Gryphon won't correct tire size

[gilsnuxs]

OK, Ive tried the formula using the odometer and my speedo is still off by the same amount. GPS reads 67, CTS Unit reads 70, and Truck speedo reads 73. Stumped. If it helps, I have Nitto 325/60/18 so I used 2660. Truck odometer was 10.7, GPS was 10.3. I got 1.0388 x 2660=2763 2763-3% for squish=2680. THats what I used.

[shotgun]

Originally Posted by gilsnuxs

OK, Ive tried the formula using the odometer and my speedo is still off by the same amount. GPS reads 67, CTS Unit reads 70, and Truck speedo reads 73. Stumped. If it helps, I have Nitto 325/60/18 so I used 2660. Truck odometer was 10.7, GPS was 10.3. I got 1.0388 x 2660=2763 2763-3% for squish=2680. THats what I used.

Unloaded circumference is 2662mm. Allowing a 3% squish factor = 2662 x .97 = 2582mm

Double check:

10.3/10.7 = .96

2582/2680 = .96

Also make sure that you are properly saving the custom settings.

http://forum.gopowerhungry.com/faqs-...ions-menu.html

[Jackpine]

Originally Posted by gilsnuxs

OK, Ive tried the formula using the odometer and my speedo is still off by the same amount. GPS reads 67, CTS Unit reads 70, and Truck speedo reads 73. Stumped. If it helps, I have Nitto 325/60/18 so I used 2660. Truck odometer was 10.7, GPS was 10.3. I got 1.0388 x 2660=2763 2763-3% for squish=2680. THats what I used.

Looks to me like you've INCREASED your TS for "squish", which would make your CTS read "too fast", A 3% squish on your tires reduces the circumference to 2581. That may be too small, looking at your numbers, but the correct TS should be somewhere between 2660 and 2581.

Edit: You're too fast for me Shotgun! And you were absolutely right.

- Jack

[Longshot270]

Originally Posted by gilsnuxs

OK, Ive tried the formula using the odometer and my speedo is still off by the same amount. GPS reads 67, CTS Unit reads 70, and Truck speedo reads 73. Stumped. If it helps, I have Nitto 325/60/18 so I used 2660. Truck odometer was 10.7, GPS was 10.3. I got 1.0388 x 2660=2763 2763-3% for squish=2680. THats what I used.

Ok, dont worry about squish when you use this formula. The tires size in the programmer should already compensate for that.
I'm not at my computer right now but I think when I put in my tire size and play with the amount of squish it comes out to 4.5 or something like that for 235/70-17 tires on an 8.5 inch rim. Try using the 2763. This method isn't always a one shot deal sometimes. Things like GPS errors and incorrect tire size values can throw it off.

Haha and I didn't see you other guys post.