Discontinuation of 21” wheels

[Alanparkcity]

I’m confused how the 22” wheels are more efficient than the current 21” wheels?

21” tires are the most efficient tires for the Rivian. If you go to their site you will see that 21” road tires get 25-30 miles more range. Worst for range are all terrain tires.

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[Cascadian]

I'd like to fact check the weight thing, steel has a better strength to weight ratio than rubber (much more so, that's why we don't build cars out of rubber). Do you have the actual weight for a Rivian tire in each size, and the associated wheels?

That said, unsprung weight is only going to impact city efficency, it's going to have no effect on highway range. That's why I didn't mention it.

Contact patch will actually be smaller with the bigger wheels. That article saying otherwise is because it's generally smaller when you have a smaller outside diameter (though even that varies, as it depends on inflation pressure, so it shouldn't really differ much). When you're comparing something like the Rivian 21" and 22" wheels, the outside diameter is the same, the difference is the 22" has less rubber and will flex less, resulting in a smaller contact patch when inflated to the same pressure.

Edit: Found this thread https://www.rivianforums.com/forum/threads/21-wheel-weight-as-delivered.5576/

88/89lbs for 20"s, 85lbs for 21"s, 80lbs for 22"s which fits my suspicion, larger wheels are lighter.

I am pretty sure those weights are wheel+ tire, not just wheel.

See gear shop for data
86 lb for 20s
79 lb for 21s
83 lb for 22s

 

[UnsungZero_OldTimeAdMan]

21” tires are the most efficient tires for the Rivian. If you go to their site you will see that 21” road tires get 25-30 miles more range. Worst for range are all terrain tires.

Not entirely accurate. 275/55R21 size alone doesn't make it most efficient. Size, tire construction, weight, tread design and rubber compound are all factors. It is however the most efficient of all factory options, and only slightly more efficient than the 22" option. Is it the most efficient possible? We don't know what tires Rivian tested and how they arrived at that particular Pirelli tire. And without a standardized testing procedure, done at a common location under common conditions, we may never know which tire is indeed king.

 

[edman007]

I am pretty sure those weights are wheel+ tire, not just wheel.

See gear shop for data
86 lb for 20s
79 lb for 21s
83 lb for 22s

Yes, exactly, it's total weight (and weight distribution) that matters. If a bigger tire wheel is 5 pounds heavier, but it means it needs 7lbs less of rubber, then it reduces the wheel mass and very likely reduces the rotational inertia which is what you care about for weight.

The reason the 22s on the Rivian do worse than the 21s in the 2024 model is likely due to lack of aero cover and a softer rubber compound that's less efficient. But the general case, if you care about efficency is make large wheels, and carefully carve out all the metal you can and couple it with high efficency tires. Totally flat aero covers are probably the best you can do without designing the rim to look totally flat and skipping the aero covers, and that's basically what it seems Rivian is doing. The 22"s also probably weigh more than the 21"s because they focused less on weight and more on looks. Focusing on weight they can probably beat the 21"s on weight (and beat the gear shop numbers), and with a better tire compound get more efficient on the 22"s

 

[ksurfier]

Reason why 21" should be discontinued (20" rim plus 33" tire is naturally more efficient):
22" is less efficient than 21" since the rim is 10% heavier...

Lighter weight rims and tires can achieve ~5% better efficiency than the 21" OEM setup.

Aftermarket (EST.)	Weight	EST Range	Rim	20" Tire	MPK
20" AWZZ-HTS60	60	328	26	34	2.50
20" AWZZ-AS+3	64	324	26	38	2.45
20" AWZZ-D.M/S2	66	321	26	40	2.40
20" AWZZ-CV4S	67	320	26	41	2.35
20" OEM-CV4S	81	310	40	41	2.30
OEM Setup	Weight	EPA Range	OEM Rim	OEM Tire	MPK
21" OEM	79	321	42	37	2.40
22" OEM	83	303	46	37	2.20
20" OEM	88	289	40	48	2.10

 

[FLTANK]

Rivian, Tesla, BMW, Mercedes, Lexus, Audi, Porsche, Range Rover, and Bentley all have 21" wheel options from the factory just to name a few. Yes the OEM tire sizes vary but keep in mind virtually no manufacturer offered 21" wheels from the factory even as recently as 2020, so I think we can relax a bit on whether or not we'll be able to find 21" tires in the future….it will be okay. If you want to feel better about the Rivian, check out the price of the tires for the Silverado EV with 24s…yikes.

