Information or reasoned speculation on range with AT 20's and 'Conserve' mode - please avoid drift

[DB-EV]

Hey everyone!

I am very excited for the the launch, and for the first time in months (years?) I believe I could get my launch edition R1s by year end 2021. Ordered Spring 2019, live about 20 miles from one of the four service centers, and have a configuration that I believe will keep me near front of line.

My question for this helpful group of folks: What do we know (or believe based on a combo of reasoning and speculation) about the combination of the AT tires and 'Conserve' mode? I read through the EPA posts, but as usual (and understandable) - a lot of thread drift makes it hard to get what I am looking for. (PS this community is amazing - this is not a normative judgment by me - just my belief; positives of this place outweigh the negatives). It also seems that the Motor Trend review implied, if not stated, that the ATs in conserve could hit 301 (they tested on ATs).

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Why do I ask? Nothing will change my support for Rivian's concept, but I was surprised by the stated 10-15% hit on 316 miles for ATs. One of the things I want to use my R1s for is winter trips to the mountains, which is about 200 highway miles away, almost no local driving. I had thought based on all the info out there that the goal was to hit 300 miles with the ATs. I even ditched the offroad upgrade before the air compressor was included because I saw info leaking about how that upgrade would hit the mileage. Add in winter / cold weather degradation and what could be lower mileage (rather, even lower mileage than I thought) with the ATs, you can see my concerns. There are already at least some open high speed chargers on the route (thank you, VW, I guess?) and Rivian's map includes helpful locations.

I don't see the 400 mi/enhanced R1s pack as viable for me: I just don't see the economic incentive for Rivian to make these (battery constraint plus only 10k premium when the increase equals about 1/3 of a vehicle's battery need), and things have changed enough that I don't want to make a leap of faith.

I also understand how much engineering went into even hitting these numbers; While I am disappointed by the AT range, I am a firm believer in physics (which doesn't 'care' if I believe in it or not). I very much respect what Rivian has done to get here; whether or not I stay with the res, I will always be fanning on Rivian.

THANKS!

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[nfrank]

My primary reason for getting the 20s is because the 21s are a custom tire size. The secondary reason is because more sidewall reduces curb rash. The tertiary reason is all season traction.

That said, all 20” tires available today are 10-ply LT grade. This is a heavier tire and overkill for the Rivian’s GVWR. Some off-road drivers may appreciate this, but not me.

It would be great if a tire maker offered a regular passenger grade tire with all-season tread. If that were ever an option, I could see the 20” wheels with better range then the 21s.

 

[Attesan997]

Don’t think there’s much evidence to suggest conserve mode will provide enough improvement to get 300 miles on the ATs. Technically I guess there’s no evidence to say it won’t but it’s unlikely any more will be known until these start getting delivered and tested in the real world. For all anyone knows Rivian is being extremely conservative with the EPA rating.

 

[Zoidz]

I am a firm believer in physics (which doesn't 'care' if I believe in it or not).

I wish more people accepted this!!!

Unfortunately, any detailed discussion about "Conserve" mode is speculation. AFAIK, the only thing we know about it was stated in the "Motor Trend" review - it is a "Front Wheel Drive" mode. I don't know of anything officially released by Rivian....

 

[Pugster]

Following this thread.

There was a suggestion that the EPA rating was done in blend of all modes, which would include some that are more energy hungry (such as sport and off-road, rock crawl, etc.). I’m hoping that the real world numbers run in the more efficient modes give us 20” A/T fans a bump. I do suspect we will continue to see 10-15% reductions compared to all season tires however. On my Model 3 tire choice can have a pretty big impact on range.

 

[DucRider]

There was a suggestion that the EPA rating was done in blend of all modes, which would include some that are more energy hungry (such as sport and off-road, rock crawl, etc.).

There is no provision to do this in the EPA test procedures - it must be tested in a single mode. The most Rivian could have done is test in one of the more efficient modes and then done a "Voluntary Reduction" for the official label number. This reduction is noted in the EPA info and is not present for the Rivian.
I believe that this "tested in a blend of all modes" nugget came form a CS rep and likely came from their internal testing and not the official EPA test. CS statements have always been a mixed bag of accuracy - asking 3 reps the same question will often get 3 answers that differ to at least some degree.

