Are the speedo's different??
- Thread starter eplanajr
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brian2sun
Elite Member
The tire diameter is the only thing that will throw off the speedo. Rim size doesn't matter. For instance a 285/75/16 is the same size tire as a 285/70/17 and both would throw the speedo off the same amount although the rim size isn't the same.
Most of our trucks "say" they came stock with 15s on the door sticker, but the vast majority of 3rd gens were actually sold with 16s. In most cases, the dealers upgraded the wheels and tires before the original sale of the truck. I doubt much if any of the dealers actually calibrated the speedos, but the difference in size between the "original" 225/75/15s and the "upgraded" 265/70/16s is minimal as far as the speedo is concerned.
Most cars aren't totally accurate from the factory anyways. I've heard that most cars leave the factory with a speedo that reads 1-3 mph faster than actual speed. I think this helps keep people under the speed limits and also makes your mpgs look better.
Anyways, in your case, the difference will be too small to worry about calibrating it. I really didn't notice a difference until I went to 33s.
Most of our trucks "say" they came stock with 15s on the door sticker, but the vast majority of 3rd gens were actually sold with 16s. In most cases, the dealers upgraded the wheels and tires before the original sale of the truck. I doubt much if any of the dealers actually calibrated the speedos, but the difference in size between the "original" 225/75/15s and the "upgraded" 265/70/16s is minimal as far as the speedo is concerned.
Most cars aren't totally accurate from the factory anyways. I've heard that most cars leave the factory with a speedo that reads 1-3 mph faster than actual speed. I think this helps keep people under the speed limits and also makes your mpgs look better.
Anyways, in your case, the difference will be too small to worry about calibrating it. I really didn't notice a difference until I went to 33s.
Nelsonmd
New member
I believe that federal law requires speedo's to be within 5%; not due to speed, but due to reading mileage for warranty and sale purposes. That said, I am not sure if that still applies to a dealer putting optional wheels on them.
brian2sun
Elite Member
I'll buy that. And if 5% is the standard variance allowed, than that's probably why most dealers probably didn't bother recalibrating the speedos. The difference between 225/75/15s and 265/70/16s has gotta be less than 5%. My speedo/odo are about 9% off (going from 30s originally to 33.5s currently). I got 9% based off my '05 Honda CR-V compared to my 4runner.
SKIDMRK
New member
I have a friend that runs a speedometer shop in Tacoma and they have an in ground set of rollers (not full dyno) that they use to do speed checks. Had him throw my '00 runner on there to see what it read with the 265/70/16's on. It's 3mph off at 60.
Meaning that if the speedometer says i'm doing 63, i'm actually only doing 60.
Meaning that if the speedometer says i'm doing 63, i'm actually only doing 60.
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brian2sun
Elite Member
Wow, that means if yours had 225/75/15s on it originally, the speedo would have been even more off. In your case if you went to bigger tires like 265/75/16s, your speedo would read almost perfect.
99runnerwa
New member
SKIDMRK. What shop does he work for? my speedo is about 10% off. when i am going 66 it reads 60. i havent really been actively looking for a place to fix this but figure if some one local can correct it id be all for it. Also a little off subject but......where is the speed sensor on our rigs? i have the sr5 with an auto transmission. I had assumed that after going from stock gearing to 4.56 that my speedo would be close to correct but there was no change at all. comparing the RPMs to the actual speed i am reasonably certain that the gear place didnt screw me and put the wrong ones in. but it does confuse me.
SKIDMRK
New member
My thoughts exactly. going to a 285/75/16 like i plan to would be only one-two off in the other direction. close enough for me.
He's at Tacoma Speedometer off of Steel St and Highway 512 in Lakewood.
Tacoma Speedometer - Home
Regarding correction, i believe the only way to do it is with a electric conversion box similar to what dakota digital and a few other companys sell. Not sure what installers prefer tho. Heard some good and bad about wiring them in.
Universal Speedometer Signal Interface
99runnerwa
New member
Thanks man, ill have to get a hold of them.
SKIDMRK
New member
no worries. if you talk to eddie or dennis, tell them the "brown kid" sent you and maybe next time i'm at the shop i wont get rockstar poured down my buttcrack when i'm working on a suspension. a drive from lakewood to bothell with a sticky ass is no bueno. :bash:
Garage Guy
New member
ChildrenOfBodom
Moderator
There are definitely some different speedo calibrations, at least between motors.
The speed sensors are different on the 4 cylinder models, the cluster will convert the speed signal for the ecu. Differently geared transmissions in the 4cyl vs the V6 have different sensors and/or different calibrations
I get confused when I get into the ABS trucks and the speed sensors and ahsidfgnfighrejtg
The speed sensors are different on the 4 cylinder models, the cluster will convert the speed signal for the ecu. Differently geared transmissions in the 4cyl vs the V6 have different sensors and/or different calibrations
I get confused when I get into the ABS trucks and the speed sensors and ahsidfgnfighrejtg
IanB
New member
That's the exact link I was going to post, comes in very handy!
Nelsonmd
New member
I think someone is a little bit obsessed with feces...
brian2sun
Elite Member
Wow, I thought a 225/75/15 was a 29" tire, but it's really a 28". So yeah, maybe the dealers did calibrate the speedos when they upgraded. If not, I suppose it would have been technically illegal not to.
