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Discussion Starter · #1 ·
I've done a bit of reading on R1T wheel sizes, and wanted to get opinions here.

I ordered 22" rims for city/highway/dirt road driving, and plan to use an extra set of 18" rims (18x8.0 +40 5-100.0/114.3) I have for off road/winter driving. The rims I have fit a P235/65R18 Toyo Open Country tire, for example.

A couple of questions:
Do you think that using narrower tires (40mm (275-235)) will cause any issues?
Do you think the computer can compensate for road speed, turning and suspension?
What other size tires should I consider?

From the Pirelli and Rivian press releases about the custom tires I got the following sizes:
  • 20” Rim – All Terrain Tires – 275/65 R20
  • 21” Rim – All Season Tires – 275/55 R21
  • 22” Rim – Sport All Season Tires – 275/50 R22
 

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From what I've read, the smallest wheel size is 20" in order to accommodate the front brakes.
I've read similar limitations; nothing smaller than 20".

Do you think that using narrower tires (40mm (275-235)) will cause any issues?
Do you think the computer can compensate for road speed, turning and suspension?
With the exception of what other size tires to consider, have you presented your questions directly to Rivian? If not, that would be my advice.
 

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20” Rim – All Terrain Tires – 275/65 R20
21” Rim – All Season Tires – 275/55 R21
22” Rim – Sport All Season Tires – 275/50 R22
Yeah these are the wheel/tire sizes.
The first one has a diameter of 34.1 inches.
The second and third are 32.9 and 32.8 respectively.
I don't know how Rivian will account for the ca. 3 percent difference; however:

Your proposed P235/65R18 has a diameter of only 30 inches. That's around 10% different, which is a lot.
 

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I've done a bit of reading on R1T wheel sizes, and wanted to get opinions here.

I ordered 22" rims for city/highway/dirt road driving, and plan to use an extra set of 18" rims (18x8.0 +40 5-100.0/114.3) I have for off road/winter driving. The rims I have fit a P235/65R18 Toyo Open Country tire, for example.

A couple of questions:
Do you think that using narrower tires (40mm (275-235)) will cause any issues?
Do you think the computer can compensate for road speed, turning and suspension?
What other size tires should I consider?

From the Pirelli and Rivian press releases about the custom tires I got the following sizes:
  • 20” Rim – All Terrain Tires – 275/65 R20
  • 21” Rim – All Season Tires – 275/55 R21
  • 22” Rim – Sport All Season Tires – 275/50 R22
Do you know that these rims will meet the fitment? That is bolt pattern, hub, offset,…. Going down from a 34 to a 30 would require much more positive offset to maintain scrub radius. Also are said rims weight rated for a 7k lb truck? And 235 is super narrow for something the size of the Rivian. I run 265/60-18 Nokian Hakka 9’s for my winter tires on my LX and 285/75-17 in the summer.
 

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Rivian R1T (Adventure - CR, BM, 21", Ordered 10/5/2021, Delivered 6/24/2022), Suburban 2500, VW ID.4
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Wheels are too small to clear the brakes (from what the "journalists" are saying), and the wrong bolt pattern. Based on the bolt pattern and tire size, they seem to be for a much lighter vehicle, and even if you could fit them, I wouldn't think they are rated for the weight of the Rivian.

Long story short, you are going to need new wheels, and will want something closer to a 33" tire.
 

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Discussion Starter · #7 ·
Wow this is all super helpful! I never considered that the brakes need to fit inside the rim. Also didn't consider that the tires just may be too small.

So if my plan is to do mostly highway and city driving, but occasional back country (not rock crawling) - should I get the 22, 21, or 20?

Or should I stick with the 22's and get a new set of wheels and rims for more adventurous driving. (Feel like I'm answering my own question here...)
 

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Wow this is all super helpful! I never considered that the brakes need to fit inside the rim. Also didn't consider that the tires just may be too small.

So if my plan is to do mostly highway and city driving, but occasional back country (not rock crawling) - should I get the 22, 21, or 20?

Or should I stick with the 22's and get a new set of wheels and rims for more adventurous driving. (Feel like I'm answering my own question here...)
22’s are completely pointless on anything. For any vehicle for the best performance get the smallest rim that will fit over the brakes, so get the 20”.
 

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Rivian R1T (Adventure - CR, BM, 21", Ordered 10/5/2021, Delivered 6/24/2022), Suburban 2500, VW ID.4
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6-5.5” is standard GM 1/2 ton and Toyota 4Runner/Taco. Hub bore and offset matters almost as much as boot pattern.
Don't forget Rivian uses 5x5.5, not 6, so regardless of bore or offset none of those will fit.
 

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22’s are completely pointless on anything. For any vehicle for the best performance get the smallest rim that will fit over the brakes, so get the 20”.
Incorrect. The 20" with AT's are the least efficient combo offered on the Rivian. They lost 10-15% of Range, the highest EPA range rating was achieved on the 21" option set and the 22" set loses 5-10% of range. A lot goes into range efficiency, stopping needs and capabilities and off road ability, wheel sizes can be coupled with the correct tires to be as effective in many driving conditions. 18" bead lockers are common place and smaller ones too. But NASCAR just moved from 15" to 18" wheels and increased their efficiency.
https://insideevs.com/news/530883/rivian-r1t-r1s-epa-range/
 

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One needs to consider the wheels and the tires, and their parameters, separately.

Tire tread matters for friction
Tire overall design and materials matter for deformation (hysteresis)
Tire shape matters for aerodynamics
Tire weight matters for rotational mass
Wheel total weight and distribution matter for rotational mass
Wheel diameter matters for rotational mass
\Wheel aerodynamics matter for drag

Examine your wheel tire combo under these parameters and you'll be able to figure out whether it's efficient or less so
 
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