I just bought a 2001 F150 Screw 4x4 and it is on a 6" fabtech lift on 20" rims with 37" toyo mud terrains. I guess due to the large tire size , when im going 45mph my speedo says im doing 50, so im really doing 5 under whatever the speedo says im doing.

How do I fix this problem and calibrate it? Do I bring it to ford? I have a superchip programmer and i've heard I can do it from tehre but I havent tried yet because i wanted to get an input from what you guys think.

Thanks in advance!

 

Get a tuner. I know an Edge will do what you need.

 

Just about any tuner/flasher will allow you to enter your tire size and gear ratio which properly caibrates your speedo.

 

Mine is always plus... When the speedo says 60 my gps tells me 64/65... So if I wanna do 65 i keep to 60mph...

Is yours the opposite?? I hear ford doesnt re-calibrate for larger tire sizes..

 

I have a superchip with this remote control thing I plug in under the dash...is that the same thing?

Yep mine is the opposite..weird...