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

[Hilikus]

Meanwhile, you‘d be driving on these crappy, sloppy, noisy AT tires on asphalt for the duration. For some people quantity IS quality.

I'd be coming from Nokian Outpost APT on one Honda, Michelin Cross Climates on the other Honda, and Nokian Outpost AT on the Jeep. I think I can live with it on the 20s till they wear out. I didn't notice any noise at all on my test drive with the 20s since it was so quiet compared to what I'm used to.

Hopefully they drown out the noise of slush hitting the under carriage and wheel wells during the 6 months of winter we usually get. Or the noise of chip sealant for the 6 months of construction we get when it's not winter.

Sponsored

 

[derekmw]

I had to do a mostly freeway drive in our new R2, driving 45 min away. At first I set cruise control at 80, and I was only getting 2.0mi/kwh which is worse than my R1T was on 20" AT. Then I lowered the speed to 70, and ended up with 3.5mi/kwh. It's not any kind of accurate test but at least it shows you the drastic change between 70mph vs 80mph. I'm going to keep monitoring it...it is pretty crazy that it got such a low mi/kwh at 80...I would have expected at least similar to my R1T did, but then I guess that one went into low mode to conserve energy.

 

[cwq93r]

Also, check your tire pressures. My 21” tires have been showing 38psi since delivery day. I kept hearing 42psi on YouTube, so I checked my door. After setting them correctly, I expect I’ll see an increase in my efficiency.

 

[dub]

My commute to work is 30 miles and it's almost evenly split between surface roads and freeway. Going 75 for the freeway stretch I got about 2.9 mi/k. Going 70 on the freeway today it was 3.3.

Speed seems to make an even bigger difference on R2 than it did on R1 when it comes to efficiency. In both R1 that I had, 5mph typically resulted in .1 mi/k difference.

*this is on brand new 20s, so assume some reduced efficiency

Different vehicles have different drag coefficients, but eventually drag is the dominant factor affecting efficiency. Sounds like dropping lower really helps the R1.

If your numbers held up in a controlled test for the R2, it sounds like it has become dominant at 70 mph. For example, I'd expect you to get 3/4 the range at 80mph than at 70 mph.

 

[Eric9610]

Perhaps, perhaps not. The 20” rim
Is forged, the 21” rim is cast. Would much rather have the durability of a forged rim (and the more durable tire). Can always replace with AS if the ATs get too noisy; though they are surprisingly quiet when new.

I don’t know where you got this info but it’s incorrect. The 21s and 20s are both forged. It’s stated on the Rivian site.

 

[ksurfier]

Gap is closing a bit….

(https://rivianroamer.com/guides/tire-efficiency?platform=r2)

 

[DaveA]

I can't say I noticed much of a noise difference between the two, which seems to be the case for most from what I've read here.

Seems the 20" AT tire is much closer to an All Season design vs a true All Terrain.

This seems even more true based on the real world data showing it's has very similar efficiency compared to the 21" Pirellis.

But to each their own!

The Pirellis, after break in of a few thousand miles (just like the Pirellis on the R1T), will overtake the 20s in efficiency. I regularly see 3.30 or higher on highway at 70 mph.

 

[ksurfier]

The Pirellis, after break in of a few thousand miles (just like the Pirellis on the R1T), will overtake the 20s in efficiency. I regularly see 3.30 or higher on highway at 70 mph.

What’s your current average, significantly higher than 2.7 MPK?

 

[DaveA]

What’s your current average, significantly higher than 2.7 MPK?

I'm just reporting what the efficiency meter shows during 15 minutes plus of any highway driving at 70 mph. I'm not sure what the average is at the moment, but its not 3.30 with my short drives to work.

 

[windshieldfarmer]

I don’t know where you got this info but it’s incorrect. The 21s and 20s are both forged. It’s stated on the Rivian site.

