Gear Ratio Chart/Pinion Gear Selection - XXX-T With 86T 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 16.075 20 10.449
14 14.927 21 9.951
15 13.932 22 9.499
16 13.061 23 9.086
17 12.293 24 8.708
18 11.610 25 8.359
19 10.999 26 8.038
Efficiency Ratio
Pinion FDR:RO - Glad II Pinion FDR:RO - Moab
13 1.204 13 1.023
14 1.118 14 0.950
15 1.043 15 0.887
16 0.978 16 0.832
17 0.921 17 0.783
18 0.870 18 0.739
19 0.824 19 0.700
20 0.783 20 0.665
21 0.745 21 0.634
22 0.711 22 0.605
23 0.681 23 0.578
24 0.652 24 0.554
25 0.626 25 0.532
26 0.602 26 0.512
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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