pro cal error

I just swtiched to 35's actual 315 70 17 which measure 34.69 say 34.75 for pro cal use. when I program the the new tire size in my speedometer is still 9 miles per off at 60 mph. so when my speedometer reads 60 I am actually doing 69. I have checked this 3 ways 2 with gps speedometers on my i phone and also outhouse signs with radar that always tell me to slow down. I can't figure out what to do. should I reset the speedo with a larger tire size that would match the 9 mph error. or is there something else I am missing .

Double check, pro cal setting. I had issues till I noticed I was using the wrong setting. I used the setting for the tire size above the one I really wanted. It's easy to mistakenly do.

I had the same issue w my procal. I just adjust the tire size until my speedo was correct. If I remember right my procal is set to 31.75 and I am running a 315/70/17