Gearing & speedTire size & gearing
Tire size & gearing
Compare tire diameters, then re-gear to hold the old rollout so the car keeps its speed.
Diameters & gearing
mm
mm
T
:1
Two tire sizes are enough to compare. Pinion and final drive ratio are optional, for gearing corrections. Motor RPM and growth are held fixed.
Calculated relationship
Rollout and theoretical speed change
Enter two positive tire diameters.
Kinematic comparison only: no growth, loading or real speed. Pinions need their own fitment check. Applying a change clears the GPS input.