I put a set of 35's on my 05 and went through the programming procedure on the edge for reprograming tire size. I measured a complete revolution of the tire because the tires were used when I bought them with @ 60% tread. The problem is my speedo is not changing according to my gps. It was reading four mph slower than the gps when I entered the new tire size based on the measurement, so I increased the number by 100mm and still 4 mph slow. I increased the size by another 100mm, still 4mph slow. It is like it is not having any affect on the speedo when I change the tire size in the edge tuner. What do you think, guys? It looks like I should have seen some kind of change, but I haven't. Am I doing something wrong? I called myself following the directions in the manual. Oh, yeah, I spent the better part of an hour searching the forums for an answer, but found nothing related to my problem(could have been typing in the wrong combination of words, its late) Thanks, guys!

 

i can think of only one thing. Are you sure your gear setting is correct?

 

One other thought. You need to syncro the Edge speedo with the GPS. The truck speedo will always be faster, usually 2 or 3 mph.

 

I upped the mm's by another 100 today and still no change. The speedo is still approx. 4.8 mph slower than the gps. Gear size is correct, 3.73, so I don't understand what the problem is. The changing of the tires size is not having any affect whatsoever on the speedo. I haven't tried syncing the edge speedo with the gps. I will have to check the manual to see how that is done. If that works, wouldn't it be more accurate than changing the tire size? I'm just wondering if something is wrong with my tuner.

 

Or maybe the GPS is incorrect... just a thought.

 

the difference has been a consistent 4.5-4.9 mph difference. Something should be changing somewhere! I just read a post about playing with the gear ratios while also changing tire sizes. May give this a try to see if I can get any change in the edge speedo relative to the gps reading. Hey, Bluejay. Wasn't that you who mentioned playing with gear ratios along with tire sizes to get the speedo closer? If so, is the final decision that it will not affect shift points when changing ratios in the tuner only?

 

I have corrected mine and it worked. Are you sure your going all the way through with it? You have to reset the level and it wont adjust on the stock tune setting. You have to select a performance level and set the tire size and it has to reinstall the complete level. It goes back to stock size everytime you change levels as well if you dont set the tire size.

 

When I said snycro the Edge with the GPS, what I mean is, have the Edge display teh speed and adjust the tire size so that the GPS and the Edge read the same. Like said above, it does sound as if you are not going all the way through the process of entering the tire size, hit enter and the select "done" and hit enter, and let it reprogram.

 

Yep, sounds like you're not using the programmer properly. You have to do a completely new flash everytime you adjust the tire size for it to work.

 

After you make the change in your tire size, you ARE hitting the <Enter> key to accept it, aren't you?

And then, when you finish this (and other changes) you are selecting the "Done" menu item, right? And, the unit tells you to turn the key off then back on again and you sit for a while and watch the PCM get programmed?

If you miss any of these steps, the tire size is not being stored in the PCM.

- Jack

 

I was skipping a step in the programming process. I was not scrolling down and selecting "done" when I entered the new tire size. Went out last night after reading the replies and did what yall said and it updated the program with the new tires size. I still have some tweaking to do to get the speedo closer, but you guys are the greatest! Thanks for getting me on the right track!

 

Glad you got it figured out. More often than not, it's something simple like that. Now, if you get the GPS synced with the Edge, then your truck speedo will usually be about 2 mph fast. That is how Ford has them set.

I try to get the Edge accurate and I keep the digital speedo in the upper right corner. It's much easier for me to see than the truck speedo.

 

That happened with me twice, I forgot to select Done and Enter, and when I kept going back to make adjustings to level 3 I was wondering why it kept resetting everything believing it wasn't properly programming but it appeared to.