Inaccurate speedometer

[Sugarloafer80]

Well known fact to avoid legal issues with people actually going FASTER than speedo indicates and getting things dragged into court is to set speedo for largest potential tire fitment...within reason. I bet you go up an 1inch in OD and speedo is probably spot on. Toyota speedos even on my Lotus always indicated 2-3mph faster than actual speed. Sounds like 82 is the new 80!

 

[RoundRock_Cruiser]

Same issue here, i have the 20inch premium wheels and the speedo shows 3-4 mph faster than Waze, also noticed the difference when passing the construction zone speed check doohickey. if the speedo is off does that mean odometer is off?...just heard my internal voice say "google it!"

AI Overview

If your speedometer reads faster than your true speed, it's a common safety feature designed to prevent drivers from exceeding the speed limit and is often due to factory calibration or larger-than-original tires. While modern odometers are separate and generally accurate, the over-reading of the speedometer is often independent of the odometer, meaning your mileage is likely being recorded accurately. However, if the cause of the speedometer error is a change in tire size (like installing larger tires), both the speedometer and the odometer will become inaccurate by the same percentage, with the odometer overstating the actual distance traveled.

i guess i should verify the miles with the tripo and a Waze navigated trip to confirm.

 

[cccbryan]

Same issue here, i have the 20inch premium wheels and the speedo shows 3-4 mph faster than Waze, also noticed the difference when passing the construction zone speed check doohickey. if the speedo is off does that mean odometer is off?...just heard my internal voice say "google it!"

AI Overview

If your speedometer reads faster than your true speed, it's a common safety feature designed to prevent drivers from exceeding the speed limit and is often due to factory calibration or larger-than-original tires. While modern odometers are separate and generally accurate, the over-reading of the speedometer is often independent of the odometer, meaning your mileage is likely being recorded accurately. However, if the cause of the speedometer error is a change in tire size (like installing larger tires), both the speedometer and the odometer will become inaccurate by the same percentage, with the odometer overstating the actual distance traveled.

i guess i should verify the miles with the tripo and a Waze navigated trip to confirm.

I would have thought that with the larger 20" wheels that your speedometer would be spot on. My 18" wheels record about 2mph faster than actual on highway.

 

[Sugarloafer80]

I always thought Bronco was the ride Quality........sure was on the 80s models

 

[jedyxu]

I’m on 285/75/18 and the speedo is still about 3% slower than what the GPS reads. However, on the odometer, it reads about 7% less than the actual traveled distance. So weird that they get their readings differently. Longer warranty for me!

 

[Sugarloafer80]

If a 285/75/18 is 34.8in OD you SHOULD be doing an indicated (Speedo)60 when you are doing something like 62 on GPS. At almost 2 more inches, even if you were 2mph off, that should be more like a 4mph correction to the opposite. Taller tire, less revs per mile therefore, slower indicated speed. I find on most vehicles a 1/2 inch of OD equates fairly well with 1 mph. So 2 inches should be ~4mph. Mathematicians chime in please.
Odometer needs to be calculated off a measured mile and precise GPS speed. Ideally best to do over at least 2 miles. I used to do this all the time when I was a kid for driving mental calisthenics.

 

[cccbryan]

Since I have owned my LC the speedometer has been about 2mph slower than the Waze app GPS speed. Interesting thing today when I was on highway the speedometer was spot on matching the Waze GPS speed. I know the Waze app was recently updated but I wouldn't have thought that would have anything to do with GPS speed. Wonder if Toyota did a system update that would have changed something? I never gotta an update notification from Toyota so who knows. All I know is it's accurate now. Anyone else notice that theirs is accurate now?

 

[WeGo250]

Kind of a separate speed issue, but when the adaptive cruise control (only way I use it) is active, the vehicle is always 1 mph slower than the setting, and no that's not because someone is in front of me etc. lol

 

[Altitude]

There would predictably be about a 2MPH discrepancy at 60MPH between 245/70 and 265/70 tires based on differences in rotating diameter. It’s a bit surprising to me that Toyota doesn’t recalibrate.

 

[Altitude]

Kind of a separate speed issue, but when the adaptive cruise control (only way I use it) is active, the vehicle is always 1 mph slower than the setting, and no that's not because someone is in front of me etc. lol

Same for me.

 

[gteech]

Kind of a separate speed issue, but when the adaptive cruise control (only way I use it) is active, the vehicle is always 1 mph slower than the setting, and no that's not because someone is in front of me etc. lol

I don't use the adaptive control. I use the regular cruise control. My setting is always lower than what I put it at.

 

[Altitude]

I would have thought that with the larger 20" wheels that your speedometer would be spot on. My 18" wheels record about 2mph faster than actual on highway.

This is a really helpful website that can compare tire sizes and output a bunch of data including Speedo differences.

