires to get! I do care about efficiency, but my sense (you can tell me I am wrong) is that there are not huge differences in efficiency, even if the 21s are better. I am thinking longer term though and wondering what wheel size I am going to like the most if, for example, I swap out AT tires on the 20" with all season tires (since I am in Boston and drive to Maine a lot during the winter - I need something that is good in snow). The comments that the 20" inch tires, with more sidewall, are going to be more comfortable are pushing me in that direction. If the AT tires are loud, then I can get a replacement all season tire that has the bigger sidewall and has less road noise. Thoughts?

Great post. I think most of us in this thread are genuinely curious and would love to have some good answers on the true real-world performance of these tires.

I also don't mind (in general) the use of AI. I use it every day extensively for my work. However, I still have to inspect the work the AI does before I submit my completed deliverables. It does a great job, but sometimes the prompts need to be refined and it can draw some silly conclusions. My issue with AI here is that I think the data needs more inspection. It is easier to write better prompts when you understand the data analysis that needs to happen. Instead of asking AI a simple, analyze this data, it needs to be asked a prompt with detailed analysis instructions.

I am on the fence on wheels/tires. I think I like the look of the 20" better. I like the idea of more tire availability. However, they are $1000 so it takes time to work off that cost debt with new tires. You can't just say $450 a tire x 4. It is the delta in costs per tire, so more like $150 x 4.

Anyways, happy to see where the data lands when there are a few million miles. I dont think we have enough data at this point to show one way or another.

 

[ksurfier]

In other news, August’s two longest R2 drives reached 244.2 and 238.6 miles, both using roughly 90% of the battery and averaging nearly identical 2.90–2.91 mi/kWh despite different routes and conditions.

That implies roughly 265–271 miles on a simple 100% extrapolation, although OOS reported the final 10% depleted noticeably faster. Taken together, these results appear to agree well with the OOS/RivianTracker July test and further support the emerging ~250-mile R2 at normal interstate speeds picture.

 

[Dave Cundiff]

Regarding whether or not to belabor a point, here's another relevant quote, this one from Abraham Lincoln [emphasis added]:

“Die when I may, I want it said of me by those who knew me best, that I always plucked a thistle and planted a flower where I thought a flower would grow.”

https://www.goodreads.com/quotes/17326-die-when-i-may-i-want-it-said-of-me

Best to all!

 

[tivoboy]

Could we at least at this point change the title of this thread to

”no longer growing efficiency gap between the R2 20’ and 21’ tires”

 

[ksurfier]

Could we at least at this point change the title of this thread to

”no longer growing efficiency gap between the R2 20’ and 21’ tires”

The AI bots told me no we can’t, but I’ll check back in with them in a week or two!

 

[Thebandit]

Dave, your neutral/friendly demeanor is appreciated.

For a few of the others, I totally get it. When you can’t make much headway attacking the data, eventually it gets tempting to attack the person instead.

Apparently I’m an “AI bot,” my analysis is bogus, my polls are “stupid,” I “don’t actually want discourse,” and debating me is supposedly the equivalent of debating a machine. At one point Dave actually had to jump in and ask that the discussion stick to my arguments and conclusions rather than “insinuations and personal attacks.”

And this isn’t exactly an isolated bad afternoon.

Mkhuffman, for example, has repeatedly gone beyond saying he thinks my analysis is wrong. He’s called me an “AI bot,” said debating me is basically debating a bot, and dismissed a poll I posted with a standalone “This is stupid.” That same style shows up elsewhere too. He’s told another member to “move on and shut your pie hole,” called someone a “goober,” described their explanation as “idiotic,” and in another thread questioned whether an OP was even a real person or had a “comprehension issue.” At some point that stops looking like vigorous disagreement and starts looking more like a fairly consistent way of dealing with people he strongly disagrees with.

Jeremy has gotten into similar territory. Saying I “don’t actually want discourse” is already assigning a motive rather than arguing the substance. Following that with “Doubling down, very impressive AI bot” pretty clearly isn’t a technical critique either.

Have I thrown a few elbows back? Of course. I’m not going to pretend I’ve responded to every jab with perfect restraint. It’s an internet forum, people get a little spicy, and I’m certainly not above the occasional smart-ass response.

But there’s a difference between trading a little snark and making the person the argument.

