Speedometer Gear Change??

[97expy]

I have a 1997 Expy that came stock with 255/70r16 and I put on the 265/70r17. Now the speedometer is way off. The Expy has the 4.6L Auto 4x4, I do not know the gear ratio as I do not have a owners manual.
Has anyone done this upgrade?? Does anyone know the VSS gear I need to correct the speedo?
Before anyone posts that other link again, my Expy is gear driven NOT electronic speedo, and I don't have a digital readout on my gauge pod.
Thanks for any help!!

 

[pronstar]

Man, it's been so long...I bought my VSS gear from Steeda. The Mustang VSS gears work for our trucks.

IIRC:
1. figure out how many teeth are on the VSS gear you have now

2. calculate the percentage change in rolling circumference between old tires and the new ones

3. Order the VSS that will give the appropriate change (likely a 1-tooth change)

I think if you call them, they can help you out.
http://www.steeda.com/