Speedo accuracy with 20s

[mikehmb]

FYI - My truck is configured and programmed for 21s. I swapped 20s with OE tires onto the truck without a reprogramming.

The speedo, after the swap, is now dead-on. At 65, after multiple tests in different locations (Sierras, central valley, and all around the bay area) it seems to match perfectly to a phone GPS app.

What are the benefits to getting the truck updated to match the config, besides possibly improving accuracy on the guess-o-meter?

Also, range reporting and energy consumption are weird. The % used doesn’t appear to match the 15-minute meter or the odometer / “about” screen. Perhaps these will be fixed if/when I do the update?

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[SSteveEV]

This is different but I also have noticed that if I have cruise set to 60mph, and while driving reset the trip meter, it'll say avg speed 59 not 60. So perhaps they are factoring in the real speed in one but not the other. Been a while since I played with that.

 

[NY_Rob]

What are the benefits to getting the truck updated to match the config, besides possibly improving accuracy on the guess-o-meter?

In the past Rivian SC people have told owners "we need to re-calibrate the cameras" if you change tire size. Honestly, that really doesn't make much sense on a vehicle where you can vary ride height by as much as 6.5" at will?

 

[Lizardo]

following

 

[Fes]

FYI - My truck is configured and programmed for 21s. I swapped 20s with OE tires onto the truck without a reprogramming.

The speedo, after the swap, is now dead-on. At 65, after multiple tests in different locations (Sierras, central valley, and all around the bay area) it seems to match perfectly to a phone GPS app.

What are the benefits to getting the truck updated to match the config, besides possibly improving accuracy on the guess-o-meter?

Also, range reporting and energy consumption are weird. The % used doesn’t appear to match the 15-minute meter or the odometer / “about” screen. Perhaps these will be fixed if/when I do the update?

That's funny -- I notice my R1 on factory 20's shows it's driving slower 2-3 mph than the vehicle states.

 

[Timothykf]

Have commented on this in past. All OEM R1T with 21’s. Speedo has been INcorrect since delivery. Speed is over-stated on display 2-3 mph at Hwy speed. I’ve always wondered if the odometer is wrong, also. I drive a lot, but never 21k in 10 months! Much less since I drive multiple cars.

 

[jimmyb2]

My R1S on 20" AT tires (12/32" tread left) is always traveling 1 mph slower than the speed displayed on the driver's display (e.g. actual speed 59 mph when vehicle display shows 60 mph). This is true at all speeds.

I measured this with a device that has a 25 Hz GPS which the mfg. says is accurate down to 4 inches although the device itself said it's GPS accuracy was 15 inches at the time I took the speed measurements.

 

[goldburger]

Have commented on this in past. All OEM R1T with 21’s. Speedo has been INcorrect since delivery. Speed is over-stated on display 2-3 mph at Hwy speed. I’ve always wondered if the odometer is wrong, also. I drive a lot, but never 21k in 10 months! Much less since I drive multiple cars.

That's interesting. My odometer also seems high but not enough for me to get pedantic about it and track it.

 

[Dark-Fx]

That's interesting. My odometer also seems high but not enough for me to get pedantic about it and track it.

It was like 5% higher when the R1T first came out but got adjusted back to be closer to 1 mph at any speed. 110 actual max was indicated at 115/116 but now it's 111.

Odometer has always been accurate.

 

[goldburger]

Odometer has always been accurate.

Guess I'm just driving a lot more than I used to because of how awesome my truck is!

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