So I just had 4.56 gears installed in my F150 FX4 and my speedometer is all jacked up about 15 mph off at 60.

 

what size tires are you running?

 

You'd need a programmer to fix your speedo for you. That's pretty much all there is to it. The programmer gives you an option to input what gears you have and it changes the speedometer according to that.

 

my bullydog didn't have the gear input but had the tire size input for the speedo change.. I thought our trucks have sensors and not wire? if it is sensor then the gear ratio shouldn't change the speedo correct? If he changed out his gears and put bigger tires on I can see the speedo being off.

 

So I've had 33" Procomp MT2s on now for a few months, but I didn't see any change in the speedometer, but today I got my truck back after the gears where changed and I see a huge difference.

With the Edge Evolution allow me to input gears and tire size? I also have exhaust so even without a custom tune I assume the stock ones will still help? Or is there a better tuner for this?

 

The Edge Evo will do just that for you. There are all kinds of custom options and two of them are changing your tire size and changing the gear ratio.

 

That is weird I don't see how just changing your gears is going to throw off your speedo that much. do you have any abs lights since you had your gears installed?

 

No lights, just got the truck back a few hours ago, and was like damn it doesn't feel like I am doing 70 in traffic hour lol.

 

maybe I am just turned around from the old school trucks with the wire driven speedo and these sensor driven speedo's.

 

The gears are awesome aren't they? I have them in my FX4 and paired with the shift kit, the truck barks the tires really hard on the 1-2 shift.... Even with 35's.
Typicaly when it comes to gear and tire height is that .1 change in gear = 1 inch in tire height....... So if you had 3.73's before thats a change of .83.... Or 8 inches taller tire so a 41 inch tall tire..... Hope that helps.