Gear Ratio Chart/Pinion Gear Selection - XXX-T With 88T Spur
Internal Gear Ratio 2.43
  Gladiator II Tires * Moab Tires ** * Gladiator II tires w/ 4.25" diameter
Roll-out 13.352 15.708 ** Moab tires w/ 5.00" diameter
Final Drive Ratios
Pinion FDR (*:1) Pinion FDR (*:1)
13 16.449 20 10.692
14 15.274 21 10.183
15 14.256 22 9.720
16 13.365 23 9.297
17 12.579 24 8.910
18 11.880 25 8.554
19 11.255 26 8.225
Efficiency Ratio
Pinion FDR:RO - Glad II Pinion FDR:RO - Moab
13 1.232 13 1.047
14 1.144 14 0.972
15 1.068 15 0.908
16 1.001 16 0.851
17 0.942 17 0.801
18 0.890 18 0.756
19 0.843 19 0.716
20 0.801 20 0.681
21 0.763 21 0.648
22 0.728 22 0.619
23 0.696 23 0.592
24 0.667 24 0.567
25 0.641 25 0.545
26 0.616 26 0.524
1 Ideal Efficiency Ratio is closest to 1:1.  Depending on the kV of your motor, you may need to gear up or down to find the sweet spot.
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