Torqueflite Speedometer gear choice

On a side note be sure you have the right tire dia for your calcs. GPS & some math is the best. in a parking lot getting a rear tire valve stem at 6 0'clock then rolling the car forward in a straight line till the stem is back at 6 0'clock & tape measure that distance (~8 ft) then divide Pi (3.1416) into that # for the actual dia is second best & putting something flat across the top of the tire & measureing down to the ground for diameter is 3rd (but I admit the third method did work for me) but my OCD is always on me. If it ain't dead on a whole # I would go to the next smaller tooth count (tickets ain't cheap). & something I remember from drag racers is that a tire can grow at speed.