nelmsinhd

Sorry if this is the wrong section...

Vehicle Stats:
Year: 2007
Model: F150 FX4
Drive: 4x4
Tires: 37''
Suspension lift: 5''
Body Lift: 3''
Tank: 25g

Currently pulling ~260 mpt, 150 mpt to the half tank mark. (combined)
~ 10mpg

Question:
First off - Obviously my vehicles Speedometer is showing an incorrect reading due to the tire size. My question is, does this make and model have the speedometer and odometer run together? Not really sure how to explain it... If i go "70" mph (when i'm actually going like 80) will my odometer read that I traveled 70 miles instead of 80??

Spanky666

Speedometer is controlled by electronics, but the tripometer and odometer are both controlled by a little plastic worm-gear that is notorious for slipping in Fords. Can be replaced though.

nelmsinhd

Yeah, the odometer worm. I'm trying to figure out if the speedometer and odometer work together. If the speedometer is off by 15MPH, will the odometer also be off?

Spanky666

I'm gonna say yes, because the ratio is off due to your tires. The gear ratio is designed for the factory tires.

But as far as the speedo and the odometer, they are still separate in the sense that, the odo and trip are driven by a gear, and the speedo is electronic. (Not sure if the gear is driven electronically or not, never really paid that much attention to it). Nonetheless, the gears are designed at a 1 to 1 ratio given the factory tire size, and if you alter the ratio, it will alter the reading.

I've never done it, but I'm sure there's a way to reprogram the computer for a change in tire size.