Tire/Rim System Configuration Change

[harveybl]

Apologies if this has been covered but finding exact info has been hard.

I just switched to the defenders 275/60r20 tires. So now I am at the 33” diameter instead of 34.1”. This generates a higher mileage on vehicle for resell and warranty issues, not to mention speed and efficiency display.

what seems like people have done is get service center to switch to the 21” configuration since it aligns with total tire diameter.
They are going to do it but with heavy push back saying that their systems calculate it by rim size not tire with a sensor on rim and tire diameter. That this could cause a fault by it being a different rim size.

my question is has anyone else done this? Has it created a better speed and mileage reporting and efficiency reporting? Any faults or other issues doing the system config change?

Or should I not get them to do it.

also, does having the 33” tire on 20” rims if you don’t get the config changed, does it show a higher mi/kwh then what it should? Thought process is that if this means that if the speedometer is showing 60mph but due to smaller diameter you are actually going 58 mph which also means truck thinks you did more miles than actually traveled, that the efficiency on screens will report a higher mi/kwh?

which if true, the multiple threads of people reporting a gain of 20%+ by going to the M/S2 compared to AT tires could be due to the configuration not being changed?

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[ksurfier]

Apologies if this has been covered but finding exact info has been hard.

I just switched to the defenders 275/60r20 tires. So now I am at the 33” diameter instead of 34.1”. This generates a higher mileage on vehicle for resell and warranty issues, not to mention speed and efficiency display.

what seems like people have done is get service center to switch to the 21” configuration since it aligns with total tire diameter.
They are going to do it but with heavy push back saying that their systems calculate it by rim size not tire with a sensor on rim and tire diameter. That this could cause a fault by it being a different rim size.

my question is has anyone else done this? Has it created a better speed and mileage reporting and efficiency reporting? Any faults or other issues doing the system config change?

Or should I not get them to do it.

also, does having the 33” tire on 20” rims if you don’t get the config changed, does it show a higher mi/kwh then what it should? Thought process is that if this means that if the speedometer is showing 60mph but due to smaller diameter you are actually going 58 mph which also means truck thinks you did more miles than actually traveled, that the efficiency on screens will report a higher mi/kwh?

which if true, the multiple threads of people reporting a gain of 20%+ by going to the M/S2 compared to AT tires could be due to the configuration not being changed?

First, download Speedbox app and check your actual speedo readings eand see if it's off (there's been mixed reports of it being off or not). Difference of 1" means your radius is 0.5" inch off, meaning over the course of a mile the tire rotates 611 times instead of 591. A worn out 34" tire will rotate at 611 times too...

Also reports that distance is measured differently by the computer (a test would be good to see if this is true or not...)...

I would not waste the money on Cal/Programing, are you really concerned that when your odometer hits 103,333 miles, the actual miles will be 100,000?

Hopefully sometime soon Rivian will make it a selectable feature in the software like Tesla has done...

At the end of the day, if you show that the speedometer is not accurate then they are legally obligated to 'fix' it at your cost...whatever that happens to be...

 

[ksurfier]

Question for the people running 35"s...how are you all dealing with these issues?

Are you losing sleep at night that your speedo is reading 2.9% lower than actual and your MPKs are 0.05 MPK lower than actual...

Serious question with so many OCD people on here...

 

[harveybl]

thanks. can you say which Speedbox app as I see multiple on the apple App Store.

 

[ksurfier]

Sure:

 

[harveybl]

Question for the people running 35"s...how are you all dealing with these issues?

Are you losing sleep at night that your speedo is reading 2.9% lower than actual and your MPKs are 0.1 MPK lower than actual...

Serious question with so many OCD people on here...

little bit worse than that I thought.

 

[ksurfier]

little bit worse than that I thought.

I've always been fine if speedo is within ~5 mph (running Toyota trucks and 4runners for 20+ years - think this was the norm...)

 

[Dave Cundiff]

In order to drive legally through Oregon's Coastal Range, I replaced factory 21" with 22" Bright wheels and Michelin X-Ice Snow 275/50R22 before leaving the Portland area. Both are 33" diameter.

So our R1S is calibrated for all-season 33" diameter tires on 21" wheels, but actually running winter 33" diameter tires on 22" wheels. I expected them to record speed and distance similarly, and I think they are.

Later that weekend, my wife was following the R1S with our red Bolt, whose odometer (and presumably speedometer) read about 0.5% lower than actual speed. She noted that when the R1S was cruising at 60, the Bolt's adaptive cruise was showing 59-60. This suggests that the difference between the two is probably between 0.5% and 1.6%.

Last weekend I calibrated the odometer to about 40 miles of known mileposts. With these winter tires, the R1S odometer (and presumably speedometer) are reading about 0.4% higher than actual. This means the R1S odometer reads about 0.9% higher than the red Bolt -- right in line with my wife's observations.

This may be more precision than most want, and it is probably more precision than anyone needs. (Diagnose OCD if you want -- I won't be hurt -- but everyone has preferences, and I have time to figure out this stuff when I'm driving.) But so far, I haven't noticed any problems that seem attributable to the difference between 22" Rivian wheels and 21" Rivian wheels.

Of course, it's possible that the "Take Control Now - System Fault detected" error in Cruise Control has something to do with wheel size. But I doubt it. If you have thoughts about that issue, please put them in the "Take Control Now" thread, not in this one. I intended this comment to relate to tire and wheel size only.

Best wishes!

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