Rivian Forum – Rivian R1T & R1S News, Pricing & Order... banner
21 - 39 of 39 Posts

·
Registered
Joined
·
41 Posts
I still have difficulty believing a 10-15% range hit on 20" wheels vs 21" if the overall diameter of the tire and wheel is the same.
If I put an all terrain tire (like the Pirelli Scorpion) on 21" wheels, would my range suffer 10-15%?
Edit: when I posted the comparison below I was thinking forged steel vs cast aluminum, but the forged and cast are both aluminum making the comparison below incorrect. Thank you Lionel_Hutz for pointing out my mistake.

The 20” is forged versus cast aluminum for the 21” and 22” which makes the 20” heavier (range reduction) no matter what tire is put on it. So the 10-15% is partially AT versus all-season and partially forged versus cast aluminum.

So if you put an AT tire on the 21”s it could be 5-8% loss. Likewise if you put an all-season on the 20” it might be 5-8% instead of 10-15%.

The worst is the forged and AT which is the 10-15% when compared to the cast aluminum with all-season.
 

·
Registered
Joined
·
221 Posts
I still have difficulty believing a 10-15% range hit on 20" wheels vs 21" if the overall diameter of the tire and wheel is the same.
If I put an all terrain tire (like the Pirelli Scorpion) on 21" wheels, would my range suffer 10-15%?
Yes. It is the less efficiency of an AT tire versus a street tire not the 20 versus 21 inch rim

If anything same tire on both a 20 inch will be more efficient than a 21 due to less rotational mass in the fact that tire sidewall is more aerodynamic than rim

The best way to decrease the performance of a vehicle or in terms of efficiency acceleration and braking distance is to put on larger rims. Run the smallest rims that you can fit over your brakes
 

·
Registered
Joined
·
221 Posts
I just went the opposite way. A bunch of my friends have horror stories about AT tires in the snow, and I don't want to buy a second set of wheels/tires for the truck, so 21s it'll be.
AT tires are going to be better in the snow and winter than street tires that come with the 21’s. If you’re concerned about performance in the winter do a dedicated winter tire which is going to be fairly important on a 7000 pound truck
 

·
Registered
Joined
·
3 Posts
The 20” is forged versus cast aluminum for the 21” and 22” which makes the 20” heavier (range reduction) no matter what tire is put on it. So the 10-15% is partially AT versus all-season and partially forged versus cast aluminum.

So if you put an AT tire on the 21”s it could be 5-8% loss. Likewise if you put an all-season on the 20” it might be 5-8% instead of 10-15%.

The worst is the forged and AT which is the 10-15% when compared to the cast aluminum with all-season.
This is incorrect. Forged aluminum wheels are almost always lighter than cast aluminum, particularly the weight for any given strength. The range hit from 20" is most likely due entirely to aerodynamics and rolling resistance.
 

·
Registered
Joined
·
7 Posts
Yeah I'm with you on this one. I think 10% range loss is pessimistic. Does anyone know the weight of the 21 vs 20 wheels? If equal weights, the difference in diameter is actually a (small) contribution in favor of the 20" wheel because of rotational inertia.
AFAIK it's more about the tread and material of the tire. The 21" stock tires are designed for low rolling resistance, and the wheels have those aero inserts to presumably help increase range a bit as well. With the all-terrain tires and wheels you get more drag from both sources.
 

·
Registered
Joined
·
349 Posts
10-15% seems like a pretty big reduction in mileage
I think 10% range loss is pessimistic
10% to 15% is the official answer coming from Rivian. YMMV, literally. You may not understand WHY the range loss is this much, but that's what Rivian has measured. I'm sure if it were significantly less than 10% they'd be advertising that - there's no reason for Rivian to claim a number that's significantly worse than reality. (Note Rivian also says 5% - 10% loss with the 22" wheels, compared to the stock 21".)

