Rim Dia. Calculation 17 * 25.4 = 431.8mm
Tire Sectional Dia.. Calculation 265 * .70 = 185.5 * 2 = 371

Total Dia. 431.8 + 371 = 802.8mm

Circumference 802.8 * Pi 2522.07mm Round to 2522

Rolling circumference will be about 97% of the Hanging Circumference of a properly inflated tire, so 2522 * .97 = 2446.34 so 2446mm
I have been using this since before I found the video. He calculates in Inches, but Just apply the Ratio to the Millimeters for your Rolling Circumference.

My calculated is 2646(275-70/18) but my edge reads dead on to mt GPS at 2604, and my Custom tune for my size came from Power hungary at 2567(which is 97%) but I air my tires high 65-70 PSI since they are 80psi Tires.

 

The numbers on this screen represent the circumference (in mm) of your tire
size. The default value the Evolution displays is the current value stored in
the PCM. Adjust the tire size by pressing the [UP] and [DOWN] arrow keys.
The following table will help you determine your tire circumference by
matching your tire size with the common sizes listed. For example, if your
tire size is 285/ 65-18, the value (circumference) you enter into the Evolution
is 2600. You may also use the formula provided to determine your
approximate tire circumference. Finally, you may also measure your tire’s
circumference by marking your tire and rolling it one complete revolution
and measuring the distance in inches or millimeters. If you measure in
inches, multiply the distance by 25.4 to convert to mm. (ex. 91.3 inches x
25.4 = 2319 mm). The range of change is from 2000mm to 3500mm in
increments of 1mm.
Width Ratio Rim Circumference Tire Size
265 70 16 2441mm 33 2632mm
275 70 16 2485mm 35 2792mm
305 70 16 2617mm 37 2951mm
215 75 16 2289mm 38 3031mm
245 75 16 2430mm
265 75 16 2524mm Circumference Equation:
285 75 16 2618mm [(width * ratio * 0.02) + (rim * 25.4)] * 3.1415
295 75 16 2666mm Steps:
305 75 16 2713mm 1. Multiply Width, Ratio and 0.02
315 75 16 2760mm 2. Multiply Rim and 25.4
325 75 16 2807mm 3. Add Step #1 with Step #2
265 70 17 2521mm 4. Multiply Step #3 with 3.1416
285 75 17 2698mm 5. The result will be the circumference of your tire in mm.
315 75 17 2840mm
275 65 18 2559mm
285 65 18 2600mm
285 60 18 2510mm
325 60 18 2660mm
Caution: When adjusting the following values, it is highly advised to make
gradual changes as opposed to aggressive changes. This will help avoid
possible powertrain damage.
Idle Speed
This adjustment modifies the base Idle Speed of the engine. Select the RPM
you would like to add to the base idle speed. For example, if the normal base
idle is 600 RPM and you want 725 RPM, set the option value to 125 RPM.
(600 + 125 = 725) This option will only raise the base idle, not lower it.
WARNING Idle speeds above 800 RPM may cause vehicles with
automatic transmissions to "creep" when stopped while in gear, requiring
additional pressure on the brake pedal in order to keep the vehicle
stationary.

 

that is right from the book

 

I got my truck not long ago and it came with a Evo tuner already installed. The entire time I've had it, it hasn't worked. Whenever you plug it in it'll come on and give the warnings then the truck file and freeze at that. Any of y'all ever see this?

 

Does it say hex file not located or anything? It might be fried.

 

Says hex file then gives a long number. That's where it's frozen.

 

Try and update it via Edges website, its free.

 

So i heard from a forum that you can inrease timing +1 for every 2500' above sea level.. My timing on my truck is 1.5 on 87 tow with 91 octane and i live around 6500 ft. Should i go to 3.5? lol i really think this +1 for feet thing is bull shlokin. Also my 0-60 here is and im sure its cause of elevation and my 35 inch oversized tires and maybe the 6'' fabtech lift. but im getting 10.5 seconds. once again i live around 6000-7000 ft. Any ideas.

 

Just got the Edge in the mail.. have to say, so far I've noticed a difference just adjusting my tire size because of my bigger tires and lift. I feel like I'm back in my stock f150!


Ok so the book says to run 87+ for a level 2.. am I okay to use only 87 then? I'm reading a lot of you are running 89 for your tow. I am just curious, not arguing at all. I'm new with a tuner. Is it just preference or have you just seen a difference going with the higher octane?

 

87 Octane is right for the level 2 unless you run level 2 and do a custom setting on it and increase your timing, then you will have to run 89 (if doing a +.25 on timing) or you can run 91 octane with a level 2 timing bump of +.50. These are "safe" numbers. Of course, if you ever hear pinging or rolling marbles sounds from your engine after a timing adjust, back it down a notch.