Speedometer Calibration Question

See that's what I was really wondering... My 2nd gen has the stock tires on it, and with GPS it APPEARS to be dead on with the speedometer, I am simply waiting until the stock tires need to be replaced to upgrade to some Falken AT tires of the before stated size. I was just thinking about MPG, odometer reading and speedometer readings with the new tires. I know some MPG will be lost. But I do long road trips sometimes and was worried that the long distance might screw up my odo readings.

 

My understanding is that the odometer pulls its info from a gear the transmission independent of the wheel speed sensors. Please correct me if I'm wrong. So if my understanding is correct, using a product like the Hypertech Inline Calibrator will not affect your odometer reading. While waiting on my calibrator to show up, I was tracking my speed/milage with my GPS unit and even though the MPH was way off, the odometers in both my truck and in the GPS unit were reading the same. I put a little less than 1k miles on while waiting for calibrator.

-J

 

My speedo is off approx. 3-4 mph.. I am not going to adjust it since it is my free get out of a ticket. In VA if you can prove you speedo is off you can get out of the ticket with a improper equipment.

 

I installed the Hypertext in-line speedometer about a week ago. So far it seems to be working as advertised. Programming the unit is simple enough; you can select generic tire sizes or specify the diameter of your original and current tires. I've pulled the calibrator several times to adjust the numbers. I've currently got the difference between the truck's speedometer/odometer and a Garmin GPS to within 0.05%. (Would make it a lot easier if had a laptop so I wouldn'the have to tear the dash apart every time I want to reprogram the unit.)

The stock 2015 TRD Sport tire size is 265/65-17. I moved up to BFG K02 265/70-17 three years ago which resulted in about 3.2% error compared to the GPS. Two months ago I moved up to 285/70-17 K02s and had about 7% difference compared to the GPS.

Is the Hypertech unit worth the cost? For me it is. I tend to have a heavy foot and seeing the correct speed on the speedometer helps keep my speed down - well, somewhat anyway. It also helps with tracking distance and fuel calculations without having to go back and forth from the speedometer/odometer to the GPS or the Android tablet I use with Gaia GPS.