 

[moosetags]

The 21's were thousands cheaper than the others. If I want to go to 20's, I can do that at any point if I feel it is what I want to do. For now, we will stick with the 21's. We really like the looks of the 21's sans the the aero covers.

Brian

 

[poldim]

I must have missed the announcement that they got rid of the 21's?

 

[Jason765]

I must have missed the announcement that they got rid of the 21's?

Same

 

[anthonysfl]

Yes, exactly, it's total weight (and weight distribution) that matters. If a bigger tire wheel is 5 pounds heavier, but it means it needs 7lbs less of rubber, then it reduces the wheel mass and very likely reduces the rotational inertia which is what you care about for weight.

The reason the 22s on the Rivian do worse than the 21s in the 2024 model is likely due to lack of aero cover and a softer rubber compound that's less efficient. But the general case, if you care about efficency is make large wheels, and carefully carve out all the metal you can and couple it with high efficency tires. Totally flat aero covers are probably the best you can do without designing the rim to look totally flat and skipping the aero covers, and that's basically what it seems Rivian is doing. The 22"s also probably weigh more than the 21"s because they focused less on weight and more on looks. Focusing on weight they can probably beat the 21"s on weight (and beat the gear shop numbers), and with a better tire compound get more efficient on the 22"s

Larger wheels are less efficient than smaller wheels.

 

[TyeeMike]

in the long long ago say 80-90 ish mustangs had 390mm wheels one of the worst choices ever. hope the 21's dont end up in that pile

 

[Joe Hoffman]

This is an incredibly long thread for a subject that’s pure speculation. Where did this rumor start that they’re getting rid of the 21s?

 

[edman007]

This is an incredibly long thread for a subject that’s pure speculation. Where did this rumor start that they’re getting rid of the 21s?

The EPA test results specify the wheels the results apply to. Rivian has released the results for the 2025 Dual Standard/Large/Max and it doesn't include any 21" options.

They also didn't include any tri or quad motor options either, so maybe they just tested 21s under a different group that hasn't been released yet. But honestly, that seems unlikely.

 

[edman007]

Larger wheels are less efficient than smaller wheels.

He only covered Tesla tires. And honestly, it's not really that accurate. Specifically out of the sizes he compared, only the 18 and 19 inch Model 3 tires were the same width. The model X and Model S tires were different widths. I agree with him that out of those specific tire choices the smaller one is more efficient. But that doesn't necessarily apply in general, for the model 3 18 and 19 inch options don't have the same tire model or wheel design. So this could be entirely an aero or rubber compound difference.

And the current Rivian lineup is a great example, it absolutely does not hold that smaller is better

 

[R1Sezejay]

Reason why 21" should be discontinued (20" rim plus 33" tire is naturally more efficient):
22" is less efficient than 21" since the rim is 10% heavier...

Lighter weight rims and tires can achieve ~5% better efficiency than the 21" OEM setup.

Aftermarket (EST.)	Weight	EST Range	Rim	20" Tire	MPK
20" AWZZ-HTS60	60	328	26	34	2.50
20" AWZZ-AS+3	64	324	26	38	2.45
20" AWZZ-D.M/S2	66	321	26	40	2.40
20" AWZZ-CV4S	67	320	26	41	2.35
20" OEM-CV4S	81	310	40	41	2.30
OEM Setup	Weight	EPA Range	OEM Rim	OEM Tire	MPK
21" OEM	79	321	42	37	2.40
22" OEM	83	303	46	37	2.20
20" OEM	88	289	40	48	2.10

Is the EPA Range set in Conserve or
All Purpose Mode?

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