speedometer calibration

[FORDPWR]

My speedometer is slow by 10 mph and I'm only running 35s. I choose the 34.5 tire option with the ez lynk and nothing changes. Any idea on what's going on and will this affect my shift points?.

 

[stroker2]

interesting. My truck is the opposite. I have 35s on and i had to choose the 31.5 tire option in order for the speedo to be correct

 

[redneck1]

Dunno if it'd work, but some dodge guys have had good luck putting in a different tire size, flashing your tune, then turn around and do it again with your tire size you want.

Oddly enough, my ez lynk has never given me the option even after updating... But my tuner has it in the tune add ons and it's 1 mph off with 35 tires..


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[FORDPWR]

How far was it off before you changed the tire size?

 

[FORDPWR]

I changed my tire size to the 31 option and speedometer still off by ten from the auto agent app but if off by 15 on gps. Wtf?

 

[slc6oh]

same issue for me kinda,.... auto agent app and gps match and are 3-5mph slower than whats reading on the dash.

ive got a Canada truck,(130mph speedo) so I just kinda figured it was something to do with that.

 

[Jgon08]

I had the same issue with my 13 dash was off around 12 mph took it to ford and they reset it no problem. Said by law they are aloud to be off 3 mph. Thats what I was told not sure if that’s true or not. But I’d try ford or a friend with forscan can probly do it aswell.

 

[andrewtac]

I think they are set to run 3mph fast (you are slower than what you are reading). There is a pid (I think vss on torque) that shows actual speed. That is all based on putting the correct tire size on. I went to the next size to make my Speedo read actual (used forescan) and have since went back; I believe everything else (miles on odometer, DTE) that uses speed or miles uses vss and I didn’t want everything else off.

 

[ckrueg]

I think they are set to run 3mph fast (you are slower than what you are reading). There is a pid (I think vss on torque) that shows actual speed. That is all based on putting the correct tire size on. I went to the next size to make my Speedo read actual (used forescan) and have since went back; I believe everything else (miles on odometer, DTE) that uses speed or miles uses vss and I didn’t want everything else off.

I noticed this as well. With my 35s I calibrated the tire size to max factory size which is about 1 inch smaller. My Speedo is right on but everything else is a bit off.

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