My stock pcm says it is set fot a stock 245 50 16 tire as 24.95xx inches (even thought I have 315s on there now). The calculator in HP Tuners says stock tire height is 25.6".
Now, my 315 35 17 tires in the HP Tuners calculator comes to 25.7" which is only .1" difference. Do I plug in 25.7" for the new speedometer calibration, or the stock pcm reading (24.95" plus the .1" difference (25.05"??
Thanks.