jc5057

I have a question as I have a 2015 GT Premium that came with 20 inch wheels stock.

The issue is I have 20 inch rims on the back but I went with M/T 305/35/20 that increased the sidewall height so now I am a mile faster then speed shows


So my PCM was calibrated by Roush for the supercharger and roush told me they needed the car to set REV per MILE which is now 717


So will a dealership do this or do I have to buy a handheld tuner to do this?

I have discovered with the supercharger and taller wheels on the back the car is bouncing off rev limiter as this has changed my RPM tack as well

So any advice or how to is greatly appreciated

jwog666

the rev limiter has nothing to do with tire size, the revs per mile is only used to calibrate the speedometer . you are hitting the rev limiter because your engine is revving that high. if you want to adjust a dealer wont touch that for you, they dont have the ability with the ford tool. you will have to have roush do it, as it is already tuned.