I received this information from a representative at the Denver SC when I did my test drive. He specifically shared the the 20” was forged and the 21” was not. That said I just did an AI search and appears I was misinformed; both wheels are indeed forged.

 

[savethemanual]

I received this information from a representative at the Denver SC when I did my test drive. He specifically shared the the 20” was forged and the 21” was not. That said I just did an AI search and appears I was misinformed; both wheels are indeed forged.

The world we live in nowadays, so much misinformation out there. There's been technical info incorrect on Rivian's own site before so they don't always get it right either.

 

[windshieldfarmer]

The world we live in nowadays, so much misinformation out there. There's been technical info incorrect on Rivian's own site before so they don't always get it right either.

The thing that is especially irritating to me is that I made a purchasing decision to acquire the 20” wheels, in part because I thought they would be less prone to impact damage compared to the 21s. I still would probably purchased the 20s but….geez.

 

[ksurfier]

I'm just reporting what the efficiency meter shows during 15 minutes plus of any highway driving at 70 mph. I'm not sure what the average is at the moment, but its not 3.30 with my short drives to work.

I'm just reporting what the efficiency meter shows during 15 minutes plus of any highway driving at 70 mph. I'm not sure what the average is at the moment, but its not 3.30 with my short drives to work.

Something seems off, we get long range 70 mph testing that return ~2.7 MPK, but then there are apparent outliers of 3.3 MPK…I think the Model Y is prob. ~3.4-3.5 MPK at 70 mph…
This is a big difference, 290 miles range at 70 mph or less than 240 miles…my own tests have yielded the following:

• 70 mph: 2.73 mi/kWh (240 miles)
• 72 mph: 2.60 mi/kWh (229 miles)
• 76 mph: 2.50 mi/kWh (220 miles)

 

[ksurfier]

Update: The R2 efficiency data are becoming increasingly consistent across two independent lines of evidence. The Rivian Roamer fleet now includes 93 vehicles and more than 61,000 miles, with the 20-inch BFG group averaging 2.75 mi/kWh versus 2.68 mi/kWh for the 21-inch Pirelli group, a roughly 2.6% advantage for the 20s. Separately, the available long-range highway tests near 70 mph have also generally shown the 20-inch setup about 2% to 3% more efficient. The notable point is that these two datasets differ substantially in how they were collected, yet they are converging on nearly the same result.

Statistically, we still cannot calculate a definitive pooled p-value without the underlying vehicle-level variance, but the agreement in both direction and magnitude makes random sampling variation a less likely explanation. My current best estimate is that the true real-world efficiency advantage of the 20-inch setup is about 2% to 3%, with roughly 2.5% as the most likely value. If the Roamer dataset continues to grow while maintaining even a 2% advantage, the case that the 20-inch configuration is genuinely more efficient in real-world highway driving will become increasingly difficult to dismiss.

 

[mkhuffman]

Update: The R2 efficiency data are becoming increasingly consistent across two independent lines of evidence. The Rivian Roamer fleet now includes 93 vehicles and more than 61,000 miles, with the 20-inch BFG group averaging 2.75 mi/kWh versus 2.68 mi/kWh for the 21-inch Pirelli group, a roughly 2.6% advantage for the 20s. Separately, the available long-range highway tests near 70 mph have also generally shown the 20-inch setup about 2% to 3% more efficient. The notable point is that these two datasets differ substantially in how they were collected, yet they are converging on nearly the same result.

Statistically, we still cannot calculate a definitive pooled p-value without the underlying vehicle-level variance, but the agreement in both direction and magnitude makes random sampling variation a less likely explanation. My current best estimate is that the true real-world efficiency advantage of the 20-inch setup is about 2% to 3%, with roughly 2.5% as the most likely value. If the Roamer dataset continues to grow while maintaining even a 2% advantage, the case that the 20-inch configuration is genuinely more efficient in real-world highway driving will become increasingly difficult to dismiss.

Your AI bot is wrong.

Sponsored