'06 F150 Screw w/5.4

Just got my edge uploaded to level 2 and corrected my tire size. Now, on a flat straight away, have the truck speedometer at 80 with the cruise control. Edge says that I am going 77. Handheld GPS says that I am going 74. I dont know which to go by. Its getting very aggravating.

Thanks in advance for ady light on the subject.

 

There have been alot of debate on this subject. I will give you my take on the situation. First measure your tires to make sure you have the correct size(you may have done this). Also as your speed increases the diameter of the tire changes. Air heats up and expands. Rotational forces on tire ect.ect....

Also the speedo is mechanical and some have said that it can have up to 3% error in it. I would use the gps and change the tire size till you get as close to the mph that you want it to read.

Also try search for much more info.

 

I would say your GPS is correct.

Did you use the rolling method of getting your tire size?

I found a pretty good difference in the recommended size in the EDGE manual,and my true numbers.

Also, all of these trucks have a 2-3 mph error from the factory. i.e. you show 80, and the true speed is 77.

I remember the EDGE people explaining it on another post.

So double check your numbers on the tires size, and you should get pretty close.

 

GPS, unless you bought it from bubba at the dollar store / pawn, will be right 99% of the time

the edge manual just gives you some approximate numbers. youll still have to correct it via GPS (its good you have one). everyother programmer; diablo, superchips, 9100, babyjesus buddah troyer's SCT (how dare i compare it to average products), van aken, and all of them will be a small bit off because of tolerances in the programming and peoples tires. its always safer to check with a GPS; its safer for you, other motorists, and your driving record

 

ok, so if i am understanding correctly, i need to adjust my tire size on the edge until I become fairly close to the speed the GPS states.

Does anyone know if that means making the tire size bigger or smaller off hand.

 

You want it to register slower, so bigger.