People running bigger tires, are you just not recalibrating your speedo?

I spoke to the dealer about this and they haven't a clue how to recalibrate the speedo for larger tires. Are you guys just running blind or did you recalibrate it somehow?

 

Blind, but I am always the guy in the slow lane anyhow. MPG's

 

Never got mine calibrated.. on a 182 mile trip my truck says I went 175 miles so its not off by too much

 

check out "speed o healer", search toyota 120 forum its perfect right to the gps. have had mine for four years , 3 sets of tires (different size), two regears, perfect endless adjustablity .

 

How big of tires are you talking? I have 265/70/17 and they are pretty much dead nuts on. verified with a gps while watching my speedo. the factory calibration has a built in tolerance that seems to error on the slightly faster side, so the slightly larger tires actually make it perfect.

If you go really big, well then you might have to look into a way to calibrate, or just use a gps and know how far off it is.

*If you have a smartphone, just get a gps speed app.

 

I'm admittedly more concerned about the odometer being accurate, and the speedo being off clearly has an effect.

I'm looking at 33x12.5x17 or 35x12.5x17s.

 

I'm running 285/75's and I downloaded a gps app on my iPhone. Speedo shows 55mph gps shows 60. I checked my Garmin also with the same result. Faster you go the more off the speedo is too.

 

Never calibrated mine. It's not much difference. For example with mine. If I'm going 20 mph on my speedo, I'm actually going 21 mph. 40 is about 42. 70 is 74/75. I don't remember the math exactly, but it's not much difference.

 

dont care i have a garmin that tells me my speed mine is about 3 mph off at 30

 

I'm running 285/75/16s and my speedo isn't off at all...maybe a little but not enough to notice.

 

I went up from 265/70-16's to 265/75-16's. Only a couple MPH diff, so I didn't worry about it.

 

The Hypertech programmer is really easy to install and the software is extremely basic to use you simply enter in your original tire size and new tire size and hit enter. You can leave the USB cable installed and coil it up under the dash or in your change pocket etc and reprogram it as your tires wear out IE: most 35's are actually 34.5 - 34.8 new and when they are worn out they are 33.5.

The Taco transmission and shift points are not impacted by the re program like most US trucks so unfortunately there is no gain other than your speedo being accurate.

 

I'm lifted 6" and on 35's, and mine is off like a mother... It's about 10% I think. So when I reads 70, my truck is going like 77... And when I'm going 50, my truck is going like 55... But it doesn't bother me.

 

There are speed traps throughout my area with digital speed readout's and mine is off by like 3 mph

 

I rely on my GPS unit

 

Which hypertech programmer did you buy? I've been looking but none say they are available for my truck...

 

Pretty much.
I run the same and at 60mph I'm off 4mph per my GPS.
I think that equates to 9 extra miles per 100 miles.

 

It is on the Hypertech site :

In-Line Speedometer Calibrator - Part #730107

 

Oh awesome I found it! So is there just a plug in under the dash? (don't wanna go look right now ) Thats how it is on my mom's jeep and my dad's ram...