Studies that I have seen in the past show that just putting roof-rack cross bars onto an ICE sedan will reduce the MPG by 10% or more(*). Likewise with a bike rack. And if you actually put gear on your roof rack or bike rack, mileage suffers even further. So when I look at Rivian's number for range loss due to chunky wheels as opposed to specially-designed low rolling resistance tires, a 10% loss seems well within the expected range of values. If you see less of a loss on an ICE vehicle when switching tires, it's probably because your original tires were not highly optimized for efficiency.

(*) how much does a roof rack affect mpg - Google Search
 

·
Registered
Joined
·
6 Posts
I'm still debating what I want. I have the 21" road on the configurator. I know most of my driving will be in town. But, I also know I will be going on some off road trails on weekends. I just don't know if it will be often enough to justify all-terrain tires on the truck all of the time.
 

·
Registered
Joined
·
221 Posts
10% to 15% is the official answer coming from Rivian. YMMV, literally. You may not understand WHY the range loss is this much, but that's what Rivian has measured. I'm sure if it were significantly less than 10% they'd be advertising that - there's no reason for Rivian to claim a number that's significantly worse than reality. (Note Rivian also says 5% - 10% loss with the 22" wheels, compared to the stock 21".)

Studies that I have seen in the past show that just putting roof-rack cross bars onto an ICE sedan will reduce the MPG by 10% or more(*). Likewise with a bike rack. And if you actually put gear on your roof rack or bike rack, mileage suffers even further. So when I look at Rivian's number for range loss due to chunky wheels as opposed to specially-designed low rolling resistance tires, a 10% loss seems well within the expected range of values. If you see less of a loss on an ICE vehicle when switching tires, it's probably because your original tires were not highly optimized for efficiency.

(*) how much does a roof rack affect mpg - Google Search
Range loss from an ICE to an EV is NOT an apples to apples comparison. Let’s compare my LX 570 to a R1T. On a flat highway cruising along at 55mph in the LX I get ~17 mpg or about 1950 Wh/mi. The rivian gets ~428 Wh/mi. Physics being physics and increases in energy required to overcome additional force will be the same regardless of ICE or EV. In the LX when I put 2 enduro bikes (yakama front loaders) on the roof I go from 17 mpg to about 15 mpg, ~10% range loss, increase of ~300 Wh/mi from 1950 to 2250 Wh/mi. When I put the same 2 bikes on the roof of my model 3 (different rack, Tesla front wheel off so probably a little more aerodynamic) same trip I would go from ~250 Wh/mi to ~425-450 Wh/mi. 175-200 Wh/mi increase and ~40-50% range loss.

This is why I sold my Tesla roof rack and put on a 2” receiver.

For wheels/tires I think people give tries more credit in effecting range then they really do. I have 3 sets for my LX. studded p-metric 265/60-18 Hakka 7 (winter tires) on 18” tundra rims, LT275/55-20 Michelin defender LTX (highway tires) on 20” OEM rims, and LT 285/70-17 KO2 (AT tires) on 17” rims. I notice no difference at all when I switch between the 3. I put the defenders on the OEM rims to hopefully get better MPG over the KO2’s on 17” when towing the camper long distances when we won’t be doing technical off roading. I’m selling that set this spring.

On our model 3 I notice no difference in Wh/mi when I switch from my summer OEM MxM4 tires on 18” rims to the winter studded Hakka 9 on 18” rims.
 

·
Registered
Joined
·
349 Posts
The link I provided went into substantially more detail than I did in my post above - including breaking down the numbers for sedans vs SUVs and explaining why the results are different. That's why I provided the link ...
 

·
Registered
Joined
·
221 Posts
This is incorrect. Forged aluminum wheels are almost always lighter than cast aluminum, particularly the weight for any given strength. The range hit from 20" is most likely due entirely to aerodynamics and rolling resistance.
Smaller rims and more tire will be more aerodynamic then larger rim and less tire. Smooth Tire sidewall is more aerodynamic then rim.
 

