Edge Evo and new tire size ?'s

[ATNryan]

I am familiar with most of the functions on the EVO, but have to questions about how it is actually functions since I upgraded from stock wheels and tires to aftermarket rims with 35's. 1) When I make adjustments on the Evo for the bigger tires, I know it is adjusting for the speed it reads on the display, however is this also being changed on my stock speedometer gauge? 2) If the above is true, is it also adjusting my odometer for the bigger tire inputs too? I am curious about this because I would like to be able to get some idea of the MPG. Thank you for your help!

[JackandJanet]

Originally Posted by ATNryan

I am familiar with most of the functions on the EVO, but have to questions about how it is actually functions since I upgraded from stock wheels and tires to aftermarket rims with 35's.

1) When I make adjustments on the Evo for the bigger tires, I know it is adjusting for the speed it reads on the display, however is this also being changed on my stock speedometer gauge?

2) If the above is true, is it also adjusting my odometer for the bigger tire inputs too?

I am curious about this because I would like to be able to get some idea of the MPG. Thank you for your help!

YES to both questions. If you get the speed display on the Edge to be dead accurate, the dashboard speedometer will be about 3% fast (2 mph at 70 mph), due to mechanical imperfections, and the odometer will be corrected too (and won't have that error - since it just "counts" axle rotations).

What I just said is true for later MY trucks. Early trucks did not control the speedometer through the PCM, but that changed in the 1999-2000 timeframe I believe.

If you have 35 inch tires, you might start with a Tire Size (TS) of 2709 mm, which includes a 3% reduction for "squish". If you open the Custom Options menu, you MUST verify that both the TS and Gear Ratio (GR) are correct. The Edge can load bogus, placeholder values into these positions as soon as you open that menu.

- Jack