Can I use Forscan to adjust for tire diameter? If so I need a VERY detailed walk through. I have never used it before and I am just finding out about it.

 

You can only adjust it to a factory ford size at least the last time I tried. Maybe someone else can chime in and correct me.

 

It doesn't seem to actually adjust anything. Like Forscan is missing something that IDS has. We've discussed it quite a bit in the Forscan thread, and elsewhere. Although, new versions of Forscan come out every so often, not sure if we've really tried the latest with this question.

 

I haven't poked around in Forscan much lately, but I don't think it has the ability to program the PCM (like a tuner does). And it seems to me like the PCM adjustment is what is needed to correct the speedometer. As mentioned, several guys on here have tried to adjust the speedometer with Forscan and reported no change. I adjusted my speedometer with my SCT X4. It worked, but Forscan still lists the stock tire size.

 

People with 2011-2013's have had little success with adjusting the tire size for speedo accuracy. I have a 2014 and it worked for me until I bought my tuner.

 

Even though the factory ford sizes are listed as changeable, changing them does nothing in my experience. If you do change it, there will be an error in the PCM (i think), and not throw any codes on the dash, its more or less a "tire size mismatch".

Pretty sure 15+ you can change tire size with forscan though.....not sure.

 

Not to hijack the thread but what would be the best tuner to use for a simple tire size change? I switched from 265/60-R18 to 275/55-R20 tires on my 2013 SC. It's at least a 2 mph difference on my speedo and, of course, everything else is off as well, including the odometer and mpg calculations. I've been staying away from a tuner until my extended warranty is expired. Thanks!

 

 

Thank you Nerdh3rd!

 

Might want to check the price on that. Lots of people just opt for the tuner if that's on their list, anyway.