20" tire recommendations

[ksurfier]

Really attracted to idea of alternate AS tires for 20" wheel. I am NOT tire knowledgable, so i'm checking my understanding after reading all of these posts. Seems to me higher range will most likely come by going to to a non-standard 275-60-R20 (vs OEM 275-65-R20). Doing that potentially carries a few complications:
1) larger chain stores like DT won't install these non-OEM-size tires - but smaller / local stores will
2) the inflatable spare (in the R1S) will no longer be usable - different size
3) The chain stores like DT "WILL rotate" the non-OEM-size tires after being installed.
4) claiming "credit" under a manufacturer warranty program will be more challenging

Am i correct in any / all of those assumptions? None of them?

Thanks so much!

Jemkewl has a good suggestion of asking your local tire place.

1) Reports of people getting DT and Costco to install. There's a separate thread here where DT is in process of responding about 115/116 load rating, bottom line is multiple DTs are installing 115 load tires with no issues....

2) Only 3% difference, so should be fine for emergency...

3) I routinely run non-OEM size tires and never have issue with service/rotations...(based on measurements, OEM 20" tires should be rotated every 5k miles). If I had 21/22" tires I'd prob. rotate them once at ~8k, they likely wont survive another rotation after that....

4) I have had credits thru Michellin for non-OEM size tires, but you have to be able to prove rotation every 5-8k miles. Usually it's not very much and then you are stuck buying same brand...

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[av8or]

Haven’t read this entire thread as it’s gotten long and veered of course a couple times, but if anyone is looking at Cooper Discoverer ATP II tires, here’s my results @70mph in conserve mode.

https://www.discounttire.com/buy-tires/cooper-discoverer-atp-ii

This was a second test at 60psi cold up from 50psi which was identical at 2.17.

The tires have an aggressive looking sidewall, but a fairly tame tread pattern and are quite on the road, but should still be somewhat tough off-road. At $305 a tire I couldn’t see buying the OEM noise makers again, and am very happy with these tires. As in my past experience the people at discount tire took good care of me and my truck.

 

[Scrambler]

2) the inflatable spare (in the R1S) will no longer be usable - different size

Are there two different version of the compact spare, one for 20" wheels and one for 21" & 22" wheels? I think there is just one spare for all R1S's. Since 275/60R20 is roughly the same overall diameter as the OEM tires on the 21" & 22" wheels, it shouldn't be a problem.

 

[EarlyAdptr]

Here's another way to look at it:
Easiest to just follow Rivian's recommendation of 48 psi @ 60F (see below).
Efficiency-wise, it wont make much difference (maybe 0.1mi/kwh 44 psi vs 51 psi).
Follow these inflations for Temp (Cold overnite) (If >120F may need to bleed a tiny bit out...if below freezing prob. want to bring the pressure back up to 48-49 psi):
IF OCD, you could in theory adjust the pressure to ~49-50 every couple weeks in the AM.

46 psi​	@20F; at this point adjust to ~49
47 psi​	@40F
48 psi​	@60F
49 psi​	@80F
50 psi​	@100F
51* psi​	@120F; at this point adjust to ~49

Tires are designed to have a 10% safety factor due to changes in temperature and/or pressure.
Around 43 psi the safety factor is gone (so that's a pretty good number to stay above).
* - 51 psi is the max, but going a few psi over the max, say ~53 or so shouldn't be a problem specially if short duration (wouldn't want to have them at 55 consistently for weeks/months).

Looking forward to your report and photos of the AWs with the Grabbers, how many miles did you get out of the originals?

Hey @ksurfier, you seem to have a fair amount of knowledge of tires and pressure. I on the other hand know nothing (other than what I'm learning here)...

I just had a wierd experience at Discount Tire. swapped my OEM 20" Perelli's out for Michellin 275-60-R20 Defender M/S 2 tires. Inside the shop, they told me their computer said PSI should be 41. Outside, they told me never trust their computer, put at what door jamb says - 48. I drive a bit, and the left tires are at 41, and the right tires are at 45. Ugg.. Had them set all tires to 48.

I believe the Michelins have a max pressure of 50. So, what's the right pressure for me on my R1S?

 

[ksurfier]

Looks like you are near sea level so 50 cold should be fine, 2-3 over the max is fine during driving especially.

