SCT X4 and tire diameter
11-23-2015, 09:23 PM
#1
Senior Member
Thread Starter
SCT X4 and tire diameter
I switched to Snow tires which are 30.1 in diameter vs the 20's which are 31.9. Revs per mile are 671.5 vs 632.4. The SCT has revs per mile in increments of 5 MPH.
According to the tire calculator the speed difference is about 4 MPH @ 60 MPH. So far I reprogrammed 3 times, starting at 670, to 675 and now at 680 and my speed is still too low, which is about 3 MPH difference. I compare the speedometer to my Garmin GPS.
The SCT has the 5* tunes in it, are the options available but locked when loaded? I really haven't seen much difference between the 3 reprograms.
According to the tire calculator the speed difference is about 4 MPH @ 60 MPH. So far I reprogrammed 3 times, starting at 670, to 675 and now at 680 and my speed is still too low, which is about 3 MPH difference. I compare the speedometer to my Garmin GPS.
The SCT has the 5* tunes in it, are the options available but locked when loaded? I really haven't seen much difference between the 3 reprograms.
12-01-2015, 04:44 PM
#2
Return the truck to stock tune, then go in and change tire size. Make sure it's where you want it via gps then go back to the custom or canned tune and when asked select the leave it stock if it prompts for tire size.
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