Speedometer gears

[Sixtynine_Bird]

Hello guys!
Got a technical question for the plastic speedometer gear in the A833 tranny.
We've got a 3:91 rear end, and we'd like to put some 255/60/R15 back there for tires.
And with that combination I'd like to know which one of those plastics speedometer should I go with?
I've seen that for 3:91 rear end and a set of tires in 215/70/R14 (like the ones that I run with right now) combination, it is the TR-4640 orange and 40 teeth. Should I keep it or do I need a different one?

If you have any guesses do not hesitate to tell me! :encouragement:

 

[cj69RR]

Are the tires the only thing you are changing? If that is the only thing you are changing I'd leave it the way it is. You only really need to change the gear if it's a rear gear change or radical tire change.

 

[Sixtynine_Bird]

Yes this is the only thing we are changing that could affect the speedometer accuracy, we'll let the 3:91 rear end ratio and that it. We don't tuch anything else but tires.
So if you say that we should keep it we'll do that
Thanks

 

[quikbird]

I think brewer has the different gears and can tell you which one you need

 

[Big John]

Here ya go... Figure it out using their chart.

http://www.mymopar.com/speedometer.htm

 

[Sixtynine_Bird]

Ok i'll figure it out!
Thank you all!