Speedometer Calibration

I just recently purchased a 2015 Tacoma with a Toytec / Old Man Emu 3” lift. 285/85/17 tires. From checking the vin # with Toyota and it looks like the Tacoma came with P245/75R/16’s. The tire calculator shows that the speedo is waaaaay off. Does Toyota do speedometer calibrations ?

 

I don’t believe there is a way for the dealer to do it. Also do you mean a 285/70/17 the tire size you put down is 36” and no way that would fit with a 3” kit. I run 285s and my Speedo is dead on as they are usually off from the factory.

 

Yep, you’re right‍♂️ Fat fingered that one! LT285/70R/17. I’ve tested it against two other vehicles and seems to be quite a ways off at 65, just wanted to make sure it was close.

 

a simple quick check is to use the mile markers on the highway. Go 60 and it should take 1 minute between markers. Then you’ll have a very good idea.

 

That makes too much sense! Have no idea why I didn’t even think of that. Thanks

 

I have a Highway patrol officer that lives in my neighborhood. So I had him radar me. So that’s how I know mine is dead on.

 

Sometimes it’s the simple ideas we forget about.

 

That could be handy. And a great way to check it.

 

So is there no way to recalibrate a Gen 2 Tacoma if it is off? Too used to tuners on diesels, enter the distance of one tire revolution, and recalibrated!

 

I believe there are some aftermarket ones that you plug into the OBD2 port. But I’m not sure if you can actually change the setting in the factory computer to permanently correct it. I’d do the hwy check. You might find out its not as far off as you think it might be. A lot of the speedos are fast from the factory so when you go bigger tires they end being pretty close to being right on.

 

That will be the first step for sure. Once upon a time, a guy could just change the gear on the speedometer cable in the tranny. Giving away my age now I assumed that if anything was off, that someone had a means of recalibration gore changing shift points, etc.

 

Yep. I remember those day. Just switch the little gear at the tranny housing. Fixed!! On our 2015 they use the right rear wheel sensor for the speedo.

 

Check with a GPS. Chances are that you MIGHT be 5 mph off at 70 mph. At slower speeds not enough to worry about. Most Tacoma's are off from the factory and adding bigger tires often corrects the speedometer. Mine said 70 mph and GPS said 68 with factory tires. Going up to 265/75/16's resulted in both reading the same.

Plug in numbers here Remember tires don't stay the same size. As you drive they wear down and get smaller so you're never going to get the speedometer exactly right all the time. By the time you wear out a set of tires they will be an inch or more smaller. Roughly the same as going down one tire size.

 

Using the gps may be another easy way to verify. Hard to believe the speedometer on the Tacoma is that far off. Using the link you posted, the difference is significant, or at least enough for a ticket in Colorado!

 

Until you do get it recalibrated, use this to figure out your speed on dash vs actual. Looks like it's a 4 mph difference depending on speed. The faster you go the more it's off.

 

Do you have any suggestions for recalibration? I’ve seen a couple aftermarket mentions on threads, but, nothing that sounds great.

 

Original Tire Size, New tire size,
245/ 75R 16. 285/75R 17

Speedometer Reading 65, actual speed would be 72.17. Any change in shift points at that difference, or under load. Lots of questions keep coming up, as I think about it

 

https://m.youtube.com/watch?v=7n6DEYqVDEY

Here's an option

 

I've heard of this product:

https://www.roughcountry.com/speedometer-calibrator-90043.html

I only upsized by 1 inch diameter which is enough to do the math in my head. (60=62, etc) but it might be worth it for people that go larger.

 

You might have done it wrong there lol. 285/75r17 is a 34 inch tire. You're going with 285/70r17 (33") right?

Just hop on the highway with google maps running, it will tell you your speed via gps and then compare it to your dash. It shouldn't be off by much. Sorry I dont have any advice on what to use to calibrate, I've never done it before.

Do the google maps thing though, get up to 65 on the dash and compare it to what google is saying your speed is.