R2 Tire Size = 275/50R21

[R1 EVY]

Width of the tire in mm/ratio of the sidewall relative to the width/radius of the wheel.

265/75/R20 means a 265mm wide tire with a 198mm sidewall (265x.75) and a 20" wheel. 198mm + 198mm + 20" = approximately 35" diameter tires. Generally speaking, more sidewall is better for off-road performance and comfort, so if you have a limit on the overall diameter of the tire you'd rather have a smaller wheel and more sidewall.

Okay, that totally makes sense. So the 20's seem to have the most options (compared to 21's or 22's) because of the larger sidewalls but they are the worst mileage because of weight, resistance, etc...?

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[feifan]

Ok. Here is a dumb question from a lazy person. Is it same us R1? Would I be able to use it in my R1.

The R1's 21" tire is 275/55R21, so its sidewall (and diameter) is bigger. The R2 tire might fit on a R1, but your odometer and speedometer would be off (unless Rivian adds software support), and without load details, it's unclear whether there would ever be an R2-sized tire that could handle the weight of R1.

 

[feifan]

So the 20's seem to have the most options (compared to 21's or 22's) because of the larger sidewalls but they are the worst mileage because of weight, resistance, etc...?

Not necessarily due to the size, but most of the 20" tire options out there for R1 are more rugged, which means more resistance in the tread and may be heavier — both of those factors would reduce efficiency. Also, only Rivian's 21" wheel comes with aero caps, which help improve efficiency a little bit by reducing aerodynamic drag from the spinning wheel.

 

[R1 EVY]

Not necessarily due to the size, but most of the 20" tire options out there for R1 are more rugged, which means more resistance in the tread and may be heavier — both of those factors would reduce efficiency. Also, only Rivian's 21" wheel comes with aero caps, which help improve efficiency a little bit by reducing aerodynamic drag from the spinning wheel.

Got it. I'd like to optimize efficiency, all season, and snow.

 

[Riviot]

Okay, that totally makes sense. So the 20's seem to have the most options (compared to 21's or 22's) because of the larger sidewalls but they are the worst mileage because of weight, resistance, etc...?

@feifan only speaks to OEM 20s with stock tires, which are worse efficiency because they're All Terrain (AT). You can put different tires on them at different sizes, and even different wheels! Search around the forum for options, read up on load index, and just humor me by searchimg "2363" ?

I look forward to your mind-blowing realizations in other threads.

 

[R1 EVY]

@feifan only speaks to OEM 20s with stock tires, which are worse efficiency because they're All Terrain (AT). You can put different tires on them at different sizes, and even different wheels! Search around the forum for options, read up on load index, and just humor me by searchimg "2363" ?

I look forward to your mind-blowing realizations in other threads.

I saw this interesting thread by an @Riviot
https://www.rivianforums.com/forum/threads/r2-tire-size-275-50r21.25253/page-2#post-501691

Step 1: Get some cheap wheels
Step 2: Strip and prime
Step 3: Spray in satin black (only acceptable finish/color
Step 4: Take new tires to be mounted a week later because Amazon/Simple Tire took a while to correct your order after sending half of the wrong size
Step 5: Clone the sensors with the Smart Sensor Pro+ TPMS sensor programmer
Step 6: Come home a happy camper and patiently wait for winter
Step 7: Install at winter and hit the
trails

Thanks man!

 

[Riviot]

I saw this interesting thread by an @Riviot
https://www.rivianforums.com/forum/threads/r2-tire-size-275-50r21.25253/page-2#post-501691

Step 1: Get some cheap wheels
Step 2: Strip and prime
Step 3: Spray in satin black (only acceptable finish/color
Step 4: Take new tires to be mounted a week later because Amazon/Simple Tire took a while to correct your order after sending half of the wrong size
Step 5: Clone the sensors with the Smart Sensor Pro+ TPMS sensor programmer
Step 6: Come home a happy camper and patiently wait for winter
Step 7: Install at winter and hit the
trails

Thanks man!

There are a ton of aftermarket options out there, I saw the 2363 as a fun project and it absolutely was, plus I love the slightly wider stance.

If you go this route, post pics in that thread of wheels you find so we can vet them! Folks have been sorely disappointed by incorrect wheels.

