Scorpion AS+ tire swap (from 20" Scorpion AT) - WOW big difference

[JJE]

A bit more interesting math.

The diameter of the 20 inch rims with 275/60/20 tires is 838 mm. The diameter of the 21 inch rims with the 275/55/21 is 836 mm. This means that when you put a Scorpion AS on a 20 inch rims you are basically creating an efficiency combo essentially equivalent to the 21s. The diameter difference is only 0.3%

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[GZR1S]

Interesting, if we can use 275/60/20 then I might switch from 22s to 20s. So many options for 275/60/20

 

[BrayBay]

Fantastic post, thanks for sharing. I was looking at this exact tire also as a replacement for the AT.

Did you have your mechanic do the swap just because you had a good relationship, or was it because it not possible to have the tire store do it? Just curious if I need to make a tire changing friend too.

 

[cohall]

I'm a dummy, so hang with me here. But isn't any calculation of efficiency unreliable since the car is still calculating distance based on an incorrect tire size. Essentially, the car is calculating distance based on the external circumference of the 20, but is traveling in reality a shorter distance of possibly ~3% based on a calculator I found on the internets. In order to know actual actual efficiency you would need to equate for the shorter distance traveled vs the distance the car thinks you went.

Or am I an idiot (which is certainly possible)?

 

[JJE]

You are not an idiot! If you look at my math a few posts ago you'll see I deducted 3% as my last step in the order of operations.

When I take the car in for a wind noise issue in May (!!@ first appointment available) i will try to convince Rivian to set my car to think it has 21s. That should make the default range estimates snd everything else accurate.

I asked my mechanic bc I trust him (he has taken care of our cars for years) and he is very careful.

 

[Florida Boy]

Thank you for posting this! I've been waiting for the right non-AT tire to come out for the 20"s. I'm not super familiar with tires and their load ratings, but are these overloaded or just right at the recommended load?

 

[Kuro-Rivian]

cool. i wonder if Rivian service will be able to calibrate it in some way or if it even needs it. i know folks have been getting recalibrated when they switch wheel sizes but not sure what happens when you keep the same wheel with a different tire.

They absolutely WILL NOT do it. You can have them recalibrate to the 20" the 21" or 22" OEM tire "packages." Which I've done. But they will not calibrate to a custom tire size. They don't have the capability. More so each of the drive modes is programmed to a certain tire OEM diameter.

 

[AARivian48]

Thank you OP for this information. I feel like this is something I can do that could improve the efficiency and also road noise and improve ride quality.

What was the cost of these new tires?

 

[the long way downunder]

My R1S was delivered with the 20 ATs - I would have preferred the 21s but got faster delivery by taking the 20 ATs. I just switched the AT tires for the Scorpion AS+ tires.

Big difference. Quick impressions:
1. Immediate 20% improvement in efficiency (adjusting for the fact that the car computer hasn't been recalibrate yet to adjust for the 3% circumference difference). Photo attached from my stop-and-go beltway traffic drive this morning.
2. Major drop in noise. Drone from ATs was getting very audible. These are silent.
3. Significant improvement in ride quality especially over larger bumps
4. Noticeable improvement in steering sharpness and highway tracking.
5. Overall, glad to have the forged 20 inch rims. But very glad I changed out the tires. My off road use is limited to when I take the driveway turn too tightly and take out the begonias.

Now what am I going to do with these giant AT tires in my garage...

Looks like a decent road tire, I'm sure it's rolling resistance is half of the AT.
Not available in 275/65R20, so some of the 2.79 miles/kWh may be that the vehicle is not calibrated for the smaller overall diameter. It's about 3.2% – in my experience, for such a large overall tire, not a concern to drop from 65 to 60, but it's surprising for a tire shop to install a non-standard fitment these days.
If you have the AT spare, be especially careful if the spare goes on … no matter the electronics, having a new tire with full tread on the same axle as a worn tire and a worn tire that's a smaller diameter can have a steering effect under acceleration and lift-off trailing accelerator (regen.)

I know Rivian has improved calibration (though it's still a visit to the service center, which is a waste of time, it's all software and easily done OTA) and I think I read someone say after changing overall tire diameter the vehicle speedometer was still correct (compared to a phone GPS speed) … which is something new.

 

[JJE]

Total damage for the 4 tires was $950 from Walmart, no less.

These tires really transformed an already awesome vehicle. I drove back and forth today from suburban MD (DC area) to the marina on the Chesapeake where we keep our sailboat (78 degrees and sun today - in February- it would have been the sin of ingratitude not to play hooky from work).

The country roads on the last 15 mile stretch to the Bay are beautiful and winding. The car just molded itself to the road with the new tires. It felt like liquid. I can't explain.

 

[goldburger]

That efficiency is an incredibly small sample size. I have gotten almost

I'm sure it's rolling resistance is half of the AT.

ya think that much? The perillis don’t look too aggressive.

 

[the long way downunder]

That efficiency is an incredibly small sample size. I have gotten almost

ya think that much? The perillis don’t look too aggressive.

True. I think Rivian chose a single tire manf with a range of tires for the load rating and wanted an off-road tire with on-road efficiency. The problem being the tire those chose turned out to be a poor compromise, not good on any surface in my experience. I switched to a Nokian LT3 full winter snow tire and it is excellent in snow and better mi/kWh on asphalt than the factory Pirelli.

 

[abirozy]

I have 21's but this makes me want to get some 20's.

 

[R1Sky Business]

cool. i wonder if Rivian service will be able to calibrate it in some way or if it even needs it. i know folks have been getting recalibrated when they switch wheel sizes but not sure what happens when you keep the same wheel with a different tire.

Rivian won't calibrate anything they don't sell.

 

[R1Sky Business]

This is freaking amazing.

Everyone loves Rivian today!!!!!

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