There is this thread but I didn’t dig that deep into the posts on this. I think with Forscan it’s a little tricky. If you do throw a code from doing it wrong it’s difficult to reset. In this case it does sound like a tuner module is the better alternative for doing this.
It all was to me too. I never knew I needed to replace perfectly good tires until I joined this site.
There's even an old post I made where I swore I didn't need a tune and guess what, that lasted about 6 months and I got a tune. 
If you do decide to get a tune it's really easy to adjust the tire size from the calibrator.
Are you happy with your tune? I’ve been thinking about it.It all was to me too. I never knew I needed to replace perfectly good tires until I joined this site.
100% and wish I did it sooner. I went with the Livernois tune and you get 5 tunes so you can try them all and see which one you like. Another really good one is Unleashed and then there's the Ford Performance tune which many like because you retain the factory warranty.
I was always curious how these local dealers with upfit packages of bigger wheels and tires adjusted the speedometer accordingly. My guess is they probably don't even bother which is concerning…So I’ve been looking at getting bigger tires and would like to have my speedometer calibrated after. Unfortunately my local dealership said they don’t do that. How did you guys go about it if you did? I’ve heard that you can do it with ForScan but I honestly don’t know anything about that. ??
