Speedometer Adjustment

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OffKamber

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Any aftermarket options to fix speedometer after going to larger tires? Running 285/75/17 KM2's and noticed that it's 5-6 MPH off based on cell phone GPS (tried 2 different apps) when in the 75-80 MPH range. And I'm usually trying to drive 79 MPH on the freeway... which means I will be getting tickets unless I fix this issue...

P.S. I have an Alpine 309 Halo9 ILX-F309 but don't see an option to adjust it there as well... it seems to be reading from factory dash so it's useless as well...
 
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Only option is common sense. do the math and watch your speed. One would think 10 years of the 5th gen someone would have made one, but nope
 
I think it’s because it’s just too easy to look down and say oh the speedometer says 70 I’m doing 75. I’ve got 35’s and it’s only about 4-5mph off at that speed.

I just don’t think there’s a huge need for it so no one ever really brought a product to market


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I seem to recall reading in a past post that there's a speedo sender gear change required. I'll see if I can find it.

On my Ram truck, it was a simple ECU reflash. Punch in the tire size in the menu and it made the correction automagically. Wouldn't that be cool if it were that easy?

Edit: The speedo sender gear is on older vehicles. The one I did find in search used a Tacoma wheel speed sensor and an electronic witchcraft box. Still looking...

2nd Edit: Here's the discussion I read about with the "magic box". Doesn't seem like it's too difficult to install. Just takes a bit of time to disassemble the dash, although you could probably catch the wheel-speed signal elsewhere if desired.

Speedometer and ABS Adjustment? - Toyota 120 Platforms Forum
 
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The problem is having multiple vehicles... one day I drive 79 in my other car, one day I get into the 4runner and forget to do the math cuz I was used to looking at the Speedo on the other car...

All the research I’ve done seems to say that the Speedo healer won’t work on 2015 and up models due to different computer programming on 4runner.

I’m Not superior with electronics so I didn’t want to start experimenting yet.
 
Just saying...
 

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Have you confirmed actual speed vs the speedometer with one of those radar speed limit signs? I doubt your phone gps is correct.

My 2019 speedometer is accurate with a 33" tire. Lots of people on here report the same finding with their trucks on 33"s. With the oem 265/70R17 tires, the speedometer was off and showed me going faster than I actually was. When it showed 70 mph I was actually doing about 67.

265/70R17 = 31.7" diameter; 656 revs/mile

255/80R17 = 33.1" diameter; 628 revs/mile

285/75R17 = 33.9" diameter; 614 revs/mile

I'm thinking your speedometer should read a little over 2% slow with those tires, so figure you're going 79 mph when it reads 77.
 
The speedometer is actuated by the ABS sensors in the 5th gen. Pretty sure the only way to do it would be to fit 4 Speedo healers, 1 for each wheel sensor.
 
Tuco S. said:
Have you confirmed actual speed vs the speedometer with one of those radar speed limit signs?
Click to expand...

Radar speed limit signs are not all that accurate. I've seen them give readings as much as 5 MPH different. Most states require any radar instrument used for citations to be accurate, i.e. the instruments must be calibrated from time to time. Radar signs have no requirement to be calibrated; they are for informational purposes only.

Photo radar used for citations have been discontinued in some states because it is easy for a good lawyer to prove the photo radar was wrong (not calibrated), picked up the wrong car, or other problems.
 
fkheath said:
Radar speed limit signs are not all that accurate. I've seen them give readings as much as 5 MPH different. Most states require any radar instrument used for citations to be accurate, i.e. the instruments must be calibrated from time to time. Radar signs have no requirement to be calibrated; they are for informational purposes only.

Photo radar used for citations have been discontinued in some states because it is easy for a good lawyer to prove the photo radar was wrong (not calibrated), picked up the wrong car, or other problems.
Click to expand...

Ok then, another way to check your speedometer is to choose a route with a known distance, say 20-30 miles or so, then set your cruise control and time how long it takes to drive it. The longer the route, the less chance for error. Then come back and report your findings.
 
hypertech and roughcountry offer something for the tundra and tacoma, wonder how different it is for the 4runner.
 
rayofsi said:
hypertech and roughcountry offer something for the tundra and tacoma, wonder how different it is for the 4runner.
Click to expand...

I checked and as of 2023 both companies do offer products for the 5th gen 4Runner. The Hypertech is plugged into the OBDII port and apparently recalibrates the ECU. The Rough Country looks like it is installed in-line behind the instrument cluster and stays connected.
 
beingnotdoing said:
I checked and as of 2023 both companies do offer products for the 5th gen 4Runner. The Hypertech is plugged into the OBDII port and apparently recalibrates the ECU. The Rough Country looks like it is installed in-line behind the instrument cluster and stays connected.
Click to expand...

The hypertech also installs behind the cluster and stays there. I have one but have not installed it yet as i am still only running 33s.
 
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