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

[ajdelange]

The thing about range is that you don't need a lot of it except when you do. One of the two factors limiting wider, faster BEV adoption is the lack of charging infrastructure which is used for only perhaps 15% of charging (85% is done at home).

The R1T Large is to have 316 miles EPA range. That is plenty. My first BEV had less than that (294) and I was fine with it. But then the practical range of the R1T isn't 316 miles. The prudent driver will stay out of the upper 10 and lower 10% of the battery range if at all possible. One of these special tires/wheels will cost another 15% reducing working range to (100 - 20 - 15) = 65% of 316 miles which is 205 miles. Now add on a percent per year battery aging loss, several % for the wind and the rain etc. and you might want to think seriously about giving up 10 - 15% for wheels that look nicer. Most of the time it won't matter, of course but when it does it does.

My thinking on this is colored by spending part of last week in an area with sparse DCFC opportunities. I would not willingly have given up 30 - 45 miles range. I have never before been in a situation where I had to be so cognizant of what was in the battery and where the nearest SC was.

In the end it always seems to come back to the admonition to get the biggest battery you are comfortable paying for. We were in a 350 mile Tesla. The 400 mi R1T would have added some additional comfort zone.

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[sub]

I would not buy the vehicle assuming there will be a mode that will make the vehicle so much more efficient that it can offset the 45 miles of range that you are loosing with the 20 inch all terrain tires. I doubt that it is possible (perhaps 1-2%, but not anything close to 10-15%), and I also doubt that Rivian would have not used every trick up their sleeve on the EPA test.

If you hate the 21-in wheels, but don't want to lose 15% of your range with the 20 inch all terrain tires. You can buy the 20-in wheels and replace the tires with low rolling resistance 275/60 R20 road tires (smaller diameter than the AT tires, the same diameter as the oem 21/22 tires).

275/60 R20 is a very common size, there are a ton of options and you will have no problem finding replacement in the event of a flat. You will still have less range than the 21-in option because the 21's are a more aerodynamic shape, but I suspect it would get you up over the 300 mile mark.

Yes, tossing out brand new tires is annoying, but Silver 20's + a new set if tires will still be cheaper than the black 20's. And you may be able to sell the OEM tires to recoup some of the cost.

 

[twinprice]

Tire rack now lists the 21” tires and says there are 4 available for $383.75 each. Even says “Rivian RIV” underneath style

https://m.tirerack.com/tires/tires....R1SVASXL&vehicleSearch=false&fromCompare1=yes

 

[CommodoreAmiga]

Tire rack now lists the 21” tires and says there are 4 available for $383.75 each. Even says “Rivian RIV” underneath style

https://m.tirerack.com/tires/tires....R1SVASXL&vehicleSearch=false&fromCompare1=yes

I'm curious to learn what the UTQG rating is. I estimate replacing the 21" tires will cost approximately $400-500 more than the 20" tires. At $1,800 for the wheel upgrade to 20" and an extra $200 for the spare tire, it would take 4-5 sets of tires before breaking even. Depending on how many miles each set lasts, that may be a rather long break-even point -- especially considering the increased efficiency of the 21".

Tough choices.

 

[Sean]

One thought on the 2wd highway, could be that the all purpose mode can detect and switch automatically. If that's already present then no big bump coming if a conserve mode is released.

 

[DB-EV]

One thought on the 2wd highway, could be that the all purpose mode can detect and switch automatically. If that's already present then no big bump coming if a conserve mode is released.

Guys - the Motortrend Part 2 Trans America Trail video shows them at minute 9 switching through modes on the ATs; Conserve mode takes them up to 308 on the AT's. Hopefully helpful - not sure if posted elsewhere.

Also, I have an email into customer service asking what range is (expected to be) in conserve with ATs given that the manual refers to the mode. When I last contacted them, conserve was not publicly acknowledged. Will post what I get. (A second question for any soft (east cost) sand drivers is whether Rally mode is best for soft sand).

Please LMK if you know more. Best, D.

 

[Trekkie]

If conserve mode is anything like range mode in our Model X it'll limit the heating/cooling of the cabin to about the middle of the speed and it'll slow down your 0-60 punch it time as well.

And not change the range much at all.

 

[cc84]

Guys - the Motortrend Part 2 Trans America Trail video shows them at minute 9 switching through modes on the ATs; Conserve mode takes them up to 308 on the AT's. Hopefully helpful - not sure if posted elsewhere.