265/60/20 and 265/70/18 tires, for example, are so close to the same diameter that Speedo difference between them is less than 1MPH at 60MPH.

Tire Size Calculator

The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.

tiresize.com

 

[DubDub]

This conversation becomes more interesting when you consider that you are disproportionately reporting more mileage on your odometer than actual miles driven. Also, by product of reporting a greater distance traveled than actual, it is reporting a higher mpg efficiency than you are actually getting.

I talked to my dealership about it and they claim there is no calibration possible. I’m trying to forget about it unsuccessfully. Everyone has their complaints, but this one is the only one that truly makes me upset with the LC.

 

[cccbryan]

This conversation becomes more interesting when you consider that you are disproportionately reporting more mileage on your odometer than actual miles driven. Also, by product of reporting a greater distance traveled than actual, it is reporting a higher mpg efficiency than you are actually getting.

I talked to my dealership about it and they claim there is no calibration possible. I’m trying to forget about it unsuccessfully. Everyone has their complaints, but this one is the only one that truly makes me upset with the LC.

From the research that I have done (limited at best), it appears that the odometer mileage isn't connected to the speedometer and from what I understand they are two separate devices. Like you, I was concerned with inaccurate mileage as well but it appears that with the electronic speedometers and odometers that they operate separately.

 

[DubDub]

From the research that I have done (limited at best), it appears that the odometer mileage isn't connected to the speedometer and from what I understand they are two separate devices. Like you, I was concerned with inaccurate mileage as well but it appears that with the electronic speedometers and odometers that they operate separately.

I sincerely hope so, but the nerd in me is going to have to run a practical test now. Given that both speed and distance are computed directly from rotations/time, I’m less than optimistic.

 

[misfits9095]

The MPH being off really annoys me with this car. My car is slower by about 2 - 3 MPH based on radar and GPS measurements. It's very odd that you can't calibrate the speedometer on this vehicle. My old Jeep wrangler could be adjusted at the dealership or using a diagnostic application on my phone. It seems silly that you can't do this on a Land Cruiser given some folks will run bigger tires to offroad.

 

[Sugarloafer80]

Name me ONE vehicle you can calibrate the speedo on from the factory? I know of ZERO. It's really not that hard. Ya wanna do 80? Set cruise to 82. There have been aftermarkets ways for years. Been doing this on cars for 40++ years.

 

[misfits9095]

Name me ONE vehicle you can calibrate the speedo on from the factory? I know of ZERO. It's really not that hard. ewanna do 80? Set cruise to 82. There have been aftermarkets ways for year. Been doing this on cars for 40++ years.

I did name one car... The Jeep Wrangler. The current Jeep wrangler can have it's speedometer calibrated at the dealership for a fee or you can use an app on your phone called JSCAN to adjust the speedo based on the dimensions of your tires. I'm shocked you weren't aware given your 40++++ years of experience. New cars are rolling computers and some allow you to adjust and adapt characteristics of the car through software. Feel free to look into it.

 

[DubDub]

Yeah, I’ve had Wranglers, Silverados, and even my 2015 Taco recalibrated. There’s 3 off the top of my head based only on personal experience. Hell, I had the speedo on my R1 recalibrated after swing arm and heavy tire mods.

Is the head math easy? Sure. Odometer reporting is the most important thing about it to me… can I list head math numbers if/when reselling?

I too have been doing it for some decades, so it seems crazy to me that you have zero knowledge of it being done in 40+++++++ years of experience.

 

[Sugarloafer80]

So you don't have the app /program that does it by yourself? You need your dealer...That is not what I was referring to. Changing the speedo gear was a thing also and actually quite easy. Most of my background with this was sports cars, not off roaders. I am more into speed than dirt. Totally different world.I was specifically referring to a car that you could reprogram within itself. I
Superscips, Powerchip, Supertune, Diablosport......
So my statement stands 100% correct. No vehicle I know of has the ability to let trhe OWNER calibrate the speedo with in its onboard programming...on his or her own. Hope that was clear enough.
It is obvious a lack of clarity exists. I saw so many posts with completely irrelevant comparisons of wheel diameter, section width and aspect ratio grossly MIS compared, I threw that out there. Aspect ratio and section width have zero to do with speedo calibration. Only 1 number matters....OD.

Yeah, I’ve had Wranglers, Silverados, and even my 2015 Taco recalibrated. There’s 3 off the top of my head based only on personal experience. Hell, I had the speedo on my R1 recalibrated after swing arm and heavy tire mods.

Is the head math easy? Sure. Odometer reporting is the most important thing about it to me… can I list head math numbers if/when reselling?

I too have been doing it for some decades, so it seems crazy to me that you have zero knowledge of it being done in 40+++++++ years of experience.

Apparently you misunderstand....no surprise.