Speed at a given RPM — or RPM at a given speed — from gear, final drive and tyre size.
Tyre size sets rolling circumference; add your gear ratio and final drive.
Enter an engine RPM to get road speed, or a speed to get engine RPM.
Use it to check cruising RPM, top-speed limiter settings or a gear/diff swap.
Wheel RPM = engine RPM ÷ (gear ratio × final drive). Speed = wheel RPM × tyre circumference. The tool does this for you from the tyre size you enter.
The differential/crown-wheel ratio that multiplies every gear. Together with the selected gear it sets how many engine turns equal one wheel turn.
A taller tyre travels further per turn, so at the same road speed the engine spins slower — useful when fitting bigger wheels or correcting a speedo.
The desktop Softechpro Solutions software corrects checksums for 260+ ECU families and does DPF/EGR/AdBlue/DTC off, Stage tuning and DTC diagnostics offline.
See pricing — €299 one-time