Speedometer Calibration

Do speedo calibrators adjust the odometer also? I have mine calibrated to adjust for bigger tires (285/70r18) but have always wondered if it actually adjusts the odometer and If I should be adjusting vehicle maintenance accordingly.
Thanks

 

The odometer is run off the speedo, but adjusting the speed will not retroactively correct the odometer. It will just make any future mileage added be accurate.

 

Okay that’s exactly what I needed to know. I’ve had mine calibrated for awhile and never knew if it was actually functional.

 

^^^
What that guy said.

 

which one do you use? I did not know this, and need to get one now lol

 

I got the Rough Country one. You actually use one of the bigger companies software to calibrate it which leads me to believe its like a Costco type of product.
Calibrator:
https://www.roughcountry.com/speedometer-calibrator-90017.html
Software:
https://www.roughcountry.com/speedcal-update

 

You had to recal with 285/70's? Mine is only off by 1 mph.

 

Yes mine was about 5-6mph off. Calculated by Waze and my GPS on my Uniden radar.

edit: it was more noticeable at highway speeds how off it was.

 

I have the 285/70/18, never thought of calibrating my speedo. Each time i pass the school zone they have a radar , and it matches both the same.

 

It's not off by 1 MPH. It's off by a percentage. It may be a small percentage that you only notice as 1 MPH at a speed, but it's not 1 MPH through the entire range. The faster you go the more it'll be off.

 

My Tundra-fu very is low when it comes to speedometer calibration.

On (maybe more) navigation radios there is a GPS option to recalibrate based on a changed tire size. I thought this also updated the digital speed display in the cluster for +2018 trucks. If not, how is it used?

 

That explains why I use to do 80 it would read 75. And 35 it would read 33-34ish. Always pissed me off. I’m just glad to know my maintenance intervals are being tracked properly.

 

I did 80 or so on a road trip last weekend and is was only showing 1 mph difference at that speed.....using Waze.

 

HyperTech makes the Speedo Calibrator.