 

[Pugster]

There is no provision to do this in the EPA test procedures - it must be tested in a single mode. The most Rivian could have done is test in one of the more efficient modes and then done a "Voluntary Reduction" for the official label number. This reduction is noted in the EPA info and is not present for the Rivian.
I believe that this "tested in a blend of all modes" nugget came form a CS rep and likely came from their internal testing and not the official EPA test. CS statements have always been a mixed bag of accuracy - asking 3 reps the same question will often get 3 answers that differ to at least some degree.

Makes a lot of sense. Standardization would be very difficult if they used a blended version. So the question is…what mode did they use, and will “conserve” eke any more range out of the A/Ts….?‍

 

[DucRider]

Makes a lot of sense. Standardization would be very difficult if they used a blended version. So the question is…what mode did they use, and will “conserve” eke any more range out of the A/Ts….?‍

If range is that much of a concern - slow down.
Going even a few mph slower at freeway speeds will have much more impact than any "Conserve mode".

People that are hoping to get back most or all of the range penalty from the 20s are going to be dissapointed.

 

[ajdelange]

My question for this helpful group of folks: What do we know (or believe based on a combo of reasoning and speculation) about the combination of the AT tires and 'Conserve' mode?

As we know nothing about "conserve mode" the answer has to be "nothing". There probably will be a conserve mode but it will probably do pretty trivial things such as limit acceleration, turn off unnecessary lights, limit how much the HVAC system can be used, turn off the AC outlets and things like that.

As for changing tires: all we can say is that if the tire and or wheel are different from what was mounted when the EPA test was done the range will be different from what the EPA test determined and that is always different from what one experiences on the road. The observed differences will probably be biased in what you will consider an unfavorable direction. A tire that is not optimized for paved roads is likely to have a higher rolling resistance coefficient than one that is.

 

[SeaGeo]

Let's just see what people get when the first trucks get out in the public. We know InsideEVs will be involved with the first open media days, and trucks will start hitting customers soon. Luckily the absolute vast majority of us have plenty of time to learn from the experience of others.

 

[Condor]

I’m not a fan of the 21” wheel because I don’t like the wheel itself or that it is a unique size. So what if I got the 22” wheel and changed to tire to a higher aspect ratio? Let’s say I picked a 275/55-65/R22. How would that impact range?

 

[Condor]

Never mind, it looks like no such tire exists

 

[Gamma rays]

My primary reason for getting the 20s is because the 21s are a custom tire size......

That's my concern as well. I don't want to get stuck with paying expensive replacements down the road. This choice is now made more difficult with decrease in range if I opt for the 20".

GR

 

[YamaLink]

Terrific thread/question. I believe it will be coming back in searches and be the deciding factor for many, many deposit refunds. Likin' that truth: physics doesn't care what I think. Reminds me of the saying "you're entitled to your own opinions, not your own facts."

20" AT in cold weather is a big handicap. Much like the F150 Lightning's range when towing (pretty much nonexistent). It's a dealbreaker for the target demographic.

 

[Greenwater]

Hey everyone!

I am very excited for the the launch, and for the first time in months (years?) I believe I could get my launch edition R1s by year end 2021. Ordered Spring 2019, live about 20 miles from one of the four service centers, and have a configuration that I believe will keep me near front of line.
...
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Why do I ask? Nothing will change my support for Rivian's concept, but I was surprised by the stated 10-15% hit on 316 miles for ATs. ...

I've been driving a tesla model s since 2013 and based on my experience, it doesn't make sense to sweat 15% range loss. The variations of temp., speed, driving aggressiveness (acceleration), weather (rain/wind) far outweigh 10-15% range loss. If you are driving a route that you can't do with 10 or 15% range loss you will get stuck at some point. You will be playing with running out of power if you run it down to the wire that much. The lowest I've gone down to was 6km once, that was scary on a rainy stormy night going to whistler.

There's a weird tesla saying, drive slower to get there faster. Slower is more efficient, so you need less recharging stops. Sometimes driving slower is really faster.

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