Speedometer gear selection

[7071 challenger]

Hi guys...

I am looking for a simple formula how to calculate which speedometer gear to use for my car. I already know that my tire size is 26.10",(235/60-15), and I will use a 2.94 rear end. When I did a reseach on the net, I found that I need  a 30 teeth speedometer gear, but nobody gives the formula. The reason I am asking is, I have a 29 speedometer gear and I also have a 31 speedometer gear and I would like to know which one will be the closest for what I need.

Thanks

Robert

[brads70]

Sorry I don't have a formula, but here is all I have?

[Katfish]

Formula is

(((5280 / (C/12)) * RG ) / 1000 ) * 13

5280 = ft in mile
C = circumference of tire = tire diameter x pi = D x 3.1416
RG = Rear end gear, 2.94 for you

[7071 challenger]

Formula is

(((5280 / (C/12)) * RG ) / 1000 ) * 13

5280 = ft in mile
C = circumference of tire = tire diameter x pi = D x 3.1416
RG = Rear end gear, 2.94 for you

Katfish, excuse my lack of knowledge, but I just don't understand what the  "*"  means!!!  I know that the "/" means "divided", but the  "*"  

Robert

[Jamiez]

* is multiplication

[Chryco Psycho]

29 should be closer

[7071 challenger]

Thanks everyone

Robert