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Gear Ratio Calculator

Use our gear ratio and rollout calculator to find the right pinion and spur for your car, whether it's Team Associated, Tamiya, Traxxas, or any other make, . Enter your car's internal drive ratio to see the final drive ratio (FDR), and see the percentage change in gearing you'll get from a new pinion and spur.

Gears & Ratios

Enter your gearing to see the how your ratio will change.
Ratio
1
1
Ratio change
0%
Internal ratio
(Optional)
FDR
1
1
Rear tire diameter (Optional, for rollout)
Rollout
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Change Impact Chart

Click/tap the gears to see how new gears will affect your ratio:
Pinion
Spur
13
0%
74
0%
14
0%
75
0%
15
0%
76
0%
16
0%
77
0%
17
0%
78
0%
18
0%
79
0%
19
0%
80
0%
20
0%
81
0%
21
0%
82
0%

Negative changes indicate a steeper ratio: higher top speed, but more strain on the motor/engine. Positive changes give more acceleration and put less strain on the motor/engine.