Originally Posted by trx-1racer

Start around 90mm rollout. So gearing really depends on tire diameter.

I don't plan to run micro tires, so cut to about 43mm I'll be at 48/72 and tune by temp from there.

Longer track? Go up a tooth or 2.... Just remember, lots of factors in gearing, motor, timing, tires, track length, track surface, etc.