Gryphon won't correct tire size

[Jackpine]

Colby, that's a clever use of the odometer to correct things.

For anyone that doesn't understand why, it's because the odometer doesn't depend on speed. You can drive that distance at varying speeds and it won't matter. The same error that's present in the odometer is also present in the speedometer, so by correcting the TS by that amount, you correct both odometer and the speedometer.

- Jack

[btownford]

Thanks guys...i swear i did the same procedure earlier but it did work. I adjusted the tire size wo the 6% squish (great explanation btw) and i'm about 3mph off. I haven't had time to fine tune it but thats acceptable by me.

Thanks for the help guys!

[ROB281]

noticed that mine is off as well

my gps says the distance between my office & apartment is 24.9 miles

odometer says 28

my speedo is also reading slower than the gps as well

[Longshot270]

Originally Posted by ROB281

noticed that mine is off as well

my gps says the distance between my office & apartment is 24.9 miles

odometer says 28

my speedo is also reading slower than the gps as well

So then to correct it all you have to do is multiply your current tire size by 1.1245 (28/24.9)
Also, write down the new tire size on a piece of paper. That way, if you have to adjust the tire size more you can multiply the odometer/gps fraction by the number you wrote down.

Its also a good policy to write every change you make with the gryphon down onto a piece of paper and save that paper for future reference. I keep my paper in the pod behind the gryphon after I fold it so that it wont be able to slide out of any cracks...I resort to the good old fashion paper ball fold.

[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.