GM SPEEDO calibration questions, much like everyone else but i got different question

[jchidley]

so i know where to go to mess around with my VSS signal and i know that my 315x30/18 wheels are 79.9 around and 749 rev per mile. i know that my rear end is 3.70:1. so how do i come with the trans rev per mile? also

Standard V8 Rear Wheel Drive Applications (1999 to Current)

Insert your new tire and gear in the columns on the right. If your tire height has not changed, enter the same value. If your gear has not changed enter the same gear value.
When you have entered the correct values for your vehicle click the "Calculate for New Values" button. This will use the values you entered to determine the new VSS Pulses/Mile, Trans Revs/Mile, Final Drive ratio, Tire revs/dist values found below.
When you are satisfied with your changes, click the Save Changes button on the top right of the form.


WHERE IS THIS CALCULATE NEW VALUE Button?

what should my #s be.

LS3 6l80E 6 speed trans
tires 749 rev per mile
3.70 rear end gears.

[5FDP]

If you use the gear/tire wizard under the edit tab and have it auto scale the transmission and speedo settings it will do it for you.

[jchidley]

you sir are genius. thank you. for autometer do i keep it 40.00 on the VSS hardware? and then if it still reads a little off compared to a gps signal. which parameter do i mess with and fine tune to bring it in closer?

[mymonte666]

Change the vss output small numbers faster larger numbers slower.

I'm goin to jump on this while i'm at it.
Why would my traction control activate after changing the tire size to correct the speedo? This is an 01 tahoe and went from fctory 16's to 24's. The truck is not driveable unless the traction off button is pressed.

[tek1229]

Change the vss output small numbers faster larger numbers slower.

I'm goin to jump on this while i'm at it.
Why would my traction control activate after changing the tire size to correct the speedo? This is an 01 tahoe and went from fctory 16's to 24's. The truck is not driveable unless the traction off button is pressed.

01 you should be able to go into the EBCM and recalibrate it for different tire sizes with a tech2 or GM MDI and tech2win.. Hopefully you can find a tire size close to what you put on.. You can use a tire size calculator to compare circumferences from what you have to the choices your given..