Are you driving EP RC Car?
Are you using calculator or gearing table to find your gear ratio?
Here is good solution for gearing.

This App helps to find recently famous touring cars gearing ratio.
You select your car model, and set the spur and pinion gear size and then app finds your final gear ratio.
This app currently support following cars.

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Academy: GV2 ; SB V2 ; SB V3 ; STR-4 Pro2
Associated : RC10 T4/B4 ; B44 ; TC-5
Hotbodies : Cyclone D4 ; TC ; S
HPI: Pro-D
Kyosho : Ultima RB-5; Lazer ZX-5; TF-5
Robitronics : Avid EP
Schumacher : Mi3.5PRO; Mi4
Serpent : S400
Tamiya : TA05; TB03; TB Evo V; TRF-415(MSX);F104; F103; TRF-415(MSX MRE); TRF-416(WE/X); DB01; TRF-501X;TRF-511
Team Losi : XXX(BK/CR); XXX-G4+;JRXS Type-R
TOP : Photon
Xray : T2(R/007/008/009);T1 FK05;T3;T1(Evo2/FK/M)
Yokomo : MR4TC BD-5

We are adding other new brands and car models.
If you want to add some other car please contact to teosoft@me.com.