Help me to change my speedometer

[PontiacFan]

I've read a lot of information on this and it has actually just left me more confused at this point.

I'm only changing the tire diameter, no gearing. The tire diameter is going to increase...going from a 225 60 16 to a 235 65 16. I'll do a rollout test to have the circumference.

Unfortunitely, I can't do the auto scale feature because the buttons are ghosted over, I have to enter these numbers manually.

What number exactly do I need to change? How do I change all the shift points without having the auto scale feature?

[PontiacFan]

I've been thinking this over and I think it makes more sense...Is the pulses per mile the only number I need to change to make the speedomter accurate and the shift tables are only changed due to the fact that the vehicle would be shifting at a different RPM with a different diameter tire? Everything else stays the same, right?

[Ivan]

Multiply 26.6 (actual tire height) by the tire/gear number in the speedometer section, that is your gear ratio. Now divide the new tire height, 28 by the gear ratio. Enter that number in the new gear/tire box, leave it on auto, and press commit.

Good Luck!

Ivan