Thanks

.......When I last contacted them, conserve was not publicly acknowledged.....

I know "Membership" will eventually feature additional Driving Modes (I think I read that), so I wonder if "Conserve" is one of those that you'll lose, if you don't continue the Trial Membership...?...

 

[RDB]

The thing about range is that you don't need a lot of it except when you do. One of the two factors limiting wider, faster BEV adoption is the lack of charging infrastructure which is used for only perhaps 15% of charging (85% is done at home).

The R1T Large is to have 316 miles EPA range. That is plenty. My first BEV had less than that (294) and I was fine with it. But then the practical range of the R1T isn't 316 miles. The prudent driver will stay out of the upper 10 and lower 10% of the battery range if at all possible. One of these special tires/wheels will cost another 15% reducing working range to (100 - 20 - 15) = 65% of 316 miles which is 205 miles. Now add on a percent per year battery aging loss, several % for the wind and the rain etc. and you might want to think seriously about giving up 10 - 15% for wheels that look nicer. Most of the time it won't matter, of course but when it does it does.

My thinking on this is colored by spending part of last week in an area with sparse DCFC opportunities. I would not willingly have given up 30 - 45 miles range. I have never before been in a situation where I had to be so cognizant of what was in the battery and where the nearest SC was.

In the end it always seems to come back to the admonition to get the biggest battery you are comfortable paying for. We were in a 350 mile Tesla. The 400 mi R1T would have added some additional comfort zone.

I could be wrong, but not sure the range reductions are cumulative like you have it laid out. If the ATs have a 10% reduction it would be 284.4 miles. If you are then avoiding the top and bottom 10%, it would be 227.5 miles. This is a 28% reduction, not 35%.
Again, maybe I am wrong, but setting up the formula correctly makes a difference.

 

[KeithPleas]

You can buy the 20-in wheels and replace the tires with low rolling resistance 275/60 R20 road tires (smaller diameter than the AT tires, the same diameter as the oem 21/22 tires).

275/60 R20 is a very common size, there are a ton of options...

This is my plan - I have Michelin Defender LTX M/S on my GX470 - they are decent in the snow, decent off road, and excellent on the road. Speed rating T up to 118 MPH I can live with, overall diameter 33", Load Index 115 for 2679 pounds, 70k mile warranty...my local Costco has them...so does Discount Tire for $259.

 

[ajdelange]

I could be wrong, but not sure the range reductions are cumulative like you have it laid out. If the ATs have a 10% reduction it would be 284.4 miles. If you are then avoiding the top and bottom 10%, it would be 227.5 miles. This is a 28% reduction, not 35%.
Again, maybe I am wrong, but setting up the formula correctly makes a difference.

What I did is certainly not robust. A robust analysis would consider all 6 loads
A)Drive train
B)Drag
C)Slip
D)Rolling resistance
E)Inertial
F)Potential

It would then look at how much going to the new wheel would increase each of these loads. Obviously it is going to change slip and rolling resistance. But a change in any of B through D implies a change is A because all the other loads flow through the drive train and its loss changes with the change in any other load.

So you are right. For a accurate answer one would have to "set up the formulas correctly" but for a ROM estimate just adding the percent losses arithmetically will generally do.

 

[RDB]

What I did is certainly not robust. A robust analysis would consider all 6 loads
A)Drive train
B)Drag
C)Slip
D)Rolling resistance
E)Inertial
F)Potential

It would then look at how much going to the new wheel would increase each of these loads. Obviously it is going to change slip and rolling resistance. But a change in any of B through D implies a change is A because all the other loads flow through the drive train and its loss changes with the change in any other load.

So you are right. For a accurate answer one would have to "set up the formulas correctly" but for a ROM estimate just adding the percent losses arithmetically will generally do.

Yep, all that is over my head. It does however make a significant difference to the estimate and does not involve any sort of complex math/physics. You know how forums work, someone (many people) will read that and make the blanket assumption of a 35% range hit.

 

[ajdelange]

Yep, all that is over my head. It does however make a significant difference to the estimate and does not involve any sort of complex math/physics. You know how forums work, someone (many people) will read that and make the blanket assumption of a 35% range hit.

If you like we can be a bit more robust and note that if the tires take 15% from an operating range of 80% we’ll have .85*.80 = .68 left for a 32% loss to which we need to add a bit for the drive train. 35% doesn’t look that unreasonable after all.

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