FlashPaq Speedo Cal - 285/65/20
08-12-2017, 10:10 AM
#1
Member
Thread Starter
FlashPaq Speedo Cal - 285/65/20
What tire diameter did everyone put when calibrating their speedo? Just curious...
I set my speedo with a FlashPaq from Superchips yesterday and I have 285/65/20 KO2's. The overall diameter of that tire state 34.59" however so I set the cal to 34.50" - speedo was way above the speed, said it was doing 70, actually 65. I got out and measured the tire height from the ground and it was 33.37" @ 40 PSI so I re-calibrated for 33.25" on the FlashPaq and now it's ok with about a .5mph difference from the GPS.
The factory setting on the truck was for 29.50" and I know the stock tire size is 31.90", so 2.4" off from tire spec. I didn't have time to try the math and set it to around 32.25" so I might try that today while I have some time.
I know you can do this with ForScan, but I wanted the FlashPaq incase I decide to do a tune later all I have to do is flash the unit and pay the upgrade fee.
I set my speedo with a FlashPaq from Superchips yesterday and I have 285/65/20 KO2's. The overall diameter of that tire state 34.59" however so I set the cal to 34.50" - speedo was way above the speed, said it was doing 70, actually 65. I got out and measured the tire height from the ground and it was 33.37" @ 40 PSI so I re-calibrated for 33.25" on the FlashPaq and now it's ok with about a .5mph difference from the GPS.
The factory setting on the truck was for 29.50" and I know the stock tire size is 31.90", so 2.4" off from tire spec. I didn't have time to try the math and set it to around 32.25" so I might try that today while I have some time.
I know you can do this with ForScan, but I wanted the FlashPaq incase I decide to do a tune later all I have to do is flash the unit and pay the upgrade fee.
08-12-2017, 10:49 AM
#2
Senior Member
I think most guys on hear had to do the same thing weather they used the superchips or the hypertech unit.
08-12-2017, 01:14 PM
#3
Senior Member
I have the same tires as you, and I calibrated with my SCT X4, mine was way off from what it "should" have been as well. You'll unfortunately have to just keep adjusting it till it gets close. Kind of a trial and error type deal which sucks because the whole process takes so long, but you'll get it.
08-12-2017, 04:02 PM
#4
Senior Member
Two different diameters. Loaded and unloaded. Air pressure makes a difference as well. You can fine tune the speedometer by slight adjustment of the air pressure.
I'm surprised that the calibration units do not mention that in the instructions.
I'm surprised that the calibration units do not mention that in the instructions.
08-12-2017, 04:14 PM
#5
Senior Member
What tire diameter did everyone put when calibrating their speedo? Just curious...
I set my speedo with a FlashPaq from Superchips yesterday and I have 285/65/20 KO2's. The overall diameter of that tire state 34.59" however so I set the cal to 34.50" - speedo was way above the speed, said it was doing 70, actually 65. I got out and measured the tire height from the ground and it was 33.37" @ 40 PSI so I re-calibrated for 33.25" on the FlashPaq and now it's ok with about a .5mph difference from the GPS.
The factory setting on the truck was for 29.50" and I know the stock tire size is 31.90", so 2.4" off from tire spec. I didn't have time to try the math and set it to around 32.25" so I might try that today while I have some time.
I know you can do this with ForScan, but I wanted the FlashPaq incase I decide to do a tune later all I have to do is flash the unit and pay the upgrade fee.
I set my speedo with a FlashPaq from Superchips yesterday and I have 285/65/20 KO2's. The overall diameter of that tire state 34.59" however so I set the cal to 34.50" - speedo was way above the speed, said it was doing 70, actually 65. I got out and measured the tire height from the ground and it was 33.37" @ 40 PSI so I re-calibrated for 33.25" on the FlashPaq and now it's ok with about a .5mph difference from the GPS.
The factory setting on the truck was for 29.50" and I know the stock tire size is 31.90", so 2.4" off from tire spec. I didn't have time to try the math and set it to around 32.25" so I might try that today while I have some time.
I know you can do this with ForScan, but I wanted the FlashPaq incase I decide to do a tune later all I have to do is flash the unit and pay the upgrade fee.
Tire Height
Corrects the speedometer and odometer for
vehicles with aftermarket wheels and tires. In
vehicles with automatic transmissions it corrects the
shift points.
Measure from the ground to the top of your tire.
Place a ruler or flat level item on the top of your
tire to measure accurately. Measure in ¼ inch
increments & round up.