The flat or severely under inflated tire is just the extreme. The same physics principles apply no matter how great or little the deformation.

 

Could you run this set up on 87 octane? I have the 4.6 as well on my 04, running level 2 but with no custom settings at all.

 

I wouldn't advance the timing with 87 you can try but if you hear it start knocking then lower the timing back down I read on here one guy claims to be running +3.00 on timing with 87 but rule of them is .50 for each increase in octane for example 89 octane your safe at .50 for 93 your safe at 1.00 advance this is what I was told.

 

How about shift firmness? What exactly does increasing the shift firmness due? Sorry, totally new to all of this!

 

It makes the shifts more snappy in other words it reduces the slippage in between gears and makes it hit harder into gear it's supposed to be better for the transmission

 

I have 255-65R17 tires. I did the calculations and got 2398 or something like that. I plugged that in and the speedo was a couple mph faster than my GPS. I accounted for 3% squish and it has almost made my Edge perfect with the GPS (it's like 0.5 mph off but I don't want to reprogram my truck just for that). I know my truck speedo will never be exact because Ford puts them 2-3 mph faster to save themselves from lawsuits.

 

I've had my Evo for my 04 4.6L for a while and I've tried a lot of tunes: lvl 2 87 with no timing, lvl 2 93 with +3 timing. Lvl 3 93 with +1 timing. Lvl 3 gets me the best hwy mpg (19-20 avg). My mpg seems to have gotten better on the hwy, but worse in the city with the K&N intake. Lvl 2 93 with +3 felt like the best of both worlds with lv 2 torque but the lvl 3 power. Can't remember why I switched. Probably because lvl 2 seems to slow down my truck more when I let off on the hwy (my exhaust pops more like I downshifted)

 

You don't have to re-program the whole truck to change your tire size...just go into where the tire size is and change it...and Ford does not cal there speedo's 2-3 MPH faster...they are dead on...look at your GPS and stock tire's they should match.

 

Which one are you running now? And any lean issues

 

Every Ford I've ever driven, and there have been MANY, other than police service vehicles have had the speedo read 2-3 MPH faster than actual. That includes my current 2005 F150 and 2008 Taurus X.