Speedometer miss calibration

My truck has the Spec one pack.
I was ticketed for speeding. Come to find that my speedometer was never calibrated from the dealership after dealerships modifications had been made. Speedometer is off by 6-7 miles an hour. Dealership says they can't fix. I believe that it is a result of tire size. As I understood tires should be a 16 inch rim size. When upgrading to spec 1. The tires installed on my truck is with a 17 inch rim size.
Does anyone have this problem? And what can I do? Dealership should be responsible!

 

It's not the size of the rim that matters, it is the OD of the tire. Give tire specs, and we can give a formula to calculate the margin of error.

 

Wow, 6-7 is quite a bit. Use a GPS app on your phone to nail it down.

G.

 

What size is your tire??

 

not really. in my jeep i went from stock 29's to 32's which is about 10% more and thats what my speedo was off by, so at 60-70 it was 6-7 mph off. need to know what tire size the dealer put on though to give a final say.

 

Hypertech makes a speedometer re calibration module. https://www.tacomaworld.com/threads/hypertech-spedometer-calibrator-on-2017.456351/page-2
It works very well.

 

What’s a spec one pack bro?

 

This.

Also, wtf is "Spec 1"..?

 

Has to be some dealer garbage add-on's. Probably a spacer lift kit, bro wheels/tires, blacked out emblems...all to the tune of an extra $8k.

 

Easiest way to remedy this... download a speedometer app on your phone. See what it reads when your speedometer reads 35mph. Then see what it reads at 55mph. Then see what it reads at 75mph. The speedometer error will increase as you go faster in the truck.

My guess is you’ll be 2mph off at 35mph. 3-5mph off at 55mph. And 6-7 off at 75mph. I know it’s not a fix, but it’ll help you avoid the law until you find a fix.

 

and speed you were clocked vs. speed you saw on your speedometer. If it's 6-7 past what you saw, I bet you were running 70-75mph correct?

interesting point. if due to dealer installed mods, I would at least inquire about payment.

 

Agreed.

 

yep. Show up in court, drop the math like it's hot ... and be sure to bring a cheap mic to drop soon after (actually don't, this might hurt you. )

 

Intrigued on this spec one package plz tell more

 

Its the package before SPEC 2.
Duh

 

Blame the dealer for the ticket!

Worse fuel mileage?! Have the EPA phone the dealer!

Dude, get over it, it's part of having a modified vehicle. I STRONGLY doubt it's out that much, and you'd have a difficult time proving that.

Going from stock 31 to 33" tires at 60mph is 4mph difference, hardly noticeable, and not worth calibrating over.

So if you were 10mph you can blame the tires, not the dealer for 4mph of that ticket. Get over it.

 

Hey where do we get the Spec 1 mod

 

@raven543 dont mind our jackass reaponses. This is the norm on here.

Malibu7 posted the only working solution(as of right now) from hypertech to recalibrate the 3rd gen speedo. The dealer should know about this if the do spec 1,2,3,4 etc kits. If they don't, find another dealer.

 

Is it like Spec ops? night vision fold down visors?

 

Buried in the entune menus there is a calibrate tires button. I clicked this one day and it said beginning calibration. After driving around for a while mine seems to be spot on with what my gps readout is.

It’s been a while since I’ve done it but I believe it’s in the vehicle customizations section