Originally Posted by niznai
That's interesting. And what method pray tell is that?
I am afraid you have some misaprehensions about what is ideal. Ideal ratio doesn't exist outside some well defined constraints. Which means the ideal FDR for a set of conditions (grip, track, esc setup, etc) is not going to be ideal at all for another set. As you mention none of these conditions, it is nigh-on impossible for anyone to help (which is why you didn't have any answers).
Besides, there is no calculation to help you here. Run the car, take temperature readings on the motor and see if you are on pace. That's how it's done.
When I buy brushless motors,for example I was running a 10,5T, until my ESC got broken. Nosram says the final should be 6 (of course this depends on track, batteries,tires..).
Spur gear/pinion gear x internal car ratio= final ratio
Lets say I was gonna use the Brussless Nosram 10,5T:
105/40 x 2,25 = 5,90
5,90 is close to the 6 they recomend, of course that changes if I use Lipo,Life.. 5 cells, 6 cells...smaller or bigger wheels..etc
For a 25 turns brushed, there should be final ratio where start from,and this is what I don,t know.
Also I have no idea what the ideal temperature should be for brushed motors, so it makes it difficult to calculate for me.