If you think my numbers are wrong, great, show me where. If there’s a bad datapoint, point it out. If I normalized something incorrectly, explain why. If the regression doesn’t hold up, tear it apart. Better yet, bring more data.

That’s actually useful.

And contrary to the idea that I’ve somehow planted a flag and refuse to move, I’ve changed my position several times as the dataset improved. Some of the things I was fairly convinced of a few months ago I’d qualify considerably today. That’s what should happen when more evidence comes in.

What gets tiresome is when the conversation moves from “I think your analysis is wrong” to questioning intelligence, motives, authenticity, posting habits, whether I’m a real person, or whatever variation of “AI bot” we’re up to this week.

None of that tells us whether an R2 gets 2.7 or 3.0 mi/kWh at 70 mph.

And disagreement itself really doesn’t bother me. Some of the most useful information in these threads has come from people challenging something I posted. A good counterargument makes the analysis better. A new datapoint makes the dataset better. Someone finding an error is useful because then it can be corrected.

So challenge the methodology. Question the assumptions. Find holes in the dataset. Tell me I’m wrong and explain why. Fair game.

But calling someone an “AI bot” for the 14th time isn’t exactly peer review.

Eventually it’s just heckling with a keyboard.

Unfortunately for all of us, the spreadsheet remains completely indifferent to personal insults.

However today was eye opening, the censorship and Riv-bros mentality that thrives in this forum wasn’t something expected….sad

The idea that you're an AI bot is the most flattering thing anyone here thinks about your ridiculous crusade.

 

[mkhuffman]

You essentially have three options:

1. 20s: the easy button. Good tire availability, including winter options, with no need to overthink it.

2. 21s + dedicated winter setup: keep the 21s for summer, then buy aftermarket 18”, 19”, or 20” wheels with a proper winter tire or strong all-season.

3. 21s year-round: see how they do this winter and hope more tire options come to market.

For me, even though I really like the 20” setup, if winter driving were a regular consideration, I’d probably get the 21s and build a dedicated winter wheel/tire setup. That gives you the best of both worlds. But that is $3k additional instead of $1k…

If the R2 21s perform as well as the Pirelli 22s on my truck, I think the 21s will be fine in snow. While not snow rated they easily handled fairly deep and icy snow this past winter.

I did donuts and ended up damaging the front of my truck after intentionally running over snow banks. So much fun, but next time I will be more responsible. The damage wasn't cheap.

 

[Husky]

We live in a very hilly part of NH, we get lots of snow, and our house is at the top of a 950' hill. For the past 20 years, since we've been driving AWD vehicles, I've only put AS tires on our year-round cars and have never had a problem or wished that I had dedicated snows on. I'm glad the days of needing snows on dedicated wheels are behind me.

 

[en56]

Imagine being more toxic than fucking reddit. That's some some work.

I TOTALLY hear you .

Maybe it’s just me , but I’ve actually been finding the Reddit R2 forum less toxic than the rivianforums R2 space. It’s got less technical depth . But maybe that results in less hackles going up? Perhaps I just haven’t been going deep into the reply’s on the Reddit r2 threads

At the end of the day we are all just talking about whether or not 120mpge vs 90mpge is going to work for someone . What a time to be alive . We all get to zoom around on the energy density equivalent of 2.5 to 3 gallons of gas’s for hundreds of miles !

 

[asellus]

lol you got a thread locked without making it past 1 page.

I suspect many feel this thread should be locked too.

yeah, reporting his posts as "this is AI generated junk" seems to work? turns out the mods do care!

 

[Eric9610]

None of this discussion matters in California now that the CEC passed the OEM tire rule. No matter what size you go with you won't be able to get non OEM options..

LOL

 

[ksurfier]

None of this discussion matters in California now that the CEC passed the OEM tire rule. No matter what size you go with you won't be able to get non OEM options..

LOL

It’s okay, we have a clear path forward:

All the refineries leave California, and you can only put OEM tires on your non-moving vehicle.

Environmentalist win-win!

 

[stewmander]

None of this discussion matters in California now that the CEC passed the OEM tire rule. No matter what size you go with you won't be able to get non OEM options..

LOL

That makes this discussion even more pertinent to wheel choice: there is 1 OEM 21" tire offered, and 2 OEM 20" tires offered. You can switch from the BFGs to the Pirellis even with the new rule.

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