First Time Forscan User; Tire Circumference Recommendation

[CLopey]

Hey all,

Just fiddled around with Forscan for the first time. I mainly did it to calibrate my speedometer/odometer to my new tire size. I have 265/70/17 BFG Trail Terrains which are supposedly 31.6”. Gemini AI suggested I change my tire circumference to 2463mm. Is this right?? I now notice that my MPH are about 2-3 OVER what the Google Maps GPS is reading. Google says this is how the trucks normally come from the factory. Help please!

While you’re here, any other mods I should consider?

I did Bambi mode, disabled auto start/stop, changed the battery state of charge to 90%, and changed the Sync screen to the Ford Performance with the cobra (pretty cool!)
I tried doing global windows to roll the windows down with the key fob (didn’t work) and I tried to change the blinkers to blink 5x instead of 3 for a lane change (didn’t work).

Thanks as always!

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[TruckBox]

https://forum.forscan.org/viewtopic.php?t=15994

https://www.ranger5g.com/forum/threads/forscan-to-set-tire-size-size-out-of-range.29045/#post-668089

Go measure your tire diameter, plug it into a circumference calc, and then convert that to mm. Then use GPS to double check. None of the tires ive taken a tape measure to equal their rated diameter.

 

[tm1506]

Hey all,

Just fiddled around with Forscan for the first time. I mainly did it to calibrate my speedometer/odometer to my new tire size. I have 265/70/17 BFG Trail Terrains which are supposedly 31.6”. Gemini AI suggested I change my tire circumference to 2463mm. Is this right?? I now notice that my MPH are about 2-3 OVER what the Google Maps GPS is reading. Google says this is how the trucks normally come from the factory. Help please!

While you’re here, any other mods I should consider?

I did Bambi mode, disabled auto start/stop, changed the battery state of charge to 90%, and changed the Sync screen to the Ford Performance with the cobra (pretty cool!)
I tried doing global windows to roll the windows down with the key fob (didn’t work) and I tried to change the blinkers to blink 5x instead of 3 for a lane change (didn’t work).

Thanks as always!

For reference I have my Cooper Road & Trail 265/70/17 set in Forscan at 2398 and this makes my speedometer accurate in Google Maps and Waze. The original setting was 2360.

 

[Colo_Ranger]

I’ve always had to fiddle with the mm number to get it right. There’s “measurement” and then there’s “real world”. No tire brand is exact on their tire size.

 

[Mighty Little Blue]

Turn on cornering mode. It turns on the fog lights with use of turn signal or when steering wheel is turned at lower speeds.

 

[airline tech]

i don't remember them coming on with turn signal (cornering mode) - but yes if below I think 20-MPH they will come on (with a certain degree of steering input) - I have mine enabled - its somewhat annoying but at the same time adds some light on a dark corner turn. (I am on the fence - if I actually like it) - I think the Fogs On with Turn Signals - is a separate setting, I would have to refresh - on this one

 

[Mighty Little Blue]

I might be mistaken on the turn signal, or maybe it was a 2nd setting. Not with my truck now so just going from memory. Now that you brought it up not 100% sure on signal turning them on. I still like the feature either way.

 

[dozxab]

Two things. All speedometers read a little fast due to the fact that car makers have been sued by speeders if it reads slow. I use mile markers along the side of the road until the odometer is right on. I do a 10 mile stretch but do what works for you. I went from 2360 to 2438 for my Continentals in 265/70R17 to read right. Given that they run a bit taller than BFG, drop down to 2425 or so and see what that does.

 

[PltFX4]

Just hoping this is helpful... originally from some post here on Ranger5G Forum...

 

[dozxab]

It does

Just hoping this is helpful... originally from some post here on Ranger5G Forum...

It does vary by brand but a good start.

 

[seanellaz]

Hey all,

Just fiddled around with Forscan for the first time. I mainly did it to calibrate my speedometer/odometer to my new tire size. I have 265/70/17 BFG Trail Terrains which are supposedly 31.6”. Gemini AI suggested I change my tire circumference to 2463mm. Is this right?? I now notice that my MPH are about 2-3 OVER what the Google Maps GPS is reading. Google says this is how the trucks normally come from the factory. Help please!

While you’re here, any other mods I should consider?

I did Bambi mode, disabled auto start/stop, changed the battery state of charge to 90%, and changed the Sync screen to the Ford Performance with the cobra (pretty cool!)
I tried doing global windows to roll the windows down with the key fob (didn’t work) and I tried to change the blinkers to blink 5x instead of 3 for a lane change (didn’t work).

Thanks as always!

If you are looking for the circumference of circle with 31.6” diameter ...
Circumference = 2 x Pie x Radius.
Radius of a 31.6 " circle = 1/2 the diameter = 15.8"
C=2πr. 2 x Pie (approximately 3.14159) x 15.8" = about 99.3" or 2521.5 mm

 

[dozxab]

If you are looking for the circumference of circle with 31.6” diameter ...
Circumference = 2 x Pie x Radius.
Radius of a 31.6 " circle = 1/2 the diameter = 15.8"
C=2πr. 2 x Pie (approximately 3.14159) x 15.8" = about 99.3" or 2521.5 mm

Unfortunately, actual dimension varies a lot by manufacturer but that gives a really good starting point and a formula to work with. I cheated and Googled it.

 

[seanellaz]

Unfortunately, actual dimension varies a lot by manufacturer but that give a really good starting point and a formula to work with. I cheated and Googled it.

Where would we be without Google? I entered the # 2794mm to Forscan for my 35's and the speedo reads pretty accurate. I was too lazy to jack up the truck and measure tha actual diameter of the mounted tires.

 

[dozxab]

Where would we be without Google? I entered the # 2794mm to Forscan for my 35's and the speedo reads pretty accurate. I was too lazy to jack up the truck and measure tha actual diameter of the mounted tires.

I took Google's number and changed it, then drove 10 miles to see how close the odometer was. Brought the laptop and made an adjustment and headed back. It is really, really close now. The factories set the speedometer a bit fast as they have been sued for having it read slow. Traffic tickets and lawyers and all.

 

[DukeCanBuildit]

Where would we be without Google? I entered the # 2794mm to Forscan for my 35's and the speedo reads pretty accurate. I was too lazy to jack up the truck and measure tha actual diameter of the mounted tires.

Reminds of the southern dad whose boy came home from school and the father asked how his day was and what did he learn in school. His son told him he learned Algebra. The father said Algebra, huh? Say sumthin’ to me in Algebra.

The boy replied “Pi r Squared”

The father said that wasn’t right at all and that everyone knows pie are round; cornbread are squared.

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