Speedometer correction

Hi TW,

If I were to get difference size tires on my taco do you know if the dealership will adjust my speedometer to reflect the correct mpg?

It's not the end of the world.. It would drive me a little insane if my speedometer is off.. Also I'm assuming bigger tires would effect the total mileage number as well right?

 

If you put tires on that are 1" taller than stock then your speedometer will be dead on.. Stock is 265/70/16 or 265/65/17, so if you go with 265/75/16 or 265/70/17 speedometer will be exactly right.

 

So what you're saying is from the factory the speedometer comes inaccurate?

 

^Yes. The speedometer over-reports by default. Spillover from some European regulation.

The odometer is reasonably accurate. So if you get larger tires, the odometer will register fewer miles than actual. Keep this in mind when you calculate fuel economy.

 

Can anybody else attest to this? So my trd sport has 265 65 17 oem tires and wheels and if I go 265 70 17 the speedometer is right on the dot? First time I've heard something like this

 

Thats what Ive always heard too

 

But.....the dealership would be able to change that for you right? Or another auto place? I've got 285/70/17 and I'm off by a few mph.

 

I saw this in the trucks menu for recalibration when you get new tires. I run stock, but maybe someone can verify if this actually works. Looks like it uses the GPS.

Setup>Navigation>Detailed Nav Settings>Calibration>Tire Change

 

Holy crap! If that really works..these trucks continue to surprise me

 

It seems that for many Tacoma owners on this site that their speedo becomes more accurate when larger tires are installed. I however have had the complete opposite affect on my 2012 sport. When my speed is dead center between 60 & 65 my GPS says I am doing 65 and when my speedo is at 65 my GPS says I am doing 68. I did check my speed prior with factory size tire and currently with my Michelin LTX ms2's 265/70r17. I found the factory size to be very accurate whereas the larger tires to be very inaccurate. And it also seems to me that the faster I go the more inaccurate it becomes. To test the speed I have used 2 different types of Garmin car GPS and 1 Garmin handheld all with the same results...and again I don't mean to question anyone but my speedo is very inaccurate. OP It's extremely annoying especially because I do a lot of highway driving.

 

Download a gps app to your phone and try it with stock tires vs. 1" taller tires and you'll see it's dead on with speedometer in the truck

 

any way to correct the digital mph and the analog mph which is off by 1. my ocd....

 

Use a gps app to find your actual speed compared to your displayed speed. Buy a Hypertech speedometer calibrator and input the correct measurements. I've never heard of being able to adjust your speedo from your entune unit.

 

I believe that the calibration through Entune is just to adjust the gps location somewhat and Not calibrate speedometer for taller tires.

Edit: Actually it adjusts the compass

 

My digital speedo is 100% dead on. The analog is off by around 2mph.

 

System tolerance is the reason. The middle of the bellcurve is set to ~3 mph over-report, so outliers like your truck don't under-report.

Not sure why some people care about 2-3 mph error on the speedometer. If the purpose is to save gas, it's better to set your speed based on engine rpm.

 

Mixed responses.. 265 70 17 it is!

 

This is interesting. For the past few months I thought I was doing 70 on 485, when I GPS tested turns out it was 67. I have stock tires so they are undercalculating speed. Been going a little "faster" since then.

 

I’m on 285/70r17 and we have a speed radar and my speedo is right on the money accurate.

 

I think I am experiencing similar. But the analog is 1mph off. I havent tested with GPS but every speed sign I pass has me going my digital speed but analog says I am going 1MPH slower.