Alright guys i just down sized to 305/60-18 Tires from 325/50-22. I cant get my Edge to recalculate the correct speed. I did the math and it came out to 2356mm. The speed is still showing 5mps +/- off. Any ideas?

 

the edge should have a metric and standard size, Is yours an older edge? Pre 2009?

 

Ya it only lets you enter it in mm. I never had a problem with it being inacurate with the 35s but now I cant get it dialed in for 33s no matter how many times i check the math formula conversion. Looking to see if anyone else is running this size

 

I had the same problem, using the formula the MPH was off. I then measured a tire rotation on my driveway and entered that in and the MPH was spot on.

 

^^^^^^^^^

or if you don't want to do that.

Take 2356 X .03 or .04 for a "squish" factor...... the 2356 is pretty accurate when the tire is sitting on a bench, but under the weight of the truck is not accurate....

 

Are you using your gps to check your speed????


If so, just keep adjusting it till you match your gps

 

2682 took me awhile to do mine, I downloaded an app on my iphone to measure the speed. My GPS is also the same.

 

Sorry just noticed you had 60's not 65's.

 

the squish factor worked times what i got by .03 and now speedo is within 1mph.