Okay, I'm confused and need some input. I have an 4.6L 05 Screw. The truck has 305/55/20 Terra Grapplers (33") and I have the Edge installed and programmed to their listed size of 2632mm. When on the highway speedo reads 80-85 and from the flow of traffic and feel there is no way I'm doing 80-85. Unless I'm missing something,wouldn't larger tires equal slower speedo reading than I'm actually going.

Question is, do I need to change the programmed gear setting in the edge to get additional speedo correction or is that setting only changed when you physically change the gears? I'm wondering this because the effective gear ration has changed with installing the larger tires.

Thank in advance for you input... JB

 

If your tire calculation is right then the only thing i can think would be wrong is that your edge doesn't have the correct gear ratio in the program. My edge tells me the stock gears in my truck is a 3.31 but its really a 3.55 so i would check to see if the edge has the correct ratio programmed in it.

 

Above post is correct. The unit comes preprogrammed with a gear. Make sure it is what you really have, if not, change the gear setting. I ahve to on mine every time.

 

Thanks for the replies... I'll check that out today.. It reads that I have 3.73 gears and I'm 99% sure I do. At least that's what it says on the dealer window sticker. I'll check the manufacture codes when I get home today. To save me from doing a search here does anyone have information on where to locate the codes and what it should be for 3.73 gears (LS and non LS)?

 

TXallstar is right. I had the same problem with my Edge and posted on previous thread titled "Edge reveals truth". Check it out.

Also, you can check for proper installed gear ratio by looking at the Certification Label mounted at the bottom of your trucks B pillar. It will list what axle you have.

19 = 3.55 open
H9 = 3.55 LSD
26 = 3.73 open
B6 = 3.73 LSD
27 = 3.31 open
18 = 3.08 open
25 = 4.10 open
B5 = 4.10 LSD

Don't rely on the the circumference numbers that Edge gives for tire size as they can be way off. Measure circumference with the tire inflated correctly and at least a half tank of gas to take in account the "squish" factor. Edge printed in their manual that 285 70R/17's would be 2689mm when mine are actually 2515mm circumference.

 

I verified I have a 3.73 open by looking at the lable on the door.. That's what is showing on the Edge gear setting (so that is correct). With my 305/55/20's on from my calculations the tire size setting should be 2649.2 (I loaded 2650). The lower speeds it seems that the speedo & edge reading are right on but when I'm on the highway (70-85mph) range is where things get screwy. When the speedo & edge read 80-85 it feals as thought I'm doing 70-75mph. I can also judge by the flow of traffic that I'm not going as fast as it shows.

I think what I need do is have someone pace me at the questioned speed and see what I get. I know it won't be 100% accurate but it will give me a better idea. It may just be the new feel of the larger tires that have me scratching my head.

Has anyone every seen anything like this before?

 

I felt mine was off, so plugged a friends Tom-Tom in and it said I was fast by 2 mph. So it was just me. If possible, get a portable GPS and check it out.

 

I'll do that.. It's probably just in my mind.. Bluejay, I sent you an email.. What type of fogs do you have installed?

 

When i do the calculations in the edge manual for tire size it comes out to 1485? which i know aint right. An online tire calculator says the tires are 2682mm, but when i put that in the speedo is still off. The speedo is over by about 2-3 mph. When the edge says 70 the speedo is reading more like 72-74?? anyone know of anything that could help me out? I may just have to do the deal where you time between each mile marker. .

 

How did you do in algebra? Seriously, there has to be something wrong with your math or there is a misprint in your manual. When I did my calculation, it came up with what they had listed.