Surprised they would set them lower than 48, in theory 41 meets your empty load weight needs…

I would fine tune it based on efficiency and ride comfort…

For simplicity maybe just set to 48?

 

[EarlyAdptr]

Looks like you are near sea level so 50 cold should be fine, 2-3 over the max is fine during driving especially.

Surprised they would set them lower than 48, in theory 41 meets your empty load weight needs…

I would fine tune it based on efficiency and ride comfort…

For simplicity maybe just set to 48?

Thank you. Yes, near sea level. But taking a trip soon driving down I-5 (west coast) - higher elevations and warmer. I'll stick with 48 for now.

PS I assume all these #'s represent pressure at 'cold' temperatures. That correct?

 

[ksurfier]

Thank you. Yes, near sea level. But taking a trip soon driving down I-5 (west coast) - higher elevations and warmer. I'll stick with 48 for now.

PS I assume all these #'s represent pressure at 'cold' temperatures. That correct?

Yes, all pressures are typically cold. You can always check treadwear with a gauge to make sure tire is wearing eveningly, not bad to check your tires every 60-90 days for damage, top off pressure…

 

[beyondgravity]

So what is the most efficient wheel tire combination? The stock 21s or somebody has figured out a way to out do it. Is it also the least noisy and the best cost of ownership?

I have the stock 20 (all dark) and have an appointment to move to stock 21 end of this month with Rivian mobile service; not sure whether it is a right move.

 

[ksurfier]

Best bet to first try the 34# General Grabber HTS60 or Pirelli AS+3 (both in 275/60R20 size), once you go 21” you are stuck with only one tire option…I’m sure you could trade someone for their 21s plus some cash.

 

[beyondgravity]

I actually got used 21s from another Rivian owner. So I have both at this point.

 

[ksurfier]

You might ask someone here with 21s what they think (I'd be guessing)...

 

[Discount Tire]

Hey @ksurfier, you seem to have a fair amount of knowledge of tires and pressure. I on the other hand know nothing (other than what I'm learning here)...

I just had a wierd experience at Discount Tire. swapped my OEM 20" Perelli's out for Michellin 275-60-R20 Defender M/S 2 tires. Inside the shop, they told me their computer said PSI should be 41. Outside, they told me never trust their computer, put at what door jamb says - 48. I drive a bit, and the left tires are at 41, and the right tires are at 45. Ugg.. Had them set all tires to 48.

I believe the Michelins have a max pressure of 50. So, what's the right pressure for me on my R1S?

We apologize for your recent experience. We would like to look further in to this to make sure you're taken care of. Hope you don't mind us sending a DM.

 

[EarlyAdptr]

We apologize for your recent experience. We would like to look further in to this to make sure you're taken care of. Hope you don't mind us sending a DM.

Thank you @Discount Tire , you guys are awesome. That store is great and I've had all of my cars' tire needs serviced there - alway happy. I'm sure this is just an outlier. My reason for posting here wasn't to complain with the store, but rather to help me get to complete understanding of PSI.

Thank you for reaching out. DM'd you off line.

 

[R1Sky Business]

My truck with 21's was a paltry 2.14 m/kWh. My truck with Recon Grapplers 275/60r20 is a hysterical 1.75 m/kWh... but they look cool and I'll probably have them on my truck for years...

AT Grapplers?

 

[ForeverOnTheWaitlist]

I was just about to buy Defender LTX MS/2. )Bought the MS but Costco balked at the weight rating last summer). I saw it was excluded due to width but it has the weight rating, efficiency and mileage lacking in several others. For someone that only does occasional trailhead off-road driving, does the MS/2 have any fatal flaws or flaws due to the < 8" width ? It's odd that given the same 275/60/20 it's size is that much different.

I saw one other post (can't find) where the OP said he removed MS/2's due to poor handling. Not sure if any others have experienced that who installed that posted on this thread. FWIW I plan on using two sets. Winter/Summer. I'm in Central Oregon where we have hills and ice. I kept the stock pirelli's and they did well enough in limited use but a single bad ice melt day is enough to motivate me to get the best possible ice performance. Pehraps with the 115 weight rating change at DT, I can get Michelin Ice-X next winter.

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