quick question about drive teeth/speedo cable

[ozone]

Trying to figure out which speedometer gear I need. Using the info I have gathered, my truck (1993 Ford Ranger 4x4 4.0) has a 3.27 non limeted slip (got this from the door code/Ford service dept) My current speedo gear is a 17 tooth white gear. I am using the gear calculator pointed out by you guys here
http://www.1010tires.com/TireSizeCalculator.asp?action=submit
the number I am missing is the number of drive teeth for the formula, but if I play with the numbers:
drive teeth-7 gear ratio-3.27 tire size-27
I get the 17 tooth white gear. So, by this method, can I assume that my drive teeth do equal 7 or am I way off?
Does this mean that I would need a 15 tooth gear? this is not listed on the gear website? HELP!

(I recently put on 31x10.50/15)

Thanks for the help

ozone11@cinci.rr.com

 

[Jason94sport]

You need a 16 tooth gear. It's wine colored. I did the same thing on my X.
Same gears, & tires size. The 16 tooth will correct it the closest. It will still be a little off at slower speeds.

 

[ozone]

thank you very much. I have been worrying about this. WAG is for the birds