1\12 Rollout

1/12 Rollout is a gearing calculator built for 1/12 scale pan car racers. Rollout is how far your car travels for one turn of the motor. It's the number that lets you compare gearing across different spurs and tire sizes, and it changes every time you true your tires. 1/12 Rollout works it out instantly. CALCULATE • Set your pinion, spur (64 pitch) and rear tire diameter • See rollout in millimeters or inches, plus final drive ratio • Step tire diameter in 0.1 mm as your tires wear down FIND A PINION • Enter a target rollout and get the exact pinion, the closest pinion you can actually run, and the rollout it gives you • Pinion chart shows five pinions either side of your current one with FDR and rollout. Tap a row to select it SAVE SETUPS • Save any rollout with notes, like "Snowbirds, 17.5 stock, fresh rears" • Search your saved setups and tap one to load it back into the calculator • Long press to edit notes, swipe to delete PRIVATE BY DESIGN • No account, no ads, no tracking • Your setups are stored only on your iPhone Pan cars are direct drive, so rollout = π × tire diameter × pinion ÷ spur. The app does the math so you can spend your time at the track turning laps.