How do I adjust the speedometer?

Hi, I have a 2003 Tacoma 2.7L Pre-Runner 2WD.

The previous owner installed some beautiful B/F Goodrich tires on the truck and I also put some new rims on it since buying the truck.

The only problem is that (I'm Canadian KPH, not mph) when (for example) I am driving at 100kph as said on the speedometer, GPS apps such as Waze and I've tried with other apps to confirm say I am driving between 114kph and 120kph.

I asked my local Toyota briefly about it and they said nothing can be done, maybe I just need to be more specific.

Either way, how can I go about readjusting the speedometer or telling Toyota about it? Thanks.

P.S. I'm honestly confused they said no because yes it's an older truck but would something like this not be illegal especially considering the fact that my speedometer is as far off as it is? lol.

 

Why would it be illegal if it was then only stock size tires and wheels would be legal to run!

Toyota is not able to solve your problem there is nothing on the parts shelf to install and fix your problem. Be glad the real answer to fix your problem return to stock size wheels and tires

Years ago it was quite common to go to larger tires on our Muscle cars because things were gear driven it was quite easy to build a device to adjust the speedometer to read correct

With Today`s electronic speedometers I would think you could find someone that builds something along thee lines have you looked at all ?? What ever the Canada version to the likes of Summit Racing might very well have something

It is only a matter of recalibrating the signal to adjust to your larger tires

I think for the most people just get used to the fact things are off I know I do and never gave it much thought .

Good luck!

 

How much larger are the tires compared to stock? I run "one step up" (31's) from stock street tires (swap the MTRs when I head off road), and my speedo is fairly close.

You can use the Tire Size Calculator (https://www.tacomaworld.com/tirecalc) to calculate the difference.

I'd also question the accuracy of your GPS. I see you said "apps", so I'm assuming that means you're comparing your speedo to a phone based GPS reading, right? Phones aren't that accurate- Within 5m (16ft). I would bet that this is a larger discrepancy than the tire size. You have to get into some really expensive gear to get within the sub 1m of accuracy range.

You might find this to be an interesting read as well: https://www.tacomaworld.com/threads...n-you-change-gear-ratio-on-your-truck.428495/

 

Great thanks mate

 

yes I've used waze, I have a new touch screen headunit and apple car play and when waze is on it will show my real kpm reading. Other apps meaning random GPS speed apps to check your current speed while driving. I am asking this because I've seen videos of people recalibrating their speedometer.I will try the calculator out though for sure. Appreciate the help.

 

* Within 5-10m. I wouldn't consider GPS speed "real".

You can use a ScanGauge and assign an offset to the mph/kph gauge if you really need to be accurate. Again though, I wouldn't base the % offset on phone GPS (I know people do, but it's wrong) Use the tire size calculator to get the mathematical % and use that instead.

Edit:

This thread covers that:
https://www.tacomaworld.com/threads/how-to-calibrate-mph-on-a-scan-gauge-ii.389330/

It also points out, that the only true way to calibrate is to work from known distances vs the trip computer / dash odometer.

Sorry, it's not as straightforward as you were hoping.

 

Your 1st gen has a gear driven speedo. The gear is located in the side of the transfer case I believe. People have successfully swapped them for gears with different tooth counts to adjust their speedometer. There is a thread on here or ttora that goes in depth about this. Let me try and locate it for you

 

@Empty_Lord

 

https://adventuretaco.com/replacing-the-speedo-gear/

Here's one link, I can't seem to find the full thread on TTora

 

Have you compared the readings of your odometer to the readings of your speedometer? I find that my Speedo is 7% optimistic but the odo is quite accurate. This is intentional to get people to slow down, but it’s super annoying.


I’m just gonna put taller tires on and adjust my mpg spreadsheet

 

Yup finding the the correct speedo gear to swap is the fix here

or a regear

 

I’ve seen some devices mentioned on TW for plugging in for correcting the speedometer can’t remember where.
I would do the math myself. It would be crazy to regear just so your speedometer reads closer, unless you want to regear for other reasons as well.

 

What is the old tire size and what is the new tire size? Was the speedo accurate prior to the change in tire size?

 

Dakota Digital.

https://www.dakotadigital.com/index.cfm/page/ptype=results/category_id=115/mode=cat/cat115.htm

 

For a Harley?

 

Here is one people that make a box to go inline on your speedo cable to recalibrate https://www.yotatech.com/forums/f116/mechanical-speedo-correction-box-install-pics-195986/

 

Don't think any first gens have a cable driven speedo, its all electronic

 

Early Tacomas ('96-'97) did have a speedo cable. The digital ODO was introduced in the '98 model year.

 

Okay, so I found out my old tires were
225/75R15 and my new ones that I have now are 235/85R16 I’ll include a picture of the calculator that you provided me. So now what? I guess I can’t fix it or can I knowing how off I really am?

 

I just installed my yellow Box in my 06 Tundra. It works perfectly but I'm not sure if it works on our trucks. I have 315/70/17 (34.4) and geared to 4.88's. I read a little faster than I should. 72 on the speedometer, 70 on the gps. I might get a little closer if I went to a true 35. I've read up on post #9 but never did more than just reading. Maybe someone can try the Yellow box?

https://www.yellr.com/