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

[richpike]

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.

Sadly they didn't compare the two tires (no complaining - they did a ton of useful analysis). Would have been awesome if they did though. Which is why the best scenario we might get is all of the data you're collecting where we eventually hit an amount that everyone can feel comfortable has removed any outliers.

And maybe I haven't been clear - I don't buy tires for efficiency and don't really care (or I wouldn't be running 20" LT tires on my R1S). It's more just intriguing to me that the 20s are currently doing better than the 21s and the gap doesn't seem to be closing as more and more data rolls in. This makes me wonder if there is potentially something wrong with the 21s. Which isn't far fetched given there is a rumor that Rivian has sued Pirelli on a group of tires for the R1 platform.

-Rich

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[Rivian Roamer]

Sadly they didn't compare the two tires (no complaining - they did a ton of useful analysis). Would have been awesome if they did though. Which is why the best scenario we might get is all of the data you're collecting where we eventually hit an amount that everyone can feel comfortable has removed any outliers.

And maybe I haven't been clear - I don't buy tires for efficiency and don't really care (or I wouldn't be running 20" LT tires on my R1S). It's more just intriguing to me that the 20s are currently doing better than the 21s and the gap doesn't seem to be closing as more and more data rolls in. This makes me wonder if there is potentially something wrong with the 21s. Which isn't far fetched given there is a rumor that Rivian has sued Pirelli on a group of tires for the R1 platform.

-Rich

Looking at the small sample size of 70 MPH segments on RR. The AS are indeed more efficient at 70 MPH but the gap isn't very large at all.

I suspect the 21" wheel design is impacting aero a decent amount.

 

[Thebandit]

Sadly they didn't compare the two tires (no complaining - they did a ton of useful analysis). Would have been awesome if they did though. Which is why the best scenario we might get is all of the data you're collecting where we eventually hit an amount that everyone can feel comfortable has removed any outliers.

And maybe I haven't been clear - I don't buy tires for efficiency and don't really care (or I wouldn't be running 20" LT tires on my R1S). It's more just intriguing to me that the 20s are currently doing better than the 21s and the gap doesn't seem to be closing as more and more data rolls in. This makes me wonder if there is potentially something wrong with the 21s. Which isn't far fetched given there is a rumor that Rivian has sued Pirelli on a group of tires for the R1 platform.

-Rich

It is closing actually. It was 0.18 at the beginning of the thread and now it's 0.14.

 

[richpike]

I suspect the 21" wheel design is impacting aero a decent amount.

That's an intriguing thought.

-Rich

 

[richpike]

It is closing actually. It was 0.18 at the beginning of the thread and now it's 0.14.

I seem to recall it started at 0.15. Went to 0.18. And now is at 0.14. So it hasn't changed much from the first time it was reported on Rivian Roamer (IIRC).

-Rich

Edit: I thought I'd saved a screenshot of when I first saw it, but can't find it, so that could be wrong.

 

[Dennisis]

Is it possible the Rivian engineers, with their expertise and resources, actually determined the appropriate values for these? Just saying and now I’ll stay out of it but isn’t that the most likely answer? No offense but the idea any of you have more knowledge seems unlikely.

 

[Rivian Roamer]

Is it possible the Rivian engineers, with their expertise and resources, actually determined the appropriate values for these? Just saying and now I’ll stay out of it but isn’t that the most likely answer? No offense but the idea any of you have more knowledge seems unlikely.

Which values?

 

[richpike]

Is it possible the Rivian engineers, with their expertise and resources, actually determined the appropriate values for these? Just saying and now I’ll stay out of it but isn’t that the most likely answer? No offense but the idea any of you have more knowledge seems unlikely.

Like they did with the Gen1 sub-frame? Or the gen1 mobile-eye that was supposed to enable L4? The Rivian engineers are amazing - absolutely love our Gen1. But sometimes things happen that they didn’t expect. Or a supplier doesn’t follow through with what they claimed.

-Rich

 

[Dark-Fx]

Like they did with the Gen1 sub-frame? Or the gen1 mobile-eye that was supposed to enable L4? The Rivian engineers are amazing - absolutely love our Gen1. But sometimes things happen that they didn’t expect. Or a supplier doesn’t follow through with what they claimed.

-Rich

Don't know why you'd use examples from back before they had expertise.

 

[richpike]

Don't know why you'd use examples from back before they had expertise.

I’m confused - you think they knew nothing when they started? How about the R2 where they’ve already revised the headrest? Engineers aren’t infallible.

-Rich

 

[Dark-Fx]

I’m confused - you think they knew nothing when they started? How about the R2 where they’ve already revised the headrest? Engineers aren’t infallible.

-Rich

You're definitely confused, I'll give you that.

 

[richpike]

You're definitely confused, I'll give you that.

I give you multiple examples where Rivian’s initial design didn’t work out. Some their fault. Some (likely) their supplier’s fault. But I’m the one who is confused?

-Rich

 

[Mos Eisley]

Looking at the small sample size of 70 MPH segments on RR. The AS are indeed more efficient at 70 MPH but the gap isn't very large at all.

I suspect the 21" wheel design is impacting aero a decent amount.

Which is what Jeff at Rivian has said from the beginning - plus the AT tire itself (compound and weight) dings range vs the 21".

 

[jrmbadger]

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

Speak, for yourself. I find value in the thread. I'm interested in the data and the legitimate discussion, even though I'm not jumping to conclusions on what its saying.

 

[Rivian Roamer]

Which is what Jeff at Rivian has said from the beginning - plus the AT tire itself (compound and weight) dings range vs the 21".

I suspect two things.

1. The 21" wheel design is just not aero efficient
2. The 20" ATs are more for highway and not real ATs

The range difference between them is really small at 70 MPH. Yeah you'll take a hit but not as much as you'd think compared to R1. I doubt as many people are going to "touch dirt" with their R2 compared to R1.

Range estimates will be more accurate on the ATs over AS. Seems like Rivian really pushed the range estimates with the AS to "beat" the Model Y on paper.

That is to say you'll see closer to stated range with the ATs over AS.

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