·
Registered
Joined
·
3 Posts
Smaller rims and more tire will be more aerodynamic then larger rim and less tire. Smooth Tire sidewall is more aerodynamic then rim.
I suspect there's a lot more to it than that. Rim design is going to be a major factor (see Tesla's aero rims and hubcaps--I believe the Rivian 21" has a similar aero cap concept). Even things like tire tread and sidewall design are likely to be a factor in aerodynamics. And that's all setting aside tire rolling resistance, which is enormous. (20=A/T, high rolling resistance; 21=A/S EV tire, low rolling resistance; 22=Summer EV tire, higher but unknown w/r/t A/T comparison)
 

·
Registered
Joined
·
3 Posts
Not sure if this was covered elsewhere, but just a simple calculation on the 3 stock tire sizes offered shows a much taller tire on the 20" wheels:

275/65-20 34.1"
275/55-21 32.9"
275/50-22 32.8"

Not sure why they would not make them all the same overall diameter, but they didn't. At this point, I still have the 20" on my reservation, but still thinking about changing after seeing Matt Farah tear up the street and then the dirt trail on the 22" option:

 

·
Registered
Joined
·
221 Posts
I would be very hesitant to take the truck on even simple off road terrain like this on 22’s. Major risk for pinch flats even hitting one basic rock. The 22’a only have 6” sidewall. Watch this video from ~11:30-15:00. The Range Rover defender has 6.5” sidewall on the 20” and weights almost 2k lbs less then the rivian. And to put that in perspective the 20” only has 7” sidewall.

 

·
Registered
Joined
·
397 Posts
I'm with Cole on this one wrt offroading. Also, "much" taller ... I don't know, it's 1.1" (difference in rounding to nearest two decimals), or 1.1/34 = 3.2%.
Are those of us who will run 20" wheels get worse range by 3.2%? Or those of us who will run 21" wheels get better range by 3.2% ;)
 

·
Registered
Joined
·
3 Posts
That video was painful to see the sidewalls pinched twice in the same spot minutes apart. I guess sticking with the 20" option is the way to go. Mileage seems to be pretty good on the 20s anyway based on Kyle Conner's 70mph test.
 

·
Registered
Joined
·
6 Posts
I’ve gone full circle on this. I’m now starting with the 20” all terrain plus a full size spare. And, the spare is the deciding factor for me. If I ever choose to have a 2nd set of aftermarket wheels, they’re sold in sets of 4. I’m better with the idea of no spare on the road than in the back country. If I think later that I want road tires, I’ll be okay with 4 and have more choices.
 

·
Registered
Joined
·
9 Posts
Truck looks so much better with the taller 34" ATs and some sidewall. Real world range looks to be 280 mi highway so that's very respectable. My Model 3 LR is roughly 300 mi highway range...
 

·
Registered
Joined
·
221 Posts
I’ve gone full circle on this. I’m now starting with the 20” all terrain plus a full size spare. And, the spare is the deciding factor for me. If I ever choose to have a 2nd set of aftermarket wheels, they’re sold in sets of 4. I’m better with the idea of no spare on the road than in the back country. If I think later that I want road tires, I’ll be okay with 4 and have more choices.
You can buy sets of 5 aftermarket wheels easily. Another thing to consider with a matching spare is you can do a 5 tire rotation (something I’ve always done when possible) and have the tires last ~20% longer.
Tire Wheel Automotive tire Product Tread
 

·
Registered
Joined
·
221 Posts
That video was painful to see the sidewalls pinched twice in the same spot minutes apart. I guess sticking with the 20" option is the way to go. Mileage seems to be pretty good on the 20s anyway based on Kyle Conner's 70mph test.
And the 20” rim with 34’s only gives you 0.5” more sidewall then that defender had. I really wish rivian would have used smaller brakes to fit a 17” rim or at least at some point makes it an option. Im sure someone will pull off the brembo’s for smaller rotors and calipers to fit better preforming smaller rims.
 
21 - 39 of 39 Posts
Top