Start from the paper math
Before touching the car, compute your theoretical speed in the RC Car Speed Calculator. Note the final drive ratio — that is the lever you are about to pull.
Step 1 — gearing
A larger pinion or smaller spur lowers the final drive ratio and raises theoretical speed. Make one step at a time (1–2 pinion teeth), recompute with the Gear Ratio Calculator, then run and temperature-check the motor.
Step 2 — voltage
Moving from 2S to 3S raises motor RPM proportionally — only if the ESC and motor are rated for it. Check the pack voltage with the LiPo Voltage Calculator first.
Step 3 — tires
Larger diameter tires add speed at the same wheel RPM — see the change in the Tire Size Calculator. They also add load: watch temperatures again.
Troubleshooting
Motor hot after gearing up? Gear back down a tooth — heat beats paper speed every time. Verify against the overheating guide.