If I wasn't into refurbishing, I'd get the MSWs and throw some 275/60R20 Michelin Defender LTX M/S2 on them, solid build and folks won't nitpick over load index.

 

[R1 EVY]

There are a ton of aftermarket options out there, I saw the 2363 as a fun project and it absolutely was, plus I love the slightly wider stance.

If you go this route, post pics in that thread of wheels you find so we can vet them! Folks have been sorely disappointed by incorrect wheels.

If I wasn't into refurbishing, I'd get the MSWs and throw some 275/60R20 Michelin Defender LTX M/S2 on them, solid build and folks won't nitpick over load index.

I have a friend who has a powder coating business so that would be cool to use him. I also like finding a $2k solution to a $5k problem. So doing this at the end of the season should net some great deals.

I'll definitely post before I buy.

 

[AirplaneDr]

I was wondering today about what the tire/wheel size is on the R2 validation builds. I wasn't able to find anything definitive that has been posted. Using the photos posted and some math it looks like the R2 validation builds are running on different rubber size than the R2 prototype:

255/55R20

Here is the info and math using measurements taken from the recent photos of the validation build pulling out of the Rivian facility.

The tires:

These are BFG Trail-Terrain T/As not the Pirelli tires seen on the original prototype from 2024.

I downloaded the full photo and pulled measurements using photoshop.
The measured wheel base on the photo is 8.15625" which is a 14.17318008 ratio with the 115.6 published wheelbase.

The rims diameter measured 1.40625" (averaged between the front and back because the R2 validation build photo was at a slight angle) and with the 14.173 ratio is 19.93103448" or 20."

The wheel diameter measured 2.1875" average and with the 14.173 ratio is 31.00383142 or 31."

Comparing those dimensions to the BFG Trail Terrain specs points to 255/55R20. It makes sense as this an XL load range tire and the R2 is expected to be in the 5000-6000 pound range.

 

[UnsungZero_OldTimeAdMan]

I was wondering today about what the tire/wheel size is on the R2 validation builds. I wasn't able to find anything definitive that has been posted. Using the photos posted and some math it looks like the R2 validation builds are running on different rubber size than the R2 prototype:

255/55R20

Here is the info and math using measurements taken from the recent photos of the validation build pulling out of the Rivian facility.

The tires:

These are BFG Trail-Terrain T/As not the Pirelli tires seen on the original prototype from 2024.

I downloaded the full photo and pulled measurements using photoshop.
The measured wheel base on the photo is 8.15625" which is a 14.17318008 ratio with the 115.6 published wheelbase.

The rims diameter measured 1.40625" (averaged between the front and back because the R2 validation build photo was at a slight angle) and with the 14.173 ratio is 19.93103448" or 20."

The wheel diameter measured 2.1875" average and with the 14.173 ratio is 31.00383142 or 31."

Comparing those dimensions to the BFG Trail Terrain specs points to 255/55R20. It makes sense as this an XL load range tire and the R2 is expected to be in the 5000-6000 pound range.

Like R1, they will most likely have multiple wheel and tire options.

 

[MacO512]

As long as they have standard wheel sizes like 20" or 18" or whatever I'm good with it.

If they have another stupid 21" Rivian only size as they did with the R1 gen1 I'll be disappointed.

I ultimately paid for the 20s on my R1 but wouldve preferred to save that cash and eventually just use the stock wheel for snow tires or such.

But that 21 was totally worthless! No tire options except some crappy overpriced OEM.

Sorry /end Rant

 

[JasonK]

It also does not make any sense to have 21 or 22 rims as they will be heavier. I am hoping for an 18 inch option. But if it is an expensive option I may just buy aftermarket 18 inch rims.

 

[UnsungZero_OldTimeAdMan]

It also does not make any sense to have 21 or 22 rims as they will be heavier. I am hoping for an 18 inch option. But if it is an expensive option I may just buy aftermarket 18 inch rims.

Don’t count on it. 18” wheel probably way too small for size of brakes. R1 has lack of tires choice for the 21” not because of the wheel size, but because of the specific tire size of 275/55R21 and 116H.

 

[elektrode]

As long as Mich keeps making an LTX that fits, I’m good.

 

[bradrh]

Don’t count on it. 18” wheel probably way too small for size of brakes.

Lots of pickups and large vans have